Platform Apex Test Run

/**
 * @description Test class for {{ClassName}}
 *              Tests core functionality with positive, negative, and bulk scenarios.
 * @created     {{Date}}
 * @coverage    Target: 90%+
 */
@IsTest
private class {{ClassName}}Test {

    // ═══════════════════════════════════════════════════════════════════════════
    // TEST DATA SETUP
    // ═══════════════════════════════════════════════════════════════════════════

    @TestSetup
    static void setupTestData() {
        // Create test data using Test Data Factory pattern
        // This data is available to all test methods and rolled back after each
        List<{{ObjectName}}> records = TestDataFactory.create{{ObjectName}}s(5);
        insert records;
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // POSITIVE TESTS
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Tests successful {{methodUnderTest}} with valid input
     */
    @IsTest
    static void test{{MethodUnderTest}}_ValidInput_Success() {
        // ─────────────────────────────────────────────────────────────────────
        // GIVEN - Set up test conditions
        // ─────────────────────────────────────────────────────────────────────
        {{ObjectName}} testRecord = [SELECT Id, Name FROM {{ObjectName}} LIMIT 1];
        // TODO: Add any additional setup needed

        // ─────────────────────────────────────────────────────────────────────
        // WHEN - Execute the method under test
        // ─────────────────────────────────────────────────────────────────────
        Test.startTest();
        {{ReturnType}} result = {{ClassName}}.{{methodUnderTest}}(testRecord);
        Test.stopTest();

        // ─────────────────────────────────────────────────────────────────────
        // THEN - Verify expected outcomes
        // ─────────────────────────────────────────────────────────────────────
        Assert.isNotNull(result, 'Result should not be null');
        // TODO: Add specific assertions for expected values
        // Assert.areEqual(expectedValue, result, 'Result should match expected value');
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // NEGATIVE TESTS
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Tests {{methodUnderTest}} throws exception with null input
     */
    @IsTest
    static void test{{MethodUnderTest}}_NullInput_ThrowsException() {
        // ─────────────────────────────────────────────────────────────────────
        // GIVEN - Null input
        // ─────────────────────────────────────────────────────────────────────
        {{ObjectName}} nullRecord = null;

        // ─────────────────────────────────────────────────────────────────────
        // WHEN/THEN - Verify exception is thrown
        // ─────────────────────────────────────────────────────────────────────
        try {
            Test.startTest();
            {{ClassName}}.{{methodUnderTest}}(nullRecord);
            Test.stopTest();
            Assert.fail('Expected exception was not thrown');
        } catch (IllegalArgumentException e) {
            Assert.isTrue(
                e.getMessage().containsIgnoreCase('null') ||
                e.getMessage().containsIgnoreCase('required'),
                'Error message should indicate null/required issue: ' + e.getMessage()
            );
        }
    }

    /**
     * @description Tests {{methodUnderTest}} handles invalid data gracefully
     */
    @IsTest
    static void test{{MethodUnderTest}}_InvalidData_ReturnsError() {
        // ─────────────────────────────────────────────────────────────────────
        // GIVEN - Invalid input data
        // ─────────────────────────────────────────────────────────────────────
        {{ObjectName}} invalidRecord = new {{ObjectName}}(
            // TODO: Set invalid field values that should fail validation
        );

        // ─────────────────────────────────────────────────────────────────────
        // WHEN - Execute with invalid data
        // ─────────────────────────────────────────────────────────────────────
        Test.startTest();
        // TODO: Call method and capture result/exception
        Test.stopTest();

        // ─────────────────────────────────────────────────────────────────────
        // THEN - Verify appropriate error handling
        // ─────────────────────────────────────────────────────────────────────
        // TODO: Assert error message or state
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // BULK TESTS (251+ records)
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Tests {{methodUnderTest}} handles bulk operations (251 records)
     *              251 records crosses the 200-record trigger batch boundary
     */
    @IsTest
    static void test{{MethodUnderTest}}_BulkOperation_Success() {
        // ─────────────────────────────────────────────────────────────────────
        // GIVEN - 251 records (crosses 200-record batch boundary)
        // ─────────────────────────────────────────────────────────────────────
        List<{{ObjectName}}> bulkRecords = TestDataFactory.create{{ObjectName}}s(251);

        // ─────────────────────────────────────────────────────────────────────
        // WHEN - Process bulk records
        // ─────────────────────────────────────────────────────────────────────
        Test.startTest();
        insert bulkRecords;  // Triggers fire in batches of 200, then 51
        Test.stopTest();

        // ─────────────────────────────────────────────────────────────────────
        // THEN - Verify all records processed without governor limit issues
        // ─────────────────────────────────────────────────────────────────────
        Integer recordCount = [SELECT COUNT() FROM {{ObjectName}}];
        Assert.isTrue(recordCount >= 251, 'All 251 records should be processed');

        // Verify governor limits not approached
        Assert.isTrue(Limits.getQueries() < 90,
            'SOQL queries should stay well under limit: ' + Limits.getQueries() + '/100');
        Assert.isTrue(Limits.getDmlStatements() < 140,
            'DML statements should stay under limit: ' + Limits.getDmlStatements() + '/150');
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // EDGE CASE TESTS
    // ═══════════════════════════════════════════════────────────────────────────

    /**
     * @description Tests {{methodUnderTest}} with empty list input
     */
    @IsTest
    static void test{{MethodUnderTest}}_EmptyList_NoError() {
        // ─────────────────────────────────────────────────────────────────────
        // GIVEN - Empty list
        // ─────────────────────────────────────────────────────────────────────
        List<{{ObjectName}}> emptyList = new List<{{ObjectName}}>();

        // ─────────────────────────────────────────────────────────────────────
        // WHEN - Process empty list
        // ─────────────────────────────────────────────────────────────────────
        Test.startTest();
        // TODO: Call method with empty list
        Test.stopTest();

        // ─────────────────────────────────────────────────────────────────────
        // THEN - Should handle gracefully (no exception)
        // ─────────────────────────────────────────────────────────────────────
        // TODO: Assert appropriate handling
    }
}

/**
 * @description Bulk testing template for trigger and service validation
 *              Tests with 251+ records to ensure bulkification compliance.
 *              251 records crosses the 200-record trigger batch boundary.
 * @created     {{Date}}
 */
@IsTest
private class {{ClassName}}BulkTest {

    // Record counts for different test scenarios
    private static final Integer BULK_SIZE = 251;       // Crosses 200-batch boundary
    private static final Integer LARGE_BULK_SIZE = 501; // Multiple batch boundaries
    private static final Integer SINGLE_BATCH = 200;    // Single batch (edge case)

    // ═══════════════════════════════════════════════════════════════════════════
    // BULK INSERT TESTS
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Tests bulk insert with 251 records
     *              Verifies trigger handles multiple batch chunks correctly
     */
    @IsTest
    static void testBulkInsert_251Records_AllProcessed() {
        // GIVEN
        List<{{ObjectName}}> records = TestDataFactory.create{{ObjectName}}s(BULK_SIZE);

        // WHEN
        Test.startTest();
        Database.SaveResult[] results = Database.insert(records, false);
        Test.stopTest();

        // THEN - All records should be successfully inserted
        Integer successCount = 0;
        Integer failCount = 0;
        for (Database.SaveResult sr : results) {
            if (sr.isSuccess()) {
                successCount++;
            } else {
                failCount++;
                System.debug('Insert failed: ' + sr.getErrors()[0].getMessage());
            }
        }

        Assert.areEqual(BULK_SIZE, successCount,
            'All ' + BULK_SIZE + ' records should insert successfully');
        Assert.areEqual(0, failCount, 'No records should fail');

        // Verify governor limits
        assertGovernorLimitsNotExceeded();
    }

    /**
     * @description Tests bulk insert at exact batch boundary (200 records)
     */
    @IsTest
    static void testBulkInsert_ExactBatchSize_AllProcessed() {
        // GIVEN
        List<{{ObjectName}}> records = TestDataFactory.create{{ObjectName}}s(SINGLE_BATCH);

        // WHEN
        Test.startTest();
        insert records;
        Test.stopTest();

        // THEN
        Integer count = [SELECT COUNT() FROM {{ObjectName}}];
        Assert.areEqual(SINGLE_BATCH, count,
            'All ' + SINGLE_BATCH + ' records should be inserted');
        assertGovernorLimitsNotExceeded();
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // BULK UPDATE TESTS
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Tests bulk update with 251 records
     *              Verifies update triggers handle multiple batches
     */
    @IsTest
    static void testBulkUpdate_251Records_AllUpdated() {
        // GIVEN - Insert records first
        List<{{ObjectName}}> records = TestDataFactory.create{{ObjectName}}s(BULK_SIZE);
        insert records;

        // Modify all records
        for ({{ObjectName}} rec : records) {
            // TODO: Update fields that trigger logic
            // rec.SomeField__c = 'Updated Value';
        }

        // WHEN
        Test.startTest();
        Database.SaveResult[] results = Database.update(records, false);
        Test.stopTest();

        // THEN
        Integer successCount = 0;
        for (Database.SaveResult sr : results) {
            if (sr.isSuccess()) {
                successCount++;
            }
        }

        Assert.areEqual(BULK_SIZE, successCount,
            'All ' + BULK_SIZE + ' records should update successfully');
        assertGovernorLimitsNotExceeded();
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // BULK DELETE TESTS
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Tests bulk delete with 251 records
     *              Verifies delete triggers handle cleanup correctly
     */
    @IsTest
    static void testBulkDelete_251Records_AllDeleted() {
        // GIVEN
        List<{{ObjectName}}> records = TestDataFactory.create{{ObjectName}}s(BULK_SIZE);
        insert records;

        // WHEN
        Test.startTest();
        Database.DeleteResult[] results = Database.delete(records, false);
        Test.stopTest();

        // THEN
        Integer successCount = 0;
        for (Database.DeleteResult dr : results) {
            if (dr.isSuccess()) {
                successCount++;
            }
        }

        Assert.areEqual(BULK_SIZE, successCount,
            'All ' + BULK_SIZE + ' records should delete successfully');

        Integer remainingCount = [SELECT COUNT() FROM {{ObjectName}}];
        Assert.areEqual(0, remainingCount, 'No records should remain');
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // MIXED DML BULK TESTS
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Tests mixed operations in bulk
     *              Verifies partial success scenarios are handled
     */
    @IsTest
    static void testBulkMixedOperations_PartialSuccess() {
        // GIVEN - Some valid, some invalid records
        List<{{ObjectName}}> validRecords = TestDataFactory.create{{ObjectName}}s(200);
        List<{{ObjectName}}> invalidRecords = new List<{{ObjectName}}>();

        // Create invalid records (missing required fields or validation failures)
        for (Integer i = 0; i < 51; i++) {
            invalidRecords.add(new {{ObjectName}}(
                // TODO: Set up record that will fail validation
            ));
        }

        List<{{ObjectName}}> allRecords = new List<{{ObjectName}}>();
        allRecords.addAll(validRecords);
        allRecords.addAll(invalidRecords);

        // WHEN - Insert with allOrNone = false
        Test.startTest();
        Database.SaveResult[] results = Database.insert(allRecords, false);
        Test.stopTest();

        // THEN - Count successes and failures
        Integer successCount = 0;
        Integer failCount = 0;
        for (Database.SaveResult sr : results) {
            if (sr.isSuccess()) {
                successCount++;
            } else {
                failCount++;
            }
        }

        // Verify partial success handled correctly
        Assert.isTrue(successCount > 0, 'Some records should succeed');
        // Note: Uncomment if you expect failures
        // Assert.isTrue(failCount > 0, 'Some records should fail validation');
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // GOVERNOR LIMIT VERIFICATION
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Helper method to verify governor limits not exceeded
     *              Call after Test.stopTest() to check limit usage
     */
    private static void assertGovernorLimitsNotExceeded() {
        // SOQL Queries (limit: 100)
        Assert.isTrue(Limits.getQueries() < 90,
            'SOQL queries approaching limit: ' + Limits.getQueries() + '/100');

        // DML Statements (limit: 150)
        Assert.isTrue(Limits.getDmlStatements() < 140,
            'DML statements approaching limit: ' + Limits.getDmlStatements() + '/150');

        // DML Rows (limit: 10,000)
        Assert.isTrue(Limits.getDmlRows() < 9500,
            'DML rows approaching limit: ' + Limits.getDmlRows() + '/10000');

        // Heap Size (limit: 6MB sync, 12MB async)
        Assert.isTrue(Limits.getHeapSize() < 5000000,
            'Heap size approaching limit: ' + Limits.getHeapSize() + '/6000000');

        // CPU Time (limit: 10,000ms sync, 60,000ms async)
        Assert.isTrue(Limits.getCpuTime() < 9000,
            'CPU time approaching limit: ' + Limits.getCpuTime() + '/10000');

        System.debug('═══════════════════════════════════════════════════════');
        System.debug('GOVERNOR LIMIT USAGE:');
        System.debug('  SOQL Queries: ' + Limits.getQueries() + '/100');
        System.debug('  DML Statements: ' + Limits.getDmlStatements() + '/150');
        System.debug('  DML Rows: ' + Limits.getDmlRows() + '/10000');
        System.debug('  Heap Size: ' + Limits.getHeapSize() + '/6000000');
        System.debug('  CPU Time: ' + Limits.getCpuTime() + 'ms /10000ms');
        System.debug('═══════════════════════════════════════════════════════');
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // STRESS TESTS (Optional - Run sparingly)
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Stress test with 501 records (multiple batch boundaries)
     *              Use sparingly - consumes significant test execution time
     */
    @IsTest
    static void testStressTest_501Records_AllProcessed() {
        // GIVEN
        List<{{ObjectName}}> records = TestDataFactory.create{{ObjectName}}s(LARGE_BULK_SIZE);

        // WHEN
        Test.startTest();
        insert records;
        Test.stopTest();

        // THEN
        Integer count = [SELECT COUNT() FROM {{ObjectName}}];
        Assert.areEqual(LARGE_BULK_SIZE, count,
            'All ' + LARGE_BULK_SIZE + ' records should be processed');
        assertGovernorLimitsNotExceeded();
    }
}

/**
 * DML Mocking Framework
 *
 * Enables true unit testing by replacing database operations with in-memory tracking.
 * Tests using this pattern run ~35x faster than tests with actual DML.
 *
 * See: references/mocking-patterns.md for usage guidance
 */

// ═══════════════════════════════════════════════════════════════════════════
// INTERFACE: IDML
// Define the contract for DML operations
// ═══════════════════════════════════════════════════════════════════════════

/**
 * Interface for DML operations - enables dependency injection
 */
public interface IDML {
    void doInsert(SObject record);
    void doInsert(List<SObject> records);
    void doUpdate(SObject record);
    void doUpdate(List<SObject> records);
    void doUpsert(SObject record);
    void doUpsert(List<SObject> records);
    void doDelete(SObject record);
    void doDelete(List<SObject> records);
}

// ═══════════════════════════════════════════════════════════════════════════
// PRODUCTION: DML
// Performs actual database operations
// ═══════════════════════════════════════════════════════════════════════════

/**
 * Production implementation performing real database operations
 */
public class DML implements IDML {

    public void doInsert(SObject record) {
        insert record;
    }

    public void doInsert(List<SObject> records) {
        if (records != null && !records.isEmpty()) {
            insert records;
        }
    }

    public void doUpdate(SObject record) {
        update record;
    }

    public void doUpdate(List<SObject> records) {
        if (records != null && !records.isEmpty()) {
            update records;
        }
    }

    public void doUpsert(SObject record) {
        upsert record;
    }

    public void doUpsert(List<SObject> records) {
        if (records != null && !records.isEmpty()) {
            upsert records;
        }
    }

    public void doDelete(SObject record) {
        delete record;
    }

    public void doDelete(List<SObject> records) {
        if (records != null && !records.isEmpty()) {
            delete records;
        }
    }
}

// ═══════════════════════════════════════════════════════════════════════════
// TEST MOCK: DMLMock
// Tracks operations without hitting the database
// ═══════════════════════════════════════════════════════════════════════════

/**
 * Mock DML implementation for fast unit tests
 *
 * Usage:
 *   DMLMock.reset();
 *   MyService service = new MyService(new DMLMock());
 *   service.doSomething();
 *   Assert.areEqual(1, DMLMock.InsertedRecords.size());
 */
@IsTest
public class DMLMock implements IDML {

    // ═══════════════════════════════════════════════════════════════════
    // TRACKED OPERATIONS
    // ═══════════════════════════════════════════════════════════════════

    public static List<SObject> InsertedRecords = new List<SObject>();
    public static List<SObject> UpdatedRecords = new List<SObject>();
    public static List<SObject> UpsertedRecords = new List<SObject>();
    public static List<SObject> DeletedRecords = new List<SObject>();

    // Counter for generating unique fake IDs
    private static Integer idCounter = 1;

    // ═══════════════════════════════════════════════════════════════════
    // DML OPERATIONS
    // ═══════════════════════════════════════════════════════════════════

    public void doInsert(SObject record) {
        doInsert(new List<SObject>{ record });
    }

    public void doInsert(List<SObject> records) {
        if (records == null || records.isEmpty()) {
            return;
        }
        for (SObject record : records) {
            // Generate fake ID to simulate database insert
            if (record.Id == null) {
                record.Id = generateFakeId(record.getSObjectType());
            }
            InsertedRecords.add(record);
        }
    }

    public void doUpdate(SObject record) {
        doUpdate(new List<SObject>{ record });
    }

    public void doUpdate(List<SObject> records) {
        if (records != null && !records.isEmpty()) {
            UpdatedRecords.addAll(records);
        }
    }

    public void doUpsert(SObject record) {
        doUpsert(new List<SObject>{ record });
    }

    public void doUpsert(List<SObject> records) {
        if (records != null && !records.isEmpty()) {
            for (SObject record : records) {
                if (record.Id == null) {
                    record.Id = generateFakeId(record.getSObjectType());
                }
            }
            UpsertedRecords.addAll(records);
        }
    }

    public void doDelete(SObject record) {
        doDelete(new List<SObject>{ record });
    }

    public void doDelete(List<SObject> records) {
        if (records != null && !records.isEmpty()) {
            DeletedRecords.addAll(records);
        }
    }

    // ═══════════════════════════════════════════════════════════════════
    // UTILITY METHODS
    // ═══════════════════════════════════════════════════════════════════

    /**
     * Reset all tracked operations - call at start of each test
     */
    public static void reset() {
        InsertedRecords.clear();
        UpdatedRecords.clear();
        UpsertedRecords.clear();
        DeletedRecords.clear();
        idCounter = 1;
    }

    /**
     * Generate a valid Salesforce ID for testing
     * Uses the object's key prefix for realistic IDs
     */
    private static Id generateFakeId(Schema.SObjectType sObjectType) {
        String keyPrefix = sObjectType.getDescribe().getKeyPrefix();
        if (keyPrefix == null) {
            keyPrefix = '000';  // Fallback for objects without prefix
        }
        String idBody = String.valueOf(idCounter++).leftPad(12, '0');
        return Id.valueOf(keyPrefix + idBody);
    }

    // ═══════════════════════════════════════════════════════════════════
    // HELPER METHODS FOR ASSERTIONS
    // ═══════════════════════════════════════════════════════════════════

    /**
     * Get inserted records of a specific SObject type
     */
    public static List<SObject> getInsertedOfType(Schema.SObjectType sObjectType) {
        List<SObject> result = new List<SObject>();
        for (SObject record : InsertedRecords) {
            if (record.getSObjectType() == sObjectType) {
                result.add(record);
            }
        }
        return result;
    }

    /**
     * Get updated records of a specific SObject type
     */
    public static List<SObject> getUpdatedOfType(Schema.SObjectType sObjectType) {
        List<SObject> result = new List<SObject>();
        for (SObject record : UpdatedRecords) {
            if (record.getSObjectType() == sObjectType) {
                result.add(record);
            }
        }
        return result;
    }

    /**
     * Get deleted records of a specific SObject type
     */
    public static List<SObject> getDeletedOfType(Schema.SObjectType sObjectType) {
        List<SObject> result = new List<SObject>();
        for (SObject record : DeletedRecords) {
            if (record.getSObjectType() == sObjectType) {
                result.add(record);
            }
        }
        return result;
    }

    /**
     * Check if any records of a specific type were inserted
     */
    public static Boolean wasInserted(Schema.SObjectType sObjectType) {
        return !getInsertedOfType(sObjectType).isEmpty();
    }

    /**
     * Check if any records of a specific type were updated
     */
    public static Boolean wasUpdated(Schema.SObjectType sObjectType) {
        return !getUpdatedOfType(sObjectType).isEmpty();
    }

    /**
     * Check if any records of a specific type were deleted
     */
    public static Boolean wasDeleted(Schema.SObjectType sObjectType) {
        return !getDeletedOfType(sObjectType).isEmpty();
    }
}

// ═══════════════════════════════════════════════════════════════════════════
// EXAMPLE: Service Using Injected DML
// ═══════════════════════════════════════════════════════════════════════════

/**
 * Example service class demonstrating DML injection
 */
public class AccountService {

    private IDML dml;

    // Production constructor - uses real DML
    public AccountService() {
        this(new DML());
    }

    // Test constructor - accepts mock DML
    @TestVisible
    private AccountService(IDML dml) {
        this.dml = dml;
    }

    public Id createAccount(Account acc) {
        if (acc == null) {
            throw new IllegalArgumentException('Account cannot be null');
        }
        dml.doInsert(acc);
        return acc.Id;
    }

    public void updateAccounts(List<Account> accounts) {
        dml.doUpdate(accounts);
    }
}

// ═══════════════════════════════════════════════════════════════════════════
// EXAMPLE: Test Class Using DML Mock
// ═══════════════════════════════════════════════════════════════════════════

@IsTest
private class AccountServiceTest {

    @IsTest
    static void testCreateAccount_Success() {
        // Arrange
        DMLMock.reset();
        AccountService service = new AccountService(new DMLMock());
        Account testAcc = new Account(Name = 'Test Corp', Industry = 'Technology');

        // Act
        Test.startTest();
        Id accountId = service.createAccount(testAcc);
        Test.stopTest();

        // Assert
        Assert.isNotNull(accountId, 'Should have generated ID');
        Assert.areEqual(1, DMLMock.InsertedRecords.size(), 'Should have 1 insert');
        Assert.isTrue(DMLMock.wasInserted(Account.SObjectType), 'Account was inserted');

        Account inserted = (Account) DMLMock.InsertedRecords[0];
        Assert.areEqual('Test Corp', inserted.Name, 'Name should match');
        Assert.areEqual('Technology', inserted.Industry, 'Industry should match');
    }

    @IsTest
    static void testCreateAccount_NullInput_ThrowsException() {
        // Arrange
        DMLMock.reset();
        AccountService service = new AccountService(new DMLMock());

        // Act/Assert
        try {
            service.createAccount(null);
            Assert.fail('Expected IllegalArgumentException');
        } catch (IllegalArgumentException e) {
            Assert.isTrue(e.getMessage().contains('null'), 'Error should mention null');
        }

        // Verify no DML occurred
        Assert.areEqual(0, DMLMock.InsertedRecords.size(), 'No records should be inserted');
    }
}

/**
 * @description Test class for external API callouts using mock framework
 *              Demonstrates HttpCalloutMock and WebServiceMock patterns.
 * @created     {{Date}}
 */
@IsTest
private class {{ClassName}}CalloutTest {

    // ═══════════════════════════════════════════════════════════════════════════
    // MOCK IMPLEMENTATIONS
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Mock for successful HTTP response (200 OK)
     */
    private class SuccessMock implements HttpCalloutMock {
        public HttpResponse respond(HttpRequest req) {
            HttpResponse res = new HttpResponse();
            res.setStatusCode(200);
            res.setStatus('OK');
            res.setHeader('Content-Type', 'application/json');
            res.setBody(JSON.serialize(new Map<String, Object>{
                'success' => true,
                'data' => new Map<String, Object>{
                    'id' => '12345',
                    'status' => 'completed',
                    'timestamp' => Datetime.now().format()
                }
            }));
            return res;
        }
    }

    /**
     * @description Mock for error HTTP response (500 Internal Server Error)
     */
    private class ErrorMock implements HttpCalloutMock {
        private Integer statusCode;
        private String errorMessage;

        public ErrorMock(Integer statusCode, String errorMessage) {
            this.statusCode = statusCode;
            this.errorMessage = errorMessage;
        }

        public HttpResponse respond(HttpRequest req) {
            HttpResponse res = new HttpResponse();
            res.setStatusCode(this.statusCode);
            res.setStatus('Error');
            res.setHeader('Content-Type', 'application/json');
            res.setBody(JSON.serialize(new Map<String, Object>{
                'success' => false,
                'error' => this.errorMessage
            }));
            return res;
        }
    }

    /**
     * @description Mock for timeout simulation
     */
    private class TimeoutMock implements HttpCalloutMock {
        public HttpResponse respond(HttpRequest req) {
            // Simulate timeout by throwing CalloutException
            throw new CalloutException('Read timed out');
        }
    }

    /**
     * @description Mock that validates request parameters
     */
    private class ValidatingMock implements HttpCalloutMock {
        private String expectedEndpoint;
        private String expectedMethod;

        public ValidatingMock(String endpoint, String method) {
            this.expectedEndpoint = endpoint;
            this.expectedMethod = method;
        }

        public HttpResponse respond(HttpRequest req) {
            // Validate the request
            System.assertEquals(expectedMethod, req.getMethod(),
                'HTTP method should be ' + expectedMethod);
            System.assert(req.getEndpoint().contains(expectedEndpoint),
                'Endpoint should contain ' + expectedEndpoint);

            HttpResponse res = new HttpResponse();
            res.setStatusCode(200);
            res.setBody('{"validated": true}');
            return res;
        }
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // SUCCESS TESTS
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Tests successful API call returns expected data
     */
    @IsTest
    static void testCallout_Success_ReturnsData() {
        // GIVEN
        Test.setMock(HttpCalloutMock.class, new SuccessMock());

        // WHEN
        Test.startTest();
        // TODO: Replace with your actual service call
        // {{ClassName}}Response response = {{ClassName}}.callExternalAPI('test-param');
        HttpRequest req = new HttpRequest();
        req.setEndpoint('https://api.example.com/test');
        req.setMethod('GET');
        HttpResponse res = new Http().send(req);
        Test.stopTest();

        // THEN
        Assert.areEqual(200, res.getStatusCode(), 'Should return 200 OK');

        Map<String, Object> responseBody = (Map<String, Object>) JSON.deserializeUntyped(res.getBody());
        Assert.areEqual(true, responseBody.get('success'), 'Response should indicate success');
        Assert.isNotNull(responseBody.get('data'), 'Response should contain data');
    }

    /**
     * @description Tests POST request with body
     */
    @IsTest
    static void testCallout_PostWithBody_Success() {
        // GIVEN
        Test.setMock(HttpCalloutMock.class, new SuccessMock());

        Map<String, Object> requestBody = new Map<String, Object>{
            'name' => 'Test Record',
            'value' => 100
        };

        // WHEN
        Test.startTest();
        HttpRequest req = new HttpRequest();
        req.setEndpoint('https://api.example.com/create');
        req.setMethod('POST');
        req.setHeader('Content-Type', 'application/json');
        req.setBody(JSON.serialize(requestBody));
        HttpResponse res = new Http().send(req);
        Test.stopTest();

        // THEN
        Assert.areEqual(200, res.getStatusCode(), 'POST should succeed');
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // ERROR HANDLING TESTS
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Tests handling of 400 Bad Request
     */
    @IsTest
    static void testCallout_BadRequest_HandlesGracefully() {
        // GIVEN
        Test.setMock(HttpCalloutMock.class, new ErrorMock(400, 'Invalid request parameters'));

        // WHEN
        Test.startTest();
        HttpRequest req = new HttpRequest();
        req.setEndpoint('https://api.example.com/test');
        req.setMethod('GET');
        HttpResponse res = new Http().send(req);
        Test.stopTest();

        // THEN
        Assert.areEqual(400, res.getStatusCode(), 'Should return 400');

        Map<String, Object> errorBody = (Map<String, Object>) JSON.deserializeUntyped(res.getBody());
        Assert.areEqual(false, errorBody.get('success'), 'Should indicate failure');
        Assert.isNotNull(errorBody.get('error'), 'Should contain error message');
    }

    /**
     * @description Tests handling of 500 Internal Server Error
     */
    @IsTest
    static void testCallout_ServerError_HandlesGracefully() {
        // GIVEN
        Test.setMock(HttpCalloutMock.class, new ErrorMock(500, 'Internal server error'));

        // WHEN
        Test.startTest();
        HttpRequest req = new HttpRequest();
        req.setEndpoint('https://api.example.com/test');
        req.setMethod('GET');
        HttpResponse res = new Http().send(req);
        Test.stopTest();

        // THEN
        Assert.areEqual(500, res.getStatusCode(), 'Should return 500');
    }

    /**
     * @description Tests handling of timeout exception
     */
    @IsTest
    static void testCallout_Timeout_ThrowsException() {
        // GIVEN
        Test.setMock(HttpCalloutMock.class, new TimeoutMock());

        // WHEN/THEN
        Test.startTest();
        try {
            HttpRequest req = new HttpRequest();
            req.setEndpoint('https://api.example.com/slow');
            req.setMethod('GET');
            new Http().send(req);
            Assert.fail('Expected CalloutException was not thrown');
        } catch (CalloutException e) {
            Assert.isTrue(e.getMessage().containsIgnoreCase('timeout'),
                'Exception should mention timeout: ' + e.getMessage());
        }
        Test.stopTest();
    }

    /**
     * @description Tests handling of 401 Unauthorized
     */
    @IsTest
    static void testCallout_Unauthorized_HandlesGracefully() {
        // GIVEN
        Test.setMock(HttpCalloutMock.class, new ErrorMock(401, 'Invalid or expired token'));

        // WHEN
        Test.startTest();
        HttpRequest req = new HttpRequest();
        req.setEndpoint('https://api.example.com/protected');
        req.setMethod('GET');
        HttpResponse res = new Http().send(req);
        Test.stopTest();

        // THEN
        Assert.areEqual(401, res.getStatusCode(), 'Should return 401 Unauthorized');
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // REQUEST VALIDATION TESTS
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Verifies correct endpoint and method are used
     */
    @IsTest
    static void testCallout_ValidatesRequestParameters() {
        // GIVEN
        Test.setMock(HttpCalloutMock.class, new ValidatingMock('/api/v1/resource', 'POST'));

        // WHEN
        Test.startTest();
        HttpRequest req = new HttpRequest();
        req.setEndpoint('https://api.example.com/api/v1/resource');
        req.setMethod('POST');
        req.setBody('{"test": true}');
        HttpResponse res = new Http().send(req);
        Test.stopTest();

        // THEN - Mock validates; test passes if no assertion failure
        Assert.areEqual(200, res.getStatusCode(), 'Request should be valid');
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // ASYNC CALLOUT TESTS (@future, Queueable)
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Tests @future method with callout
     *              Note: Must use Test.startTest/stopTest to execute @future
     */
    @IsTest
    static void testFutureCallout_ExecutesSuccessfully() {
        // GIVEN
        Test.setMock(HttpCalloutMock.class, new SuccessMock());

        // WHEN - Call @future method
        Test.startTest();
        // TODO: Replace with your actual @future method
        // {{ClassName}}.makeAsyncCallout('test-param');
        Test.stopTest();  // Forces @future to execute

        // THEN - Verify results (may need to query for side effects)
        // TODO: Add assertions based on what @future method does
    }

    /**
     * @description Tests Queueable with callout
     */
    @IsTest
    static void testQueueableCallout_ExecutesSuccessfully() {
        // GIVEN
        Test.setMock(HttpCalloutMock.class, new SuccessMock());

        // WHEN
        Test.startTest();
        // TODO: Replace with your actual Queueable
        // System.enqueueJob(new {{ClassName}}Queueable('param'));
        Test.stopTest();  // Forces Queueable to execute

        // THEN - Verify results
        // TODO: Add assertions
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // MULTI-CALLOUT TESTS
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Mock for multiple sequential callouts
     */
    private class MultiCalloutMock implements HttpCalloutMock {
        private Integer callCount = 0;

        public HttpResponse respond(HttpRequest req) {
            callCount++;
            HttpResponse res = new HttpResponse();
            res.setStatusCode(200);
            res.setBody('{"callNumber": ' + callCount + '}');
            return res;
        }
    }

    /**
     * @description Tests multiple callouts in sequence (limit: 100 per transaction)
     */
    @IsTest
    static void testMultipleCallouts_AllSucceed() {
        // GIVEN
        Test.setMock(HttpCalloutMock.class, new MultiCalloutMock());

        // WHEN - Make multiple callouts
        Test.startTest();
        List<HttpResponse> responses = new List<HttpResponse>();
        for (Integer i = 0; i < 5; i++) {
            HttpRequest req = new HttpRequest();
            req.setEndpoint('https://api.example.com/call/' + i);
            req.setMethod('GET');
            responses.add(new Http().send(req));
        }
        Test.stopTest();

        // THEN
        Assert.areEqual(5, responses.size(), 'Should complete 5 callouts');
        for (HttpResponse res : responses) {
            Assert.areEqual(200, res.getStatusCode(), 'Each callout should succeed');
        }
    }
}

/**
 * StubProvider Examples
 *
 * The Stub API enables dynamic mocking of interfaces and virtual classes.
 * Use when you need conditional logic or method tracking in your mocks.
 *
 * See: references/mocking-patterns.md for detailed patterns and usage guidance
 */

// ═══════════════════════════════════════════════════════════════════════════
// EXAMPLE 1: Simple StubProvider for Interface
// ═══════════════════════════════════════════════════════════════════════════

/**
 * Interface to be stubbed
 */
public interface IAccountService {
    Account getAccount(Id accountId);
    List<Account> getAccounts(Set<Id> accountIds);
    Integer getAccountCount();
    void updateAccount(Account acc);
}

/**
 * Basic stub implementation with configurable responses
 */
@IsTest
public class AccountServiceStub implements System.StubProvider {

    // Track method calls for verification
    public List<String> calledMethods = new List<String>();
    public Map<String, List<Object>> methodParams = new Map<String, List<Object>>();

    // Configurable responses
    private Map<String, Object> responses = new Map<String, Object>();

    /**
     * Configure what a method should return
     */
    public AccountServiceStub whenCalled(String methodName, Object response) {
        responses.put(methodName, response);
        return this;
    }

    /**
     * Required StubProvider method
     */
    public Object handleMethodCall(
        Object stubbedObject,
        String stubbedMethodName,
        Type returnType,
        List<Type> paramTypes,
        List<String> paramNames,
        List<Object> paramValues
    ) {
        // Track this call
        calledMethods.add(stubbedMethodName);
        methodParams.put(stubbedMethodName, paramValues);

        // Return configured response if available
        if (responses.containsKey(stubbedMethodName)) {
            return responses.get(stubbedMethodName);
        }

        // Default responses based on return type
        if (returnType == Account.class) {
            return new Account(Id = generateFakeId(), Name = 'Default Stub Account');
        }
        if (returnType == List<Account>.class) {
            return new List<Account>{
                new Account(Id = generateFakeId(), Name = 'Stub Account 1')
            };
        }
        if (returnType == Integer.class) {
            return 0;
        }

        return null;
    }

    /**
     * Verify a method was called
     */
    public Boolean wasCalled(String methodName) {
        return calledMethods.contains(methodName);
    }

    /**
     * Get call count for a method
     */
    public Integer getCallCount(String methodName) {
        Integer count = 0;
        for (String called : calledMethods) {
            if (called == methodName) {
                count++;
            }
        }
        return count;
    }

    // Fake ID generator
    private static Integer idCounter = 1;
    private static Id generateFakeId() {
        String idBody = String.valueOf(idCounter++).leftPad(12, '0');
        return Id.valueOf('001' + idBody);
    }
}

// ═══════════════════════════════════════════════════════════════════════════
// EXAMPLE 2: Using the Stub in Tests
// ═══════════════════════════════════════════════════════════════════════════

@IsTest
private class AccountServiceStubTest {

    @IsTest
    static void testWithConfiguredResponse() {
        // Arrange - Configure stub responses
        AccountServiceStub stub = new AccountServiceStub()
            .whenCalled('getAccountCount', 42)
            .whenCalled('getAccount', new Account(Name = 'Configured Account'));

        // Create stubbed instance
        IAccountService service = (IAccountService) Test.createStub(
            IAccountService.class,
            stub
        );

        // Act
        Test.startTest();
        Integer count = service.getAccountCount();
        Account acc = service.getAccount(null);
        Test.stopTest();

        // Assert - Verify responses
        Assert.areEqual(42, count, 'Should return configured count');
        Assert.areEqual('Configured Account', acc.Name, 'Should return configured account');

        // Assert - Verify calls were tracked
        Assert.isTrue(stub.wasCalled('getAccountCount'), 'getAccountCount was called');
        Assert.isTrue(stub.wasCalled('getAccount'), 'getAccount was called');
        Assert.areEqual(1, stub.getCallCount('getAccountCount'), 'Called once');
    }

    @IsTest
    static void testDefaultResponses() {
        // Arrange - No configured responses
        AccountServiceStub stub = new AccountServiceStub();
        IAccountService service = (IAccountService) Test.createStub(
            IAccountService.class,
            stub
        );

        // Act
        Test.startTest();
        Account acc = service.getAccount(null);
        Test.stopTest();

        // Assert - Verify default response
        Assert.isNotNull(acc, 'Should return default account');
        Assert.areEqual('Default Stub Account', acc.Name, 'Should have default name');
    }
}

// ═══════════════════════════════════════════════════════════════════════════
// EXAMPLE 3: Conditional StubProvider
// ═══════════════════════════════════════════════════════════════════════════

/**
 * Stub with conditional logic based on parameters
 */
@IsTest
public class ConditionalStub implements System.StubProvider {

    public Object handleMethodCall(
        Object stubbedObject,
        String stubbedMethodName,
        Type returnType,
        List<Type> paramTypes,
        List<String> paramNames,
        List<Object> paramValues
    ) {
        // Conditional response based on method and params
        if (stubbedMethodName == 'getAccount') {
            Id requestedId = (Id) paramValues[0];

            // Return different accounts based on ID pattern
            String idStr = String.valueOf(requestedId);
            if (idStr.startsWith('001')) {
                return new Account(Id = requestedId, Name = 'Standard Account');
            } else if (idStr.startsWith('0018')) {
                return new Account(Id = requestedId, Name = 'Person Account');
            }
        }

        if (stubbedMethodName == 'getAccountCount') {
            // Simulate different counts for different scenarios
            return 100;
        }

        return null;
    }
}

// ═══════════════════════════════════════════════════════════════════════════
// EXAMPLE 4: Exception-Throwing Stub
// ═══════════════════════════════════════════════════════════════════════════

/**
 * Stub that throws exceptions for error testing
 */
@IsTest
public class ErrorStub implements System.StubProvider {

    private String methodToFail;
    private String errorMessage;

    public ErrorStub failOn(String methodName, String message) {
        this.methodToFail = methodName;
        this.errorMessage = message;
        return this;
    }

    public Object handleMethodCall(
        Object stubbedObject,
        String stubbedMethodName,
        Type returnType,
        List<Type> paramTypes,
        List<String> paramNames,
        List<Object> paramValues
    ) {
        if (stubbedMethodName == methodToFail) {
            throw new AuraHandledException(errorMessage);
        }
        return null;
    }
}

@IsTest
private class ErrorStubTest {

    @IsTest
    static void testErrorHandling() {
        // Arrange
        ErrorStub stub = new ErrorStub().failOn('getAccount', 'Account not found');
        IAccountService service = (IAccountService) Test.createStub(
            IAccountService.class,
            stub
        );

        // Act/Assert
        try {
            service.getAccount(null);
            Assert.fail('Expected AuraHandledException');
        } catch (AuraHandledException e) {
            Assert.areEqual('Account not found', e.getMessage());
        }
    }
}

// ═══════════════════════════════════════════════════════════════════════════
// EXAMPLE 5: Universal Mock (Flexible Stub)
// ═══════════════════════════════════════════════════════════════════════════

/**
 * Highly flexible stub that can mock any interface
 *
 * Inspired by: Suraj Pillai's UniversalMock pattern
 */
@IsTest
public class UniversalMock implements System.StubProvider {

    // Store method -> return value mappings
    private Map<String, Object> returnValues = new Map<String, Object>();

    // Store method -> exception mappings
    private Map<String, Exception> exceptions = new Map<String, Exception>();

    // Track all calls
    private List<MethodCall> calls = new List<MethodCall>();

    public class MethodCall {
        public String methodName;
        public List<Object> arguments;
        public Datetime calledAt;

        public MethodCall(String methodName, List<Object> arguments) {
            this.methodName = methodName;
            this.arguments = arguments;
            this.calledAt = Datetime.now();
        }
    }

    /**
     * Configure return value for a method
     */
    public UniversalMock setReturnValue(String methodName, Object value) {
        returnValues.put(methodName, value);
        return this;
    }

    /**
     * Configure exception for a method
     */
    public UniversalMock throwException(String methodName, Exception e) {
        exceptions.put(methodName, e);
        return this;
    }

    public Object handleMethodCall(
        Object stubbedObject,
        String stubbedMethodName,
        Type returnType,
        List<Type> paramTypes,
        List<String> paramNames,
        List<Object> paramValues
    ) {
        // Track the call
        calls.add(new MethodCall(stubbedMethodName, paramValues));

        // Throw configured exception
        if (exceptions.containsKey(stubbedMethodName)) {
            throw exceptions.get(stubbedMethodName);
        }

        // Return configured value
        if (returnValues.containsKey(stubbedMethodName)) {
            return returnValues.get(stubbedMethodName);
        }

        // Return type-appropriate defaults
        if (returnType == Boolean.class) return false;
        if (returnType == Integer.class) return 0;
        if (returnType == String.class) return '';
        if (returnType == List<SObject>.class) return new List<SObject>();

        return null;
    }

    /**
     * Get all calls to a specific method
     */
    public List<MethodCall> getCalls(String methodName) {
        List<MethodCall> result = new List<MethodCall>();
        for (MethodCall call : calls) {
            if (call.methodName == methodName) {
                result.add(call);
            }
        }
        return result;
    }

    /**
     * Verify method was called with specific arguments
     */
    public Boolean wasCalledWith(String methodName, List<Object> expectedArgs) {
        for (MethodCall call : getCalls(methodName)) {
            if (call.arguments.equals(expectedArgs)) {
                return true;
            }
        }
        return false;
    }
}

/**
 * @description Test Data Factory for creating consistent test data across all test classes.
 *              Use this pattern to avoid hardcoded test data and ensure test isolation.
 *
 * USAGE:
 *   List<Account> accounts = TestDataFactory.createAccounts(5);
 *   insert accounts;
 *
 *   // Or with auto-insert:
 *   List<Account> accounts = TestDataFactory.createAndInsertAccounts(5);
 *
 * @created     {{Date}}
 */
@IsTest
public class TestDataFactory {

    // ═══════════════════════════════════════════════════════════════════════════
    // ACCOUNT METHODS
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Creates Account records without inserting
     * @param count Number of accounts to create
     * @return List of Account records (not inserted)
     */
    public static List<Account> createAccounts(Integer count) {
        List<Account> accounts = new List<Account>();
        for (Integer i = 0; i < count; i++) {
            accounts.add(new Account(
                Name = 'Test Account ' + i,
                Industry = 'Technology',
                BillingStreet = '123 Test Street',
                BillingCity = 'San Francisco',
                BillingState = 'CA',
                BillingPostalCode = '94105',
                BillingCountry = 'USA',
                Phone = '555-000-' + String.valueOf(i).leftPad(4, '0'),
                Website = 'https://testaccount' + i + '.example.com'
            ));
        }
        return accounts;
    }

    /**
     * @description Creates and inserts Account records
     * @param count Number of accounts to create
     * @return List of inserted Account records
     */
    public static List<Account> createAndInsertAccounts(Integer count) {
        List<Account> accounts = createAccounts(count);
        insert accounts;
        return accounts;
    }

    /**
     * @description Creates Account with specific attributes
     * @param name Account name
     * @param industry Industry value
     * @return Account record (not inserted)
     */
    public static Account createAccount(String name, String industry) {
        return new Account(
            Name = name,
            Industry = industry,
            BillingCity = 'San Francisco',
            BillingState = 'CA',
            BillingCountry = 'USA'
        );
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // CONTACT METHODS
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Creates Contact records without inserting
     * @param count Number of contacts to create
     * @param accountId Parent account ID
     * @return List of Contact records (not inserted)
     */
    public static List<Contact> createContacts(Integer count, Id accountId) {
        List<Contact> contacts = new List<Contact>();
        for (Integer i = 0; i < count; i++) {
            contacts.add(new Contact(
                FirstName = 'Test',
                LastName = 'Contact ' + i,
                AccountId = accountId,
                Email = 'testcontact' + i + '@example.com',
                Phone = '555-001-' + String.valueOf(i).leftPad(4, '0'),
                Title = 'Test Title ' + i,
                MailingStreet = '456 Test Ave',
                MailingCity = 'San Francisco',
                MailingState = 'CA',
                MailingPostalCode = '94105',
                MailingCountry = 'USA'
            ));
        }
        return contacts;
    }

    /**
     * @description Creates and inserts Contact records
     * @param count Number of contacts to create
     * @param accountId Parent account ID
     * @return List of inserted Contact records
     */
    public static List<Contact> createAndInsertContacts(Integer count, Id accountId) {
        List<Contact> contacts = createContacts(count, accountId);
        insert contacts;
        return contacts;
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // LEAD METHODS
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Creates Lead records without inserting
     * @param count Number of leads to create
     * @return List of Lead records (not inserted)
     */
    public static List<Lead> createLeads(Integer count) {
        List<Lead> leads = new List<Lead>();
        for (Integer i = 0; i < count; i++) {
            leads.add(new Lead(
                FirstName = 'Test',
                LastName = 'Lead ' + i,
                Company = 'Test Company ' + i,
                Email = 'testlead' + i + '@example.com',
                Phone = '555-002-' + String.valueOf(i).leftPad(4, '0'),
                Status = 'Open - Not Contacted',
                Industry = 'Technology',
                LeadSource = 'Web'
            ));
        }
        return leads;
    }

    /**
     * @description Creates and inserts Lead records
     * @param count Number of leads to create
     * @return List of inserted Lead records
     */
    public static List<Lead> createAndInsertLeads(Integer count) {
        List<Lead> leads = createLeads(count);
        insert leads;
        return leads;
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // OPPORTUNITY METHODS
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Creates Opportunity records without inserting
     * @param count Number of opportunities to create
     * @param accountId Parent account ID
     * @return List of Opportunity records (not inserted)
     */
    public static List<Opportunity> createOpportunities(Integer count, Id accountId) {
        List<Opportunity> opportunities = new List<Opportunity>();
        for (Integer i = 0; i < count; i++) {
            opportunities.add(new Opportunity(
                Name = 'Test Opportunity ' + i,
                AccountId = accountId,
                StageName = 'Prospecting',
                CloseDate = Date.today().addDays(30 + i),
                Amount = 10000 * (i + 1)
            ));
        }
        return opportunities;
    }

    /**
     * @description Creates and inserts Opportunity records
     * @param count Number of opportunities to create
     * @param accountId Parent account ID
     * @return List of inserted Opportunity records
     */
    public static List<Opportunity> createAndInsertOpportunities(Integer count, Id accountId) {
        List<Opportunity> opportunities = createOpportunities(count, accountId);
        insert opportunities;
        return opportunities;
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // CASE METHODS
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Creates Case records without inserting
     * @param count Number of cases to create
     * @param accountId Parent account ID (optional)
     * @param contactId Related contact ID (optional)
     * @return List of Case records (not inserted)
     */
    public static List<Case> createCases(Integer count, Id accountId, Id contactId) {
        List<Case> cases = new List<Case>();
        for (Integer i = 0; i < count; i++) {
            cases.add(new Case(
                Subject = 'Test Case ' + i,
                Description = 'Test case description ' + i,
                Status = 'New',
                Priority = 'Medium',
                Origin = 'Web',
                AccountId = accountId,
                ContactId = contactId
            ));
        }
        return cases;
    }

    /**
     * @description Creates and inserts Case records
     * @param count Number of cases to create
     * @param accountId Parent account ID (optional)
     * @param contactId Related contact ID (optional)
     * @return List of inserted Case records
     */
    public static List<Case> createAndInsertCases(Integer count, Id accountId, Id contactId) {
        List<Case> cases = createCases(count, accountId, contactId);
        insert cases;
        return cases;
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // USER METHODS (for System.runAs testing)
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Creates a test User with specified profile
     *              Use with System.runAs() for permission testing
     * @param profileName Name of the profile to assign
     * @param uniqueIdentifier Unique string to avoid duplicate usernames
     * @return User record (not inserted)
     */
    public static User createUser(String profileName, String uniqueIdentifier) {
        Profile p = [SELECT Id FROM Profile WHERE Name = :profileName LIMIT 1];

        String uniqueEmail = uniqueIdentifier + '@testuser.example.com';
        String uniqueUsername = uniqueIdentifier + '@testuser.example.com.test';

        return new User(
            FirstName = 'Test',
            LastName = 'User ' + uniqueIdentifier,
            Email = uniqueEmail,
            Username = uniqueUsername,
            Alias = uniqueIdentifier.left(8),
            ProfileId = p.Id,
            TimeZoneSidKey = 'America/Los_Angeles',
            LocaleSidKey = 'en_US',
            EmailEncodingKey = 'UTF-8',
            LanguageLocaleKey = 'en_US'
        );
    }

    /**
     * @description Creates and inserts a test User
     * @param profileName Name of the profile to assign
     * @param uniqueIdentifier Unique string to avoid duplicate usernames
     * @return Inserted User record
     */
    public static User createAndInsertUser(String profileName, String uniqueIdentifier) {
        User u = createUser(profileName, uniqueIdentifier);
        insert u;
        return u;
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // CUSTOM OBJECT METHODS (Template)
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Template for custom object creation
     *              Copy and modify for your custom objects
     * @param count Number of records to create
     * @return List of custom object records (not inserted)
     */
    /*
    public static List<Custom_Object__c> createCustomObjects(Integer count) {
        List<Custom_Object__c> records = new List<Custom_Object__c>();
        for (Integer i = 0; i < count; i++) {
            records.add(new Custom_Object__c(
                Name = 'Test Record ' + i,
                Custom_Field__c = 'Value ' + i
                // Add more fields as needed
            ));
        }
        return records;
    }

    public static List<Custom_Object__c> createAndInsertCustomObjects(Integer count) {
        List<Custom_Object__c> records = createCustomObjects(count);
        insert records;
        return records;
    }
    */

    // ═══════════════════════════════════════════════════════════════════════════
    // UTILITY METHODS
    // ═══════════════════════════════════════════════════════════════════════════

    /**
     * @description Generates a unique string for test data
     *              Useful for avoiding unique constraint violations
     * @return Unique string based on timestamp
     */
    public static String generateUniqueString() {
        return String.valueOf(Datetime.now().getTime()) +
               String.valueOf(Math.random()).substring(2, 8);
    }

    /**
     * @description Creates a map of records by a specified field
     *              Useful for test assertions
     * @param records List of SObjects
     * @param fieldName API name of the field to use as key
     * @return Map with field values as keys
     */
    public static Map<String, SObject> createMapByField(List<SObject> records, String fieldName) {
        Map<String, SObject> recordMap = new Map<String, SObject>();
        for (SObject record : records) {
            String keyValue = String.valueOf(record.get(fieldName));
            recordMap.put(keyValue, record);
        }
        return recordMap;
    }
}