Pelevin/improve java fuzzing type system (#1594)

Author: Markoutte

utbot-framework/src/main/kotlin/org/utbot/fuzzer/FuzzerFunctions.kt

@@ -74,7 +74,10 @@ fun collectConstantsForFuzzer(graph: ExceptionalUnitGraph): Set<FuzzedConcreteVa
                 try {
                     finder.find(graph, unit, value)
                 } catch (e: Exception) {
-                    logger.warn(e) { "Cannot process constant value of type '${value.type}}'" }
+                    // ignore known values that don't have a value field and can be met
+                    if (value !is NullConstant) {
+                        logger.warn(e) { "Cannot process constant value of type '${value.type}'" }
+                    }
                     emptyList()
                 }
             }.let { result ->

utbot-fuzzers/src/main/kotlin/org/utbot/fuzzer/FuzzedType.kt

@@ -5,16 +5,16 @@ import org.utbot.framework.plugin.api.ClassId
 /**
  * Contains information about classId and generic types, that should be applied.
  *
- * Currently, there's some limitation for generics that are supported:
- * 1. Only concrete types and collections are supported
- * 2. No relative types like: `Map<T, V extends T>`
- *
- * Note, that this class can be replaced by API mechanism for collecting parametrized types,
+ * Note that this class can be replaced by the API mechanism for collecting parametrized types,
  * but at the moment it doesn't fully support all necessary operations.
  *
  * @see ClassId.typeParameters
  */
-data class FuzzedType(
+class FuzzedType(
     val classId: ClassId,
     val generics: List<FuzzedType> = emptyList(),
-)
+) {
+    override fun toString(): String {
+        return "FuzzedType(classId=$classId, generics=${generics.map { it.classId }})"
+    }
+}

utbot-fuzzers/src/main/kotlin/org/utbot/fuzzer/package-info.java

@@ -0,0 +1,7 @@
+/**
+ * @deprecated Code is migrating to the new fuzzing platform.
+ * @see org.utbot.fuzzing.Fuzzing
+ * @see org.utbot.fuzzing.JavaLanguageKt#runJavaFuzzing
+ */
+@Deprecated
+package org.utbot.fuzzer;

utbot-fuzzers/src/main/kotlin/org/utbot/fuzzer/providers/ObjectModelProvider.kt

@@ -24,7 +24,7 @@ import org.utbot.fuzzer.IdentityPreservingIdGenerator
 import org.utbot.fuzzer.objects.FuzzerMockableMethodId
 import org.utbot.fuzzer.objects.assembleModel
 import org.utbot.fuzzing.providers.FieldDescription
-import org.utbot.fuzzing.providers.findAccessibleModifableFields
+import org.utbot.fuzzing.providers.findAccessibleModifiableFields
 import org.utbot.fuzzing.providers.isAccessible
 
 /**
@@ -64,10 +64,10 @@ class ObjectModelProvider(
             // and mutate some fields. Only if there's no option next block
             // with empty constructor should be used.
             if (constructorId.parameters.isEmpty()) {
-                val fields = findAccessibleModifableFields(constructorId.classId, description.packageName)
+                val fields = findAccessibleModifiableFields(null, constructorId.classId, description.packageName)
                 if (fields.isNotEmpty()) {
                     yield(
-                        ModelConstructor(fields.map { FuzzedType(it.classId) }) {
+                        ModelConstructor(fields.map { it.type }) {
                             generateModelsWithFieldsInitialization(constructorId, fields, it)
                         }
                     )
@@ -103,7 +103,7 @@ class ObjectModelProvider(
                         constructorId.classId,
                         field.setter.name,
                         field.setter.returnType.id,
-                        listOf(field.classId),
+                        listOf(field.type.classId),
                         mock = {
                             field.getter?.let { g ->
                                 val getterMethodID = MethodId(

utbot-fuzzers/src/main/kotlin/org/utbot/fuzzing/JavaLanguage.kt

@@ -11,6 +11,7 @@ import org.utbot.fuzzing.utils.Trie
 import java.lang.reflect.*
 import java.util.concurrent.TimeUnit
 import kotlin.system.measureNanoTime
+import kotlin.random.Random
 
 private val logger = KotlinLogging.logger {}
 
@@ -19,6 +20,8 @@ typealias JavaValueProvider = ValueProvider<FuzzedType, FuzzedValue, FuzzedDescr
 class FuzzedDescription(
     val description: FuzzedMethodDescription,
     val tracer: Trie<Instruction, *>,
+    val typeCache: MutableMap<Type, FuzzedType>,
+    val random: Random,
 ) : Description<FuzzedType>(
     description.parameters.mapIndexed { index, classId ->
         description.fuzzerType(index) ?: FuzzedType(classId)
@@ -39,6 +42,7 @@ fun defaultValueProviders(idGenerator: IdentityPreservingIdGenerator<Int>) = lis
     EnumValueProvider(idGenerator),
     ListSetValueProvider(idGenerator),
     MapValueProvider(idGenerator),
+    IteratorValueProvider(idGenerator),
     EmptyCollectionValueProvider(idGenerator),
     DateValueProvider(idGenerator),
 //    NullValueProvider,
@@ -52,13 +56,18 @@ suspend fun runJavaFuzzing(
     providers: List<ValueProvider<FuzzedType, FuzzedValue, FuzzedDescription>> = defaultValueProviders(idGenerator),
     exec: suspend (thisInstance: FuzzedValue?, description: FuzzedDescription, values: List<FuzzedValue>) -> BaseFeedback<Trie.Node<Instruction>, FuzzedType, FuzzedValue>
 ) {
+    val random = Random(0)
     val classUnderTest = methodUnderTest.classId
     val name = methodUnderTest.classId.simpleName + "." + methodUnderTest.name
     val returnType = methodUnderTest.returnType
     val parameters = methodUnderTest.parameters
 
+    // For a concrete fuzzing run we need to track types we create.
+    // Because of generics can be declared as recursive structures like `<T extends Iterable<T>>`,
+    // we should track them by reference and do not call `equals` and `hashCode` recursively.
+    val typeCache = hashMapOf<Type, FuzzedType>()
     /**
-     * To fuzz this instance the class of it is added into head of parameters list.
+     * To fuzz this instance, the class of it is added into head of parameters list.
      * Done for compatibility with old fuzzer logic and should be reworked more robust way.
      */
     fun createFuzzedMethodDescription(self: ClassId?) = FuzzedMethodDescription(
@@ -79,9 +88,9 @@ suspend fun runJavaFuzzing(
         fuzzerType = {
             try {
                 when {
-                    self != null && it == 0 -> toFuzzerType(methodUnderTest.executable.declaringClass)
-                    self != null -> toFuzzerType(methodUnderTest.executable.genericParameterTypes[it - 1])
-                    else -> toFuzzerType(methodUnderTest.executable.genericParameterTypes[it])
+                    self != null && it == 0 -> toFuzzerType(methodUnderTest.executable.declaringClass, typeCache)
+                    self != null -> toFuzzerType(methodUnderTest.executable.genericParameterTypes[it - 1], typeCache)
+                    else -> toFuzzerType(methodUnderTest.executable.genericParameterTypes[it], typeCache)
                 }
             } catch (_: Throwable) {
                 null
@@ -94,15 +103,15 @@ suspend fun runJavaFuzzing(
         if (!isStatic && !isConstructor) { classUnderTest } else { null }
     }
     val tracer = Trie(Instruction::id)
-    val descriptionWithOptionalThisInstance = FuzzedDescription(createFuzzedMethodDescription(thisInstance), tracer)
-    val descriptionWithOnlyParameters = FuzzedDescription(createFuzzedMethodDescription(null), tracer)
+    val descriptionWithOptionalThisInstance = FuzzedDescription(createFuzzedMethodDescription(thisInstance), tracer, typeCache, random)
+    val descriptionWithOnlyParameters = FuzzedDescription(createFuzzedMethodDescription(null), tracer, typeCache, random)
     try {
         logger.info { "Starting fuzzing for method: $methodUnderTest" }
         logger.info { "\tuse thisInstance = ${thisInstance != null}" }
         logger.info { "\tparameters = $parameters" }
         var totalExecutionCalled = 0
         val totalFuzzingTime = measureNanoTime {
-            runFuzzing(ValueProvider.of(providers), descriptionWithOptionalThisInstance) { _, t ->
+            runFuzzing(ValueProvider.of(providers), descriptionWithOptionalThisInstance, random) { _, t ->
                 totalExecutionCalled++
                 if (thisInstance == null) {
                     exec(null, descriptionWithOnlyParameters, t)
@@ -118,22 +127,86 @@ suspend fun runJavaFuzzing(
     }
 }
 
-private fun toFuzzerType(type: Type): FuzzedType {
+/**
+ * Resolve a fuzzer type that has class info and some generics.
+ *
+ * @param type to be resolved
+ * @param cache is used to store same [FuzzedType] for same java types
+ */
+internal fun toFuzzerType(type: Type, cache: MutableMap<Type, FuzzedType>): FuzzedType {
+    return toFuzzerType(
+        type = type,
+        classId = { t -> toClassId(t, cache) },
+        generics = { t -> toGenerics(t) },
+        cache = cache,
+    )
+}
+
+/**
+ * Resolve a fuzzer type that has class info and some generics.
+ *
+ * Cache is used to stop recursive call in case of some recursive class definition like:
+ *
+ * ```
+ * public <T extends Iterable<T>> call(T type) { ... }
+ * ```
+ *
+ * @param type to be resolved into a fuzzed type.
+ * @param classId is a function that produces classId by general type.
+ * @param generics is a function that produced a list of generics for this concrete type.
+ * @param cache is used to store all generated types.
+ */
+private fun toFuzzerType(
+    type: Type,
+    classId: (type: Type) -> ClassId,
+    generics: (parent: Type) -> Array<out Type>,
+    cache: MutableMap<Type, FuzzedType>
+): FuzzedType {
+    val g = mutableListOf<FuzzedType>()
+    val t = type.replaceWithUpperBoundUntilNotTypeVariable()
+    var target = cache[t]
+    if (target == null) {
+        target = FuzzedType(classId(t), g)
+        cache[t] = target
+        g += generics(t).map {
+            toFuzzerType(it, classId, generics, cache)
+        }
+    }
+    return target
+}
+
+internal fun Type.replaceWithUpperBoundUntilNotTypeVariable() : Type {
+    var type: Type = this
+    while (type is TypeVariable<*>) {
+        type = type.bounds.firstOrNull() ?: java.lang.Object::class.java
+    }
+    return type
+}
+
+private fun toClassId(type: Type, cache: MutableMap<Type, FuzzedType>): ClassId {
     return when (type) {
-        is WildcardType -> type.upperBounds.firstOrNull()?.let(::toFuzzerType) ?: FuzzedType(objectClassId)
-        is TypeVariable<*> -> type.bounds.firstOrNull()?.let(::toFuzzerType) ?: FuzzedType(objectClassId)
-        is ParameterizedType -> FuzzedType((type.rawType as Class<*>).id, type.actualTypeArguments.map { toFuzzerType(it) })
+        is WildcardType -> type.upperBounds.firstOrNull()?.let { toClassId(it, cache) } ?: objectClassId
         is GenericArrayType -> {
             val genericComponentType = type.genericComponentType
-            val fuzzerType = toFuzzerType(genericComponentType)
-            val classId = if (genericComponentType !is GenericArrayType) {
-                ClassId("[L${fuzzerType.classId.name};", fuzzerType.classId)
+            val classId = toFuzzerType(genericComponentType, cache).classId
+            if (genericComponentType !is GenericArrayType) {
+                ClassId("[L${classId.name};", classId)
             } else {
-                ClassId("[" + fuzzerType.classId.name, fuzzerType.classId)
+                ClassId("[" + classId.name, classId)
             }
-            FuzzedType(classId)
         }
-        is Class<*> -> FuzzedType(type.id, type.typeParameters.map { toFuzzerType(it) })
-        else -> error("Unknown type: $type")
+        is ParameterizedType -> (type.rawType as Class<*>).id
+        is Class<*> -> type.id
+        else -> error("unknown type: $type")
+    }
+}
+
+private fun toGenerics(t: Type) : Array<out Type> {
+    return when (t) {
+        is WildcardType -> t.upperBounds.firstOrNull()?.let { toGenerics(it) } ?: emptyArray()
+        is GenericArrayType -> arrayOf(t.genericComponentType)
+        is ParameterizedType -> t.actualTypeArguments
+        is Class<*> -> t.typeParameters
+        else -> emptyArray()
     }
 }

utbot-fuzzers/src/main/kotlin/org/utbot/fuzzing/providers/Arrays.kt

@@ -7,10 +7,7 @@ import org.utbot.fuzzer.FuzzedType
 import org.utbot.fuzzer.FuzzedValue
 import org.utbot.fuzzer.IdGenerator
 import org.utbot.fuzzer.providers.ConstantsModelProvider.fuzzed
-import org.utbot.fuzzing.FuzzedDescription
-import org.utbot.fuzzing.Routine
-import org.utbot.fuzzing.Seed
-import org.utbot.fuzzing.ValueProvider
+import org.utbot.fuzzing.*
 
 class ArrayValueProvider(
     val idGenerator: IdGenerator<Int>,
@@ -35,9 +32,24 @@ class ArrayValueProvider(
                         summary = "%var% = ${type.classId.elementClassId!!.simpleName}[$it]"
                     }
                 },
-                modify = Routine.ForEach(listOf(FuzzedType(type.classId.elementClassId!!))) { self, i, values ->
+                modify = Routine.ForEach(listOf(resolveArrayElementType(type))) { self, i, values ->
                     (self.model as UtArrayModel).stores[i] = values.first().model
                 }
             ))
     }
+
+    /**
+     * Resolves array's element type. In case a generic type is used, like `T[]` the type should pass generics.
+     *
+     * For example, List<Number>[] returns List<Number>.
+     */
+    private fun resolveArrayElementType(arrayType: FuzzedType): FuzzedType = when {
+        !arrayType.classId.isArray -> error("$arrayType is not array")
+        arrayType.generics.size == 1 -> arrayType.generics.first()
+        arrayType.generics.isEmpty() -> FuzzedType(
+            arrayType.classId.elementClassId ?: error("Element classId of $arrayType is not found")
+        )
+
+        else -> error("Array has ${arrayType.generics.size} generic type for ($arrayType), that should not happen")
+    }
 }

utbot-fuzzers/src/main/kotlin/org/utbot/fuzzing/providers/Collections.kt

@@ -6,10 +6,8 @@ import org.utbot.fuzzer.FuzzedType
 import org.utbot.fuzzer.FuzzedValue
 import org.utbot.fuzzer.IdGenerator
 import org.utbot.fuzzer.providers.PrimitivesModelProvider.fuzzed
-import org.utbot.fuzzing.FuzzedDescription
-import org.utbot.fuzzing.Routine
-import org.utbot.fuzzing.Seed
-import org.utbot.fuzzing.ValueProvider
+import org.utbot.fuzzing.*
+import org.utbot.fuzzing.utils.hex
 import kotlin.reflect.KClass
 
 class EmptyCollectionValueProvider(
@@ -56,10 +54,25 @@ class EmptyCollectionValueProvider(
                     classId = classId,
                     modelName = "",
                     instantiationCall = UtExecutableCallModel(null, executableId, value.map { it.model })
+                ).fuzzed {
+                    summary = "%var% = ${executableId.classId.simpleName}#${executableId.name}"
+                }
+            },
+            empty = Routine.Empty {
+                if (executableId.parameters.isEmpty())  {
+                    UtAssembleModel(
+                        id = idGenerator.createId(),
+                        classId = classId,
+                        modelName = "",
+                        instantiationCall = UtExecutableCallModel(null, executableId, emptyList())
 
-                ).fuzzed()
+                    ).fuzzed{
+                        summary = "%var% = ${executableId.classId.simpleName}#${executableId.name}"
+                    }
+                } else {
+                    UtNullModel(classId).fuzzed { summary = "%var% = null" }
+                }
             },
-            empty = Routine.Empty { UtNullModel(classId).fuzzed { summary = "%var% = null" } }
         ))
     }
 }
@@ -205,4 +218,51 @@ abstract class CollectionValueProvider(
 //        return isSubtypeOf(another)
         return klass.java.isAssignableFrom(this.jClass)
     }
+}
+
+class IteratorValueProvider(val idGenerator: IdGenerator<Int>) : ValueProvider<FuzzedType, FuzzedValue, FuzzedDescription> {
+    override fun accept(type: FuzzedType): Boolean {
+        return type.classId == Iterator::class.id
+    }
+
+    override fun generate(description: FuzzedDescription, type: FuzzedType): Sequence<Seed<FuzzedType, FuzzedValue>> {
+        val generic = type.generics.firstOrNull() ?: FuzzedType(objectClassId)
+        return sequenceOf(Seed.Recursive(
+            construct = Routine.Create(listOf(FuzzedType(iterableClassId, listOf(generic)))) { v ->
+                val id = idGenerator.createId()
+                val iterable = when (val model = v.first().model) {
+                    is UtAssembleModel -> model
+                    is UtNullModel -> return@Create v.first()
+                    else -> error("Model can be only UtNullModel or UtAssembleModel, but $model is met")
+                }
+                UtAssembleModel(
+                    id = id,
+                    classId = type.classId,
+                    modelName = "iterator#${id.hex()}",
+                    instantiationCall = UtExecutableCallModel(
+                        instance = iterable,
+                        executable = MethodId(iterableClassId, "iterator", type.classId, emptyList()),
+                        params = emptyList()
+                    )
+                ).fuzzed {
+                    summary = "%var% = ${iterable.classId.simpleName}#iterator()"
+                }
+            },
+            empty = Routine.Empty {
+                val id = idGenerator.createId()
+                UtAssembleModel(
+                    id = id,
+                    classId = type.classId,
+                    modelName = "emptyIterator#${id.hex()}",
+                    instantiationCall = UtExecutableCallModel(
+                        instance = null,
+                        executable = MethodId(java.util.Collections::class.id, "emptyIterator", type.classId, emptyList()),
+                        params = emptyList()
+                    )
+                ).fuzzed {
+                    summary = "%var% = empty iterator"
+                }
+            }
+        ))
+    }
 }