Framework Integration

/**
 * Interface that abstracts the assertion logic and can be implemented by 
 * any testing framework to provide consistent assertion behavior across platforms.
 */
interface Asserter {
    /**
     * Marks a test as failed with the specified message.
     * @param message The failure message, or null for default message
     * @return Nothing (this function never returns normally)
     */
    fun fail(message: String?): Nothing
    
    /**
     * Marks a test as failed with the specified message and cause.
     * @param message The failure message, or null for default message  
     * @param cause The underlying cause of the failure, or null if none
     * @return Nothing (this function never returns normally)
     */
    fun fail(message: String?, cause: Throwable?): Nothing
    
    /**
     * Asserts that the value is true.
     * @param lazyMessage Lazy-evaluated message provider for failure cases
     * @param actual The boolean value to test
     */
    fun assertTrue(lazyMessage: () -> String?, actual: Boolean)
    
    /**
     * Asserts that the value is true.
     * @param message The failure message, or null for default
     * @param actual The boolean value to test
     */
    fun assertTrue(message: String?, actual: Boolean)
    
    /**
     * Asserts that the expected and actual values are equal.
     * @param message The failure message, or null for default
     * @param expected The expected value
     * @param actual The actual value to compare
     */
    fun assertEquals(message: String?, expected: Any?, actual: Any?)
    
    /**
     * Asserts that the illegal and actual values are not equal.
     * @param message The failure message, or null for default
     * @param illegal The value that should not match
     * @param actual The actual value to compare
     */
    fun assertNotEquals(message: String?, illegal: Any?, actual: Any?)
    
    /**
     * Asserts that the expected and actual references are the same instance.
     * @param message The failure message, or null for default
     * @param expected The expected object reference
     * @param actual The actual object reference
     */
    fun assertSame(message: String?, expected: Any?, actual: Any?)
    
    /**
     * Asserts that the illegal and actual references are not the same instance.
     * @param message The failure message, or null for default
     * @param illegal The reference that should not match
     * @param actual The actual object reference
     */
    fun assertNotSame(message: String?, illegal: Any?, actual: Any?)
    
    /**
     * Asserts that the actual value is null.
     * @param message The failure message, or null for default
     * @param actual The value to test for null
     */
    fun assertNull(message: String?, actual: Any?)
    
    /**
     * Asserts that the actual value is not null.
     * @param message The failure message, or null for default
     * @param actual The value to test for non-null
     */
    fun assertNotNull(message: String?, actual: Any?)
}

/**
 * Interface for providing Asserter instances. Implementations can be registered
 * to contribute custom assertion behavior for specific testing frameworks.
 */
interface AsserterContributor {
    /**
     * Provides an Asserter instance for the current testing context.
     * @return An Asserter implementation, or null if this contributor 
     *         cannot provide one for the current context
     */
    fun contribute(): Asserter?
}

/**
 * The current Asserter instance used by all assertion functions.
 * This can be replaced to integrate with different testing frameworks.
 * Defaults to DefaultAsserter if no framework-specific asserter is available.
 */
var asserter: Asserter

import kotlin.test.*

@Test
fun testCustomAsserterIntegration() {
    // Save the original asserter
    val originalAsserter = asserter
    
    try {
        // Install a custom asserter for specialized behavior
        asserter = CustomTestAsserter()
        
        // All assertions now use the custom asserter
        assertEquals("expected", "actual") // Uses CustomTestAsserter.assertEquals()
        assertTrue(false) // Uses CustomTestAsserter.assertTrue()
        
    } finally {
        // Restore original asserter
        asserter = originalAsserter
    }
}

class CustomTestAsserter : Asserter {
    override fun fail(message: String?): Nothing {
        throw CustomAssertionError(message ?: "Assertion failed")
    }
    
    override fun fail(message: String?, cause: Throwable?): Nothing {
        throw CustomAssertionError(message ?: "Assertion failed", cause)
    }
    
    override fun assertTrue(message: String?, actual: Boolean) {
        if (!actual) {
            fail(message ?: "Expected true but was false")
        }
    }
    
    override fun assertEquals(message: String?, expected: Any?, actual: Any?) {
        if (expected != actual) {
            fail(message ?: "Expected <$expected> but was <$actual>")
        }
    }
    
    // ... implement other methods
}

/**
 * Default Asserter implementation that provides basic assertion functionality
 * without depending on any specific testing framework.
 */
object DefaultAsserter : Asserter {
    /**
     * Throws AssertionError with the specified message.
     */
    override fun fail(message: String?): Nothing
    
    /**
     * Throws AssertionErrorWithCause with the specified message and cause.
     */
    override fun fail(message: String?, cause: Throwable?): Nothing
}

// Custom JUnit asserter implementation
class JUnitAsserter : Asserter {
    override fun fail(message: String?): Nothing {
        org.junit.Assert.fail(message)
        throw AssertionError() // Never reached
    }
    
    override fun assertTrue(message: String?, actual: Boolean) {
        org.junit.Assert.assertTrue(message, actual)
    }
    
    override fun assertEquals(message: String?, expected: Any?, actual: Any?) {
        org.junit.Assert.assertEquals(message, expected, actual)
    }
    
    // ... other implementations delegate to JUnit
}

// Register the asserter
class JUnitAsserterContributor : AsserterContributor {
    override fun contribute(): Asserter? {
        return if (isJUnitAvailable()) JUnitAsserter() else null
    }
    
    private fun isJUnitAvailable(): Boolean {
        return try {
            Class.forName("org.junit.Assert")
            true
        } catch (e: ClassNotFoundException) {
            false
        }
    }
}

// Custom JavaScript asserter for Node.js environments
class NodeJSAsserter : Asserter {
    override fun fail(message: String?): Nothing {
        js("throw new Error(message || 'Assertion failed')")
    }
    
    override fun assertTrue(message: String?, actual: Boolean) {
        if (!actual) {
            fail(message ?: "Expected true but was false")
        }
    }
    
    override fun assertEquals(message: String?, expected: Any?, actual: Any?) {
        js("""
            const assert = require('assert');
            assert.deepStrictEqual(actual, expected, message);
        """)
    }
    
    // ... other implementations
}

// Custom native asserter implementation
class NativeAsserter : Asserter {
    override fun fail(message: String?): Nothing {
        // Native-specific error reporting
        platform.posix.fprintf(platform.posix.stderr, "ASSERTION FAILED: %s\n", message ?: "")
        platform.posix.exit(1)
        throw AssertionError() // Never reached
    }
    
    // ... other implementations using native APIs
}

import kotlin.test.*

// Step 1: Implement the Asserter interface
class MyFrameworkAsserter : Asserter {
    override fun fail(message: String?): Nothing {
        MyTestFramework.reportFailure(message ?: "Test failed")
        throw MyFrameworkException(message)
    }
    
    override fun fail(message: String?, cause: Throwable?): Nothing {
        MyTestFramework.reportFailure(message ?: "Test failed", cause)
        throw MyFrameworkException(message, cause)
    }
    
    override fun assertTrue(message: String?, actual: Boolean) {
        if (!actual) {
            MyTestFramework.reportBooleanFailure(message, expected = true, actual = false)
            fail(message ?: "Expected true but was false")
        }
    }
    
    override fun assertEquals(message: String?, expected: Any?, actual: Any?) {
        if (expected != actual) {
            MyTestFramework.reportEqualityFailure(message, expected, actual)
            fail(message ?: "Expected <$expected> but was <$actual>")
        }
    }
    
    // Implement remaining methods...
}

// Step 2: Create an AsserterContributor
class MyFrameworkAsserterContributor : AsserterContributor {
    override fun contribute(): Asserter? {
        return if (MyTestFramework.isActive()) {
            MyFrameworkAsserter()
        } else {
            null
        }
    }
}

// Step 3: Register the contributor (usually done during framework initialization)
fun initializeMyFramework() {
    val contributor = MyFrameworkAsserterContributor()
    val customAsserter = contributor.contribute()
    if (customAsserter != null) {
        asserter = customAsserter
    }
}

// Enhanced asserter with additional framework-specific features
class EnhancedFrameworkAsserter : Asserter {
    private val testContext = MyFramework.getCurrentTestContext()
    
    override fun fail(message: String?): Nothing {
        // Capture additional context
        val stackTrace = Thread.currentThread().stackTrace
        val testMethod = stackTrace.find { it.methodName.startsWith("test") }
        
        MyFramework.reportDetailedFailure(
            message = message,
            testClass = testContext.testClass,
            testMethod = testMethod?.methodName,
            stackTrace = stackTrace
        )
        
        throw MyFrameworkException(message)
    }
    
    // Override other methods with enhanced reporting...
    
    override fun assertEquals(message: String?, expected: Any?, actual: Any?) {
        if (expected != actual) {
            // Enhanced diff reporting
            val diff = MyFramework.computeDiff(expected, actual)
            MyFramework.reportEqualityFailure(
                message = message,
                expected = expected,
                actual = actual,
                diff = diff
            )
            fail(buildEqualityMessage(message, expected, actual, diff))
        }
    }
    
    private fun buildEqualityMessage(
        userMessage: String?,
        expected: Any?,
        actual: Any?,
        diff: String
    ): String {
        val base = userMessage ?: "Assertion failed"
        return "$base\nExpected: $expected\nActual: $actual\nDiff:\n$diff"
    }
}

@Test
fun testFrameworkFallback() {
    // This test works regardless of which testing framework is present
    assertEquals("expected", computeValue())
    assertTrue(isValid())
    
    // The underlying asserter handles framework-specific reporting
}