Improve detection of NPEs caused by this instance fields being null in Spring unit tests

utbot-framework-api/src/main/kotlin/org/utbot/framework/TrustedPackages.kt

@@ -1,5 +1,6 @@
 package org.utbot.framework
 
+import org.utbot.framework.plugin.api.ClassId
 import soot.SootClass
 
 /**
@@ -10,7 +11,17 @@ private val isPackageTrusted: MutableMap<String, Boolean> = mutableMapOf()
 /**
  * Determines whether [this] class is from trusted libraries as defined in [TrustedLibraries].
  */
-fun SootClass.isFromTrustedLibrary(): Boolean {
+fun SootClass.isFromTrustedLibrary(): Boolean = isFromTrustedLibrary(packageName)
+
+/**
+ * Determines whether [this] class is from trusted libraries as defined in [TrustedLibraries].
+ */
+fun ClassId.isFromTrustedLibrary(): Boolean = isFromTrustedLibrary(packageName)
+
+/**
+ * Determines whether [packageName] is from trusted libraries as defined in [TrustedLibraries].
+ */
+fun isFromTrustedLibrary(packageName: String): Boolean {
     isPackageTrusted[packageName]?.let {
         return it
     }

utbot-framework-api/src/main/kotlin/org/utbot/framework/plugin/api/util/IdUtil.kt

@@ -468,6 +468,13 @@ val ClassId.allDeclaredFieldIds: Sequence<FieldId>
 val SootField.fieldId: FieldId
     get() = FieldId(declaringClass.id, name)
 
+/**
+ * For some lambdas class names in byte code and in Soot don't match, so we may fail
+ * to convert some soot fields to Java fields, in such case `null` is returned.
+ */
+val SootField.jFieldOrNull: Field?
+    get() = runCatching { fieldId.jField }.getOrNull()
+
 // FieldId utils
 val FieldId.safeJField: Field?
     get() = declaringClass.jClass.declaredFields.firstOrNull { it.name == name }

utbot-framework-api/src/main/kotlin/org/utbot/framework/plugin/api/util/SpringModelUtils.kt

@@ -22,6 +22,11 @@ private val logger = KotlinLogging.logger {}
 
 object SpringModelUtils {
     val autowiredClassId = ClassId("org.springframework.beans.factory.annotation.Autowired")
+    val injectClassIds = getClassIdFromEachAvailablePackage(
+        packages = listOf("javax", "jakarta"),
+        classNameFromPackage = "inject.Inject"
+    )
+    val componentClassId = ClassId("org.springframework.stereotype.Component")
 
     val applicationContextClassId = ClassId("org.springframework.context.ApplicationContext")
     val repositoryClassId = ClassId("org.springframework.data.repository.Repository")

utbot-framework/src/main/kotlin/org/utbot/framework/assemble/AssembleModelGenerator.kt

@@ -8,8 +8,8 @@ import org.utbot.engine.ResolvedModels
 import org.utbot.framework.UtSettings
 import org.utbot.framework.codegen.util.isAccessibleFrom
 import org.utbot.modifications.AnalysisMode.SettersAndDirectAccessors
-import org.utbot.modifications.ConstructorAnalyzer
-import org.utbot.modifications.ConstructorAssembleInfo
+import org.utbot.modifications.ExecutableAnalyzer
+import org.utbot.modifications.ExecutableAssembleInfo
 import org.utbot.modifications.UtBotFieldsModificatorsSearcher
 import org.utbot.framework.plugin.api.ClassId
 import org.utbot.framework.plugin.api.ConstructorId
@@ -77,7 +77,7 @@ class AssembleModelGenerator(private val basePackageName: String) {
         UtBotFieldsModificatorsSearcher(
             fieldInvolvementMode = FieldInvolvementMode.WriteOnly
         )
-    private val constructorAnalyzer = ConstructorAnalyzer()
+    private val executableAnalyzer = ExecutableAnalyzer()
 
     /**
      * Clears state before and after block execution.
@@ -284,8 +284,8 @@ class AssembleModelGenerator(private val basePackageName: String) {
             modelsInAnalysis.add(compositeModel)
 
             val constructorInfo =
-                if (shouldAnalyzeConstructor) constructorAnalyzer.analyze(constructorId)
-                else ConstructorAssembleInfo(constructorId)
+                if (shouldAnalyzeConstructor) executableAnalyzer.analyze(constructorId)
+                else ExecutableAssembleInfo(constructorId)
 
             val instantiationCall = constructorCall(compositeModel, constructorInfo)
             return UtAssembleModel(
@@ -406,9 +406,9 @@ class AssembleModelGenerator(private val basePackageName: String) {
      */
     private fun constructorCall(
         compositeModel: UtCompositeModel,
-        constructorInfo: ConstructorAssembleInfo,
+        constructorInfo: ExecutableAssembleInfo,
     ): UtExecutableCallModel {
-        val constructorParams = constructorInfo.constructorId.parameters.withIndex()
+        val constructorParams = constructorInfo.executableId.parameters.withIndex()
             .map { (index, param) ->
                 val modelOrNull = compositeModel.fields
                     .filter { it.key == constructorInfo.params[index] }
@@ -418,7 +418,7 @@ class AssembleModelGenerator(private val basePackageName: String) {
                 assembleModel(fieldModel)
             }
 
-        return UtExecutableCallModel(instance = null, constructorInfo.constructorId, constructorParams)
+        return UtExecutableCallModel(instance = null, constructorInfo.executableId, constructorParams)
     }
 
     /**
@@ -445,11 +445,11 @@ class AssembleModelGenerator(private val basePackageName: String) {
             val fromUtilPackage = classId.packageName.startsWith("java.util")
             constructorIds
                 .sortedBy { it.parameters.size }
-                .firstOrNull { it.parameters.isEmpty() && fromUtilPackage || constructorAnalyzer.isAppropriate(it) }
+                .firstOrNull { it.parameters.isEmpty() && fromUtilPackage || executableAnalyzer.isAppropriate(it) }
         } else {
             constructorIds
                 .sortedByDescending { it.parameters.size }
-                .firstOrNull { constructorAnalyzer.isAppropriate(it) }
+                .firstOrNull { executableAnalyzer.isAppropriate(it) }
         }
     }
 

utbot-framework/src/main/kotlin/org/utbot/framework/context/NonNullSpeculator.kt

@@ -1,17 +1,28 @@
 package org.utbot.framework.context
 
 import org.utbot.framework.plugin.api.ClassId
+import org.utbot.framework.plugin.api.FieldId
 import soot.SootField
 
+/**
+ * Checks whether accessing [field] (with a method invocation or field access) speculatively
+ * cannot produce [NullPointerException] (according to its finality or accessibility).
+ *
+ * @see docs/SpeculativeFieldNonNullability.md for more information.
+ *
+ * NOTE: methods for both [FieldId] and [SootField] are provided, because for some lambdas
+ * class names in byte code and in Soot do not match, making conversion between two field
+ * representations not always possible, which in turn makes us to support both [FieldId]
+ * and [SootField] to be useful for both fuzzer and symbolic engine respectively.
+ */
 interface NonNullSpeculator {
-    /**
-     * Checks whether accessing [field] (with a method invocation or field access) speculatively
-     * cannot produce [NullPointerException] (according to its finality or accessibility).
-     *
-     * @see docs/SpeculativeFieldNonNullability.md for more information.
-     */
     fun speculativelyCannotProduceNullPointerException(
         field: SootField,
         classUnderTest: ClassId,
     ): Boolean
+
+    fun speculativelyCannotProduceNullPointerException(
+        field: FieldId,
+        classUnderTest: ClassId,
+    ): Boolean
 }

utbot-framework/src/main/kotlin/org/utbot/framework/context/simple/SimpleNonNullSpeculator.kt

@@ -4,6 +4,9 @@ import org.utbot.framework.UtSettings
 import org.utbot.framework.context.NonNullSpeculator
 import org.utbot.framework.isFromTrustedLibrary
 import org.utbot.framework.plugin.api.ClassId
+import org.utbot.framework.plugin.api.FieldId
+import org.utbot.framework.plugin.api.util.isFinal
+import org.utbot.framework.plugin.api.util.isPublic
 import soot.SootField
 
 class SimpleNonNullSpeculator : NonNullSpeculator {
@@ -14,4 +17,12 @@ class SimpleNonNullSpeculator : NonNullSpeculator {
         !UtSettings.maximizeCoverageUsingReflection &&
                 field.declaringClass.isFromTrustedLibrary() &&
                 (field.isFinal || !field.isPublic)
+
+    override fun speculativelyCannotProduceNullPointerException(
+        field: FieldId,
+        classUnderTest: ClassId
+    ): Boolean =
+        !UtSettings.maximizeCoverageUsingReflection &&
+                field.declaringClass.isFromTrustedLibrary() &&
+                (field.isFinal || !field.isPublic)
 }

utbot-framework/src/main/kotlin/org/utbot/framework/context/utils/ApplicationContextUtils.kt

@@ -2,6 +2,7 @@ package org.utbot.framework.context.utils
 
 import org.utbot.framework.context.ApplicationContext
 import org.utbot.framework.context.ConcreteExecutionContext
+import org.utbot.framework.context.ConcreteExecutionContext.FuzzingContextParams
 import org.utbot.fuzzing.JavaValueProvider
 
 fun ApplicationContext.transformConcreteExecutionContext(
@@ -18,5 +19,5 @@ fun ApplicationContext.transformConcreteExecutionContext(
 }
 
 fun ApplicationContext.transformValueProvider(
-    transformer: (JavaValueProvider) -> JavaValueProvider
+    transformer: FuzzingContextParams.(JavaValueProvider) -> JavaValueProvider
 ) = transformConcreteExecutionContext { it.transformValueProvider(transformer) }

utbot-framework/src/main/kotlin/org/utbot/framework/context/utils/ConcreteExecutionContextUtils.kt

@@ -4,6 +4,14 @@ import org.utbot.framework.context.ConcreteExecutionContext
 import org.utbot.framework.context.ConcreteExecutionContext.FuzzingContextParams
 import org.utbot.framework.context.JavaFuzzingContext
 import org.utbot.fuzzing.JavaValueProvider
+import org.utbot.instrumentation.instrumentation.execution.UtExecutionInstrumentation
+
+fun ConcreteExecutionContext.transformInstrumentationFactory(
+    transformer: (UtExecutionInstrumentation.Factory<*>) -> UtExecutionInstrumentation.Factory<*>
+) = object : ConcreteExecutionContext by this {
+    override val instrumentationFactory: UtExecutionInstrumentation.Factory<*> =
+        transformer(this@transformInstrumentationFactory.instrumentationFactory)
+}
 
 fun ConcreteExecutionContext.transformJavaFuzzingContext(
     transformer: FuzzingContextParams.(JavaFuzzingContext) -> JavaFuzzingContext
@@ -14,5 +22,7 @@ fun ConcreteExecutionContext.transformJavaFuzzingContext(
 }
 
 fun ConcreteExecutionContext.transformValueProvider(
-    transformer: (JavaValueProvider) -> JavaValueProvider
-) = transformJavaFuzzingContext { it.transformValueProvider(transformer) }
+    transformer: FuzzingContextParams.(JavaValueProvider) -> JavaValueProvider
+) = transformJavaFuzzingContext { javaFuzzingContext ->
+    javaFuzzingContext.transformValueProvider { valueProvider -> transformer(valueProvider) }
+}

utbot-java-fuzzing/src/main/kotlin/org/utbot/fuzzing/spring/JavaLangObject.kt

@@ -0,0 +1,35 @@
+package org.utbot.fuzzing.spring
+
+import org.utbot.framework.plugin.api.ClassId
+import org.utbot.framework.plugin.api.util.jClass
+import org.utbot.framework.plugin.api.util.objectClassId
+import org.utbot.fuzzer.FuzzedType
+import org.utbot.fuzzer.FuzzedValue
+import org.utbot.fuzzer.toTypeParametrizedByTypeVariables
+import org.utbot.fuzzing.FuzzedDescription
+import org.utbot.fuzzing.JavaValueProvider
+import org.utbot.fuzzing.Routine
+import org.utbot.fuzzing.Seed
+import org.utbot.fuzzing.providers.nullRoutine
+import org.utbot.fuzzing.toFuzzerType
+
+class JavaLangObjectValueProvider(
+    private val classesToTryUsingAsJavaLangObject: List<ClassId>,
+) : JavaValueProvider {
+    override fun accept(type: FuzzedType): Boolean {
+        return type.classId == objectClassId
+    }
+
+    override fun generate(description: FuzzedDescription, type: FuzzedType): Sequence<Seed<FuzzedType, FuzzedValue>> =
+        classesToTryUsingAsJavaLangObject.map { classToUseAsObject ->
+            val fuzzedType = toFuzzerType(
+                type = classToUseAsObject.jClass.toTypeParametrizedByTypeVariables(),
+                cache = description.typeCache
+            )
+            Seed.Recursive(
+                construct = Routine.Create(listOf(fuzzedType)) { (value) -> value },
+                modify = emptySequence(),
+                empty = nullRoutine(type.classId)
+            )
+        }.asSequence()
+}

utbot-java-fuzzing/src/main/kotlin/org/utbot/fuzzing/spring/unit/InjectMocks.kt

@@ -1,6 +1,7 @@
 package org.utbot.fuzzing.spring.unit
 
 import org.utbot.framework.plugin.api.ClassId
+import org.utbot.framework.plugin.api.FieldId
 import org.utbot.framework.plugin.api.UtCompositeModel
 import org.utbot.framework.plugin.api.util.allDeclaredFieldIds
 import org.utbot.framework.plugin.api.util.isFinal
@@ -30,7 +31,8 @@ val INJECT_MOCK_FLAG = ScopeProperty<Unit>(
  */
 class InjectMockValueProvider(
     private val idGenerator: IdGenerator<Int>,
-    private val classUnderTest: ClassId
+    private val classUnderTest: ClassId,
+    private val isFieldNonNull: (FieldId) -> Boolean
 ) : JavaValueProvider {
     override fun enrich(description: FuzzedDescription, type: FuzzedType, scope: Scope) {
         if (description.description.isStatic == false && scope.parameterIndex == 0 && scope.recursionDepth == 1) {
@@ -43,14 +45,24 @@ class InjectMockValueProvider(
     override fun generate(description: FuzzedDescription, type: FuzzedType): Sequence<Seed<FuzzedType, FuzzedValue>> {
         if (description.scope?.getProperty(INJECT_MOCK_FLAG) == null) return emptySequence()
         val fields = type.classId.allDeclaredFieldIds.filterNot { it.isStatic && it.isFinal }.toList()
+        val (nonNullFields, nullableFields) = fields.partition(isFieldNonNull)
         return sequenceOf(Seed.Recursive(
-            construct = Routine.Create(types = fields.map { toFuzzerType(it.jField.genericType, description.typeCache) }) { values ->
+            construct = Routine.Create(
+                types = nonNullFields.map { toFuzzerType(it.jField.genericType, description.typeCache) }
+            ) { values ->
                 emptyFuzzedValue(type.classId).also {
                     (it.model as UtCompositeModel).fields.putAll(
-                        fields.zip(values).associate { (field, value) -> field to value.model }
+                        nonNullFields.zip(values).associate { (field, value) -> field to value.model }
                     )
                 }
             },
+            modify = nullableFields.map { field ->
+                Routine.Call<FuzzedType, FuzzedValue>(
+                    types = listOf(toFuzzerType(field.jField.genericType, description.typeCache))
+                ) { instance, (value) ->
+                    (instance.model as UtCompositeModel).fields[field] = value.model
+                }
+            }.asSequence(),
             empty = Routine.Empty { emptyFuzzedValue(type.classId) }
         ))
     }