#152 support value classes

agent/android/src/main/kotlin/io/mockk/ValueClassSupport.kt

@@ -6,80 +6,60 @@ import kotlin.reflect.full.declaredMemberProperties
 import kotlin.reflect.full.primaryConstructor
 import kotlin.reflect.jvm.isAccessible
 
-private val valueClassFieldCache = mutableMapOf<KClass<out Any>, KProperty1<out Any, *>>()
+// TODO this class is copy-pasted and should be de-duplicated
+//      see https://github.com/mockk/mockk/issues/857
 
 /**
- * Get boxed value of any value class
+ * Underlying property value of a **`value class`** or self.
  *
- * @return boxed value of value class, if this is value class, else just itself
+ * The type of the return might also be a `value class`!
  */
-fun <T : Any> T.boxedValue(): Any? {
-    if (!this::class.isValueClass()) return this
-
-    // get backing field
-    val backingField = this::class.valueField()
-
-    // get boxed value
+val <T : Any> T.boxedValue: Any?
     @Suppress("UNCHECKED_CAST")
-    return (backingField as KProperty1<T, *>).get(this)
-}
+    get() = if (!this::class.isValue_safe) {
+        this
+    } else {
+        (this::class as KClass<T>).boxedProperty.get(this)
+    }
 
 /**
- * Get class of boxed value of any value class
+ * Underlying property class of a **`value class`** or self.
  *
- * @return class of boxed value, if this is value class, else just class of itself
+ * The returned class might also be a `value class`!
  */
-fun <T : Any> T.boxedClass(): KClass<*> {
-    return this::class.boxedClass()
-}
+val KClass<*>.boxedClass: KClass<*>
+    get() = if (!this.isValue_safe) {
+        this
+    } else {
+        this.boxedProperty.returnType.classifier as KClass<*>
+    }
+
+private val valueClassFieldCache = mutableMapOf<KClass<out Any>, KProperty1<out Any, *>>()
 
 /**
- * Get the KClass of boxed value if this is a value class.
+ * Underlying property of a **`value class`**.
  *
- * @return class of boxed value, if this is value class, else just class of itself
+ * The underlying property might also be a `value class`!
  */
-fun KClass<*>.boxedClass(): KClass<*> {
-    if (!this.isValueClass()) return this
-
-    // get backing field
-    val backingField = this.valueField()
-
-    // get boxed value
-    return backingField.returnType.classifier as KClass<*>
-}
-
-
-private fun <T : Any> KClass<T>.valueField(): KProperty1<out T, *> {
-    @Suppress("UNCHECKED_CAST")
-    return valueClassFieldCache.getOrPut(this) {
-        require(isValue) { "$this is not a value class" }
-
-        // value classes always have a primary constructor...
-        val constructor = primaryConstructor!!
-        // ...and exactly one constructor parameter
-        val constructorParameter = constructor.parameters.first()
-        // ...with a backing field
-        val backingField = declaredMemberProperties
-            .first { it.name == constructorParameter.name }
-            .apply { isAccessible = true }
-
-        backingField
-    } as KProperty1<out T, *>
-}
-
-private fun <T : Any> KClass<T>.isValueClass() = try {
-    this.isValue
-} catch (_: Throwable) {
-    false
-}
+private val <T : Any> KClass<T>.boxedProperty: KProperty1<T, *>
+    get() = if (!this.isValue_safe) {
+        throw UnsupportedOperationException("$this is not a value class")
+    } else {
+        // value classes always have exactly one property
+        @Suppress("UNCHECKED_CAST")
+        valueClassFieldCache.getOrPut(this) {
+            this.declaredMemberProperties.first().apply { isAccessible = true }
+        } as KProperty1<T, *>
+    }
 
 /**
- * POLYFILL for kotlin version < 1.5
- * will be shadowed by implementation in kotlin SDK 1.5+
+ * Returns `true` if calling [KClass.isValue] is safe.
  *
- * @return true if this is an inline class, else false
+ * (In some instances [KClass.isValue] can throw an exception.)
  */
-private val <T : Any> KClass<T>.isValue: Boolean
-    get() = !isData &&
-            primaryConstructor?.parameters?.size == 1 &&
-            java.declaredMethods.any { it.name == "box-impl" }
+private val <T : Any> KClass<T>.isValue_safe: Boolean
+    get() = try {
+        this.isValue
+    } catch (_: UnsupportedOperationException) {
+        false
+    }

agent/android/src/main/kotlin/io/mockk/proxy/android/advice/Advice.kt

@@ -81,7 +81,7 @@ internal class Advice(
                 superMethodCall,
                 arguments
             )
-                ?.boxedValue() // unbox value class objects
+                ?.boxedValue // unbox value class objects
         }
     }
 

agent/jvm/src/main/kotlin/io/mockk/ValueClassSupport.kt

@@ -6,80 +6,60 @@ import kotlin.reflect.full.declaredMemberProperties
 import kotlin.reflect.full.primaryConstructor
 import kotlin.reflect.jvm.isAccessible
 
-private val valueClassFieldCache = mutableMapOf<KClass<out Any>, KProperty1<out Any, *>>()
+// TODO this class is copy-pasted and should be de-duplicated
+//      see https://github.com/mockk/mockk/issues/857
 
 /**
- * Get boxed value of any value class
+ * Underlying property value of a **`value class`** or self.
  *
- * @return boxed value of value class, if this is value class, else just itself
+ * The type of the return might also be a `value class`!
  */
-fun <T : Any> T.boxedValue(): Any? {
-    if (!this::class.isValueClass()) return this
-
-    // get backing field
-    val backingField = this::class.valueField()
-
-    // get boxed value
+val <T : Any> T.boxedValue: Any?
     @Suppress("UNCHECKED_CAST")
-    return (backingField as KProperty1<T, *>).get(this)
-}
+    get() = if (!this::class.isValue_safe) {
+        this
+    } else {
+        (this::class as KClass<T>).boxedProperty.get(this)
+    }
 
 /**
- * Get class of boxed value of any value class
+ * Underlying property class of a **`value class`** or self.
  *
- * @return class of boxed value, if this is value class, else just class of itself
+ * The returned class might also be a `value class`!
  */
-fun <T : Any> T.boxedClass(): KClass<*> {
-    return this::class.boxedClass()
-}
+val KClass<*>.boxedClass: KClass<*>
+    get() = if (!this.isValue_safe) {
+        this
+    } else {
+        this.boxedProperty.returnType.classifier as KClass<*>
+    }
+
+private val valueClassFieldCache = mutableMapOf<KClass<out Any>, KProperty1<out Any, *>>()
 
 /**
- * Get the KClass of boxed value if this is a value class.
+ * Underlying property of a **`value class`**.
  *
- * @return class of boxed value, if this is value class, else just class of itself
+ * The underlying property might also be a `value class`!
  */
-fun KClass<*>.boxedClass(): KClass<*> {
-    if (!this.isValueClass()) return this
-
-    // get backing field
-    val backingField = this.valueField()
-
-    // get boxed value
-    return backingField.returnType.classifier as KClass<*>
-}
-
-
-private fun <T : Any> KClass<T>.valueField(): KProperty1<out T, *> {
-    @Suppress("UNCHECKED_CAST")
-    return valueClassFieldCache.getOrPut(this) {
-        require(isValue) { "$this is not a value class" }
-
-        // value classes always have a primary constructor...
-        val constructor = primaryConstructor!!
-        // ...and exactly one constructor parameter
-        val constructorParameter = constructor.parameters.first()
-        // ...with a backing field
-        val backingField = declaredMemberProperties
-            .first { it.name == constructorParameter.name }
-            .apply { isAccessible = true }
-
-        backingField
-    } as KProperty1<out T, *>
-}
-
-private fun <T : Any> KClass<T>.isValueClass() = try {
-    this.isValue
-} catch (_: Throwable) {
-    false
-}
+private val <T : Any> KClass<T>.boxedProperty: KProperty1<T, *>
+    get() = if (!this.isValue_safe) {
+        throw UnsupportedOperationException("$this is not a value class")
+    } else {
+        // value classes always have exactly one property
+        @Suppress("UNCHECKED_CAST")
+        valueClassFieldCache.getOrPut(this) {
+            this.declaredMemberProperties.first().apply { isAccessible = true }
+        } as KProperty1<T, *>
+    }
 
 /**
- * POLYFILL for kotlin version < 1.5
- * will be shadowed by implementation in kotlin SDK 1.5+
+ * Returns `true` if calling [KClass.isValue] is safe.
  *
- * @return true if this is an inline class, else false
+ * (In some instances [KClass.isValue] can throw an exception.)
  */
-private val <T : Any> KClass<T>.isValue: Boolean
-    get() = !isData &&
-            primaryConstructor?.parameters?.size == 1 &&
-            java.declaredMethods.any { it.name == "box-impl" }
+private val <T : Any> KClass<T>.isValue_safe: Boolean
+    get() = try {
+        this.isValue
+    } catch (_: UnsupportedOperationException) {
+        false
+    }

agent/jvm/src/main/kotlin/io/mockk/proxy/jvm/advice/Interceptor.kt

@@ -19,7 +19,7 @@ internal class Interceptor(
             method
         )
         return handler.invocation(self, method, callOriginalMethod, arguments)
-            ?.boxedValue() // unbox value class objects
+            ?.boxedValue // unbox value class objects
     }
 
 }

build.gradle

@@ -1,3 +1,5 @@
+import java.time.Duration
+
 buildscript {
     ext.kotlin_gradle_version = findProperty('kotlin.version')?.toString() ?: '1.6.0'
     ext.android_gradle_version = '7.0.0'
@@ -44,4 +46,8 @@ subprojects { subProject ->
             languageVersion = "1.5"
         }
     }
+
+    tasks.withType(Test).configureEach {
+        timeout.set(Duration.ofMinutes(5))
+    }
 }

dsl/common/src/main/kotlin/io/mockk/API.kt

@@ -3557,11 +3557,13 @@ interface TypedMatcher {
     val argumentType: KClass<*>
 
     fun checkType(arg: Any?): Boolean {
-        if (argumentType.simpleName === null) {
-            return true
+        return when {
+            argumentType.simpleName === null -> true
+            else -> {
+                val unboxedClass = InternalPlatformDsl.unboxClass(argumentType)
+                return unboxedClass.isInstance(arg)
+            }
         }
-
-        return argumentType.isInstance(arg)
     }
 }
 

dsl/common/src/main/kotlin/io/mockk/InternalPlatformDsl.kt

@@ -1,6 +1,7 @@
 package io.mockk
 
 import kotlin.coroutines.Continuation
+import kotlin.reflect.KClass
 
 expect object InternalPlatformDsl {
     fun identityHashCode(obj: Any): Int
@@ -35,6 +36,26 @@ expect object InternalPlatformDsl {
     fun counter(): InternalCounter
 
     fun <T> coroutineCall(lambda: suspend () -> T): CoroutineCall<T>
+
+    /**
+     * Get the [KClass] of the single value that a `value class` contains.
+     *
+     * The result might also be a value class! So check recursively, if necessary.
+     *
+     * @return [KClass] of boxed value, if this is `value class`, else [cls].
+     */
+    fun unboxClass(cls: KClass<*>): KClass<*>
+
+    /**
+     * Normally this simply casts [arg] to `T`
+     *
+     * However, if `T` is a `value class` (of type [cls]) this will construct a new instance of the
+     * value class, and set [arg] as the value.
+     */
+     fun <T : Any> boxCast(
+        cls: KClass<*>,
+        arg: Any,
+    ): T
 }
 
 interface CoroutineCall<T> {
@@ -50,4 +71,4 @@ interface InternalCounter {
     val value: Long
 
     fun increment(): Long
-}
+}

dsl/common/src/main/kotlin/io/mockk/Matchers.kt

@@ -140,17 +140,16 @@ data class CaptureNullableMatcher<T : Any>(
  */
 data class CapturingSlotMatcher<T : Any>(
     val captureSlot: CapturingSlot<T>,
-    override val argumentType: KClass<*>
+    override val argumentType: KClass<*>,
 ) : Matcher<T>, CapturingMatcher, TypedMatcher, EquivalentMatcher {
     override fun equivalent(): Matcher<Any> = ConstantMatcher<Any>(true)
 
-    @Suppress("UNCHECKED_CAST")
     override fun capture(arg: Any?) {
         if (arg == null) {
             captureSlot.isNull = true
         } else {
             captureSlot.isNull = false
-            captureSlot.captured = arg as T
+            captureSlot.captured = InternalPlatformDsl.boxCast(argumentType, arg)
         }
         captureSlot.isCaptured = true
     }
@@ -473,4 +472,3 @@ fun CompositeMatcher<*>.captureSubMatchers(arg: Any?) {
             .forEach { it.capture(arg) }
     }
 }
-