Improve fuzzer recursive model providers (#1039)

Author: Markoutte

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

@@ -12,23 +12,28 @@ import org.utbot.fuzzer.fuzzNumbers
 
 class ArrayModelProvider(
     idGenerator: IdentityPreservingIdGenerator<Int>,
-    recursionDepthLeft: Int = 1
+    recursionDepthLeft: Int = 2
 ) : RecursiveModelProvider(idGenerator, recursionDepthLeft) {
 
-    override fun newInstance(parentProvider: RecursiveModelProvider): RecursiveModelProvider =
-        ArrayModelProvider(parentProvider.idGenerator, parentProvider.recursionDepthLeft - 1)
-            .copySettings(parentProvider)
+    override fun newInstance(parentProvider: RecursiveModelProvider, constructor: ModelConstructor): RecursiveModelProvider {
+        val provider = ArrayModelProvider(parentProvider.idGenerator, parentProvider.recursionDepthLeft - 1)
+        provider.copySettings(parentProvider)
+        provider.totalLimit = minOf(parentProvider.totalLimit, constructor.limit)
+        return provider
+    }
 
     override fun generateModelConstructors(
         description: FuzzedMethodDescription,
         parameterIndex: Int,
         classId: ClassId,
     ): Sequence<ModelConstructor> = sequence {
         if (!classId.isArray) return@sequence
-        val lengths = fuzzNumbers(description.concreteValues, 0, 3) { it in 1..10 }
+        val lengths = fuzzNumbers(description.concreteValues, 0, 3) { it in 1..10 }.toList()
         lengths.forEach { length ->
             yield(ModelConstructor(listOf(FuzzedType(classId.elementClassId!!)), repeat = length) { values ->
                 createFuzzedArrayModel(classId, length, values.map { it.model } )
+            }.apply {
+                limit = (totalLimit / lengths.size).coerceAtLeast(1)
             })
         }
     }

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

@@ -15,7 +15,7 @@ import org.utbot.fuzzer.objects.create
 
 class CollectionWithModificationModelProvider(
     idGenerator: IdentityPreservingIdGenerator<Int>,
-    recursionDepthLeft: Int = 1,
+    recursionDepthLeft: Int = 2,
     private var defaultModificationCount: IntArray = intArrayOf(0, 1, 3)
 ) : RecursiveModelProvider(idGenerator, recursionDepthLeft) {
 
@@ -55,7 +55,7 @@ class CollectionWithModificationModelProvider(
     )
     private var modificationCount = 7
 
-    override fun newInstance(parentProvider: RecursiveModelProvider): RecursiveModelProvider {
+    override fun newInstance(parentProvider: RecursiveModelProvider, constructor: ModelConstructor): RecursiveModelProvider {
         val newInstance = CollectionWithModificationModelProvider(
             parentProvider.idGenerator, parentProvider.recursionDepthLeft - 1
         )

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

@@ -34,9 +34,9 @@ import org.utbot.fuzzer.objects.assembleModel
  */
 class ObjectModelProvider(
     idGenerator: IdentityPreservingIdGenerator<Int>,
-    recursionDepthLeft: Int = 1,
+    recursionDepthLeft: Int = 2,
 ) : RecursiveModelProvider(idGenerator, recursionDepthLeft) {
-    override fun newInstance(parentProvider: RecursiveModelProvider): RecursiveModelProvider {
+    override fun newInstance(parentProvider: RecursiveModelProvider, constructor: ModelConstructor): RecursiveModelProvider {
         val newInstance = ObjectModelProvider(parentProvider.idGenerator, parentProvider.recursionDepthLeft - 1)
         newInstance.copySettings(parentProvider)
         newInstance.branchingLimit = 1
@@ -62,9 +62,9 @@ class ObjectModelProvider(
         )
 
         constructors.forEach { constructorId ->
-            yield(ModelConstructor(constructorId.parameters.map { classId -> FuzzedType(classId) }) {
-                assembleModel(idGenerator.createId(), constructorId, it)
-            })
+            // When branching limit = 1 this block tries to create new values
+            // and mutate some fields. Only if there's no option next block
+            // with empty constructor should be used.
             if (constructorId.parameters.isEmpty()) {
                 val fields = findSuitableFields(constructorId.classId, description)
                 if (fields.isNotEmpty()) {
@@ -75,6 +75,9 @@ class ObjectModelProvider(
                     )
                 }
             }
+            yield(ModelConstructor(constructorId.parameters.map { classId -> FuzzedType(classId) }) {
+                assembleModel(idGenerator.createId(), constructorId, it)
+            })
         }
     }
 

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

@@ -54,7 +54,7 @@ abstract class RecursiveModelProvider(
     /**
      * Creates instance of the class on which it is called, assuming that it will be called recursively from [parentProvider]
      */
-    protected abstract fun newInstance(parentProvider: RecursiveModelProvider): RecursiveModelProvider
+    protected abstract fun newInstance(parentProvider: RecursiveModelProvider, constructor: ModelConstructor): RecursiveModelProvider
 
     /**
      * Creates [ModelProvider]s that will be used to generate values recursively. The order of elements in returned list is important:
@@ -101,16 +101,16 @@ abstract class RecursiveModelProvider(
                 neededTypes[index % neededTypes.size] // because we can repeat neededTypes several times
             }
         }
-        return fuzz(syntheticMethodDescription, nextModelProvider())
+        return fuzz(syntheticMethodDescription, nextModelProvider(this))
             .map { createModel(it) }
             .take(limit)
     }
 
-    private fun nextModelProvider(): ModelProvider =
+    private fun nextModelProvider(constructor: ModelConstructor): ModelProvider =
         if (recursionDepthLeft > 0) {
             modelProviderForRecursiveCalls.map {
                 if (it is RecursiveModelProvider) {
-                    it.newInstance(this)
+                    it.newInstance(this, constructor)
                 } else { it }
             }
         } else {

utbot-fuzzers/src/test/kotlin/org/utbot/framework/plugin/api/ModelProviderTest.kt

@@ -389,7 +389,7 @@ class ModelProviderTest {
 
         withUtContext(UtContext(this::class.java.classLoader)) {
             val result = collect(
-                ObjectModelProvider(ReferencePreservingIntIdGenerator(0)),
+                ObjectModelProvider(ReferencePreservingIntIdGenerator(0), recursionDepthLeft = 1),
                 parameters = listOf(MyA::class.java.id)
             )
             assertEquals(1, result.size)
@@ -478,14 +478,14 @@ class ModelProviderTest {
         )
 
         withUtContext(UtContext(this::class.java.classLoader)) {
-            val result = collect(ObjectModelProvider(ReferencePreservingIntIdGenerator(0)).apply {
+            val result = collect(ObjectModelProvider(ReferencePreservingIntIdGenerator(0), recursionDepthLeft = 1).apply {
                 modelProviderForRecursiveCalls = PrimitiveDefaultsModelProvider
             }, parameters = listOf(FieldSetterClass::class.java.id))
             assertEquals(1, result.size)
             assertEquals(2, result[0]!!.size)
-            assertEquals(0, (result[0]!![0] as UtAssembleModel).modificationsChain.size) { "One of models must be without any modifications" }
+            assertEquals(0, (result[0]!![1] as UtAssembleModel).modificationsChain.size) { "One of models must be without any modifications" }
             val expectedModificationSize = 3
-            val modificationsChain = (result[0]!![1] as UtAssembleModel).modificationsChain
+            val modificationsChain = (result[0]!![0] as UtAssembleModel).modificationsChain
             val actualModificationSize = modificationsChain.size
             assertEquals(expectedModificationSize, actualModificationSize) { "In target class there's only $expectedModificationSize fields that can be changed, but generated $actualModificationSize modifications" }
 
@@ -513,10 +513,10 @@ class ModelProviderTest {
             }
             assertEquals(1, result.size)
             assertEquals(3, result[0]!!.size)
-            assertEquals(0, (result[0]!![0] as UtAssembleModel).modificationsChain.size) { "One of models must be without any modifications" }
-            assertEquals(0, (result[0]!![2] as UtAssembleModel).modificationsChain.size) { "Modification by constructor doesn't change fields" }
+            assertEquals(0, (result[0]!![2] as UtAssembleModel).modificationsChain.size) { "One of models must be without any modifications" }
+            assertEquals(0, (result[0]!![1] as UtAssembleModel).modificationsChain.size) { "Modification by constructor doesn't change fields" }
             val expectedModificationSize = 1
-            val modificationsChain = (result[0]!![1] as UtAssembleModel).modificationsChain
+            val modificationsChain = (result[0]!![0] as UtAssembleModel).modificationsChain
             val actualModificationSize = modificationsChain.size
             assertEquals(expectedModificationSize, actualModificationSize) { "In target class there's only $expectedModificationSize fields that can be changed, but generated $actualModificationSize modifications" }