Added constructing this instance for captured values of lambda in case of early return (#1658)

Author: Damtev

utbot-framework-test/src/test/kotlin/org/utbot/examples/lambda/ThrowingWithLambdaExampleTest.kt

@@ -0,0 +1,21 @@
+package org.utbot.examples.lambda
+
+import org.junit.jupiter.api.Test
+import org.utbot.testcheckers.eq
+import org.utbot.testing.DoNotCalculate
+import org.utbot.testing.UtValueTestCaseChecker
+
+class ThrowingWithLambdaExampleTest : UtValueTestCaseChecker(testClass = ThrowingWithLambdaExample::class) {
+    @Test
+    fun testAnyExample() {
+        check(
+            ThrowingWithLambdaExample::anyExample,
+            eq(4),
+            { l, _, _ -> l == null },
+            { l, _, r -> l.isEmpty() && r == false },
+            { l, _, r -> l.isNotEmpty() && 42 in l && r == true },
+            { l, _, r -> l.isNotEmpty() && 42 !in l && r == false },
+            coverage = DoNotCalculate // TODO failed coverage calculation
+        )
+    }
+}

utbot-framework/src/main/kotlin/org/utbot/engine/ObjectCounter.kt

@@ -0,0 +1,12 @@
+package org.utbot.engine
+
+import java.util.concurrent.atomic.AtomicInteger
+
+/**
+ * Counts new objects during execution. Used to give new addresses for objects in [Traverser] and [Resolver].
+ */
+data class ObjectCounter(val initialValue: Int) {
+    private val internalCounter = AtomicInteger(initialValue)
+
+    fun createNewAddr(): Int = internalCounter.getAndIncrement()
+}

utbot-framework/src/main/kotlin/org/utbot/engine/Resolver.kt

@@ -101,6 +101,7 @@ import org.utbot.engine.types.TypeRegistry
 import org.utbot.engine.types.TypeResolver
 import org.utbot.framework.plugin.api.visible.UtStreamConsumingException
 import org.utbot.framework.plugin.api.UtStreamConsumingFailure
+import org.utbot.framework.plugin.api.util.isStatic
 
 // hack
 const val MAX_LIST_SIZE = 10
@@ -130,7 +131,8 @@ class Resolver(
     private val typeResolver: TypeResolver,
     val holder: UtSolverStatusSAT,
     methodUnderTest: ExecutableId,
-    private val softMaxArraySize: Int
+    private val softMaxArraySize: Int,
+    private val objectCounter: ObjectCounter
 ) {
 
     private val classLoader: ClassLoader
@@ -529,7 +531,28 @@ class Resolver(
 
         if (sootClass.isLambda) {
             return constructLambda(concreteAddr, sootClass).also { lambda ->
-                lambda.capturedValues += collectFieldModels(addr, actualType).values
+                val collectedFieldModels = collectFieldModels(addr, actualType).toMutableMap()
+
+                if (!lambda.lambdaMethodId.isStatic) {
+                    val thisInstanceField = FieldId(declaringClass = sootClass.id, name = "cap0")
+
+                    if (thisInstanceField !in collectedFieldModels || collectedFieldModels[thisInstanceField] is UtNullModel) {
+                        // Non-static lambda has to have `this` instance captured as `cap0` field that cannot be null,
+                        // so if we do not have it as field or it is null (for example, an exception was thrown before initializing lambda),
+                        // we need to construct `this` instance by ourselves.
+                        // Since we do not know its fields, we create an empty object of the corresponding type that will be
+                        // constructed in codegen using reflection.
+                        val thisInstanceClassId = sootClass.name.substringBeforeLast("\$lambda").let {
+                            Scene.v().getSootClass(it)
+                        }.id
+                        val thisInstanceModel =
+                            UtCompositeModel(objectCounter.createNewAddr(), thisInstanceClassId, isMock = false)
+
+                        collectedFieldModels[thisInstanceField] = thisInstanceModel
+                    }
+                }
+
+                lambda.capturedValues += collectedFieldModels.values
             }
         }
 

utbot-framework/src/main/kotlin/org/utbot/engine/Traverser.kt

@@ -267,9 +267,10 @@ class Traverser(
 
     private var queuedSymbolicStateUpdates = SymbolicStateUpdate()
 
-    private val objectCounter = AtomicInteger(TypeRegistry.objectCounterInitialValue)
+    internal val objectCounter = ObjectCounter(TypeRegistry.objectCounterInitialValue)
+
     private fun findNewAddr(insideStaticInitializer: Boolean): UtAddrExpression {
-        val newAddr = objectCounter.getAndIncrement()
+        val newAddr = objectCounter.createNewAddr()
         // return negative address for objects created inside static initializer
         // to make their address space be intersected with address space of
         // parameters of method under symbolic execution

utbot-framework/src/main/kotlin/org/utbot/engine/UtBotSymbolicEngine.kt

@@ -237,7 +237,8 @@ class UtBotSymbolicEngine(
                             typeResolver,
                             state.solver.lastStatus as UtSolverStatusSAT,
                             methodUnderTest,
-                            softMaxArraySize
+                            softMaxArraySize,
+                            traverser.objectCounter
                         )
 
                         val resolvedParameters = state.methodUnderTestParameters
@@ -444,8 +445,16 @@ class UtBotSymbolicEngine(
         Predictors.testName.provide(state.path, predictedTestName, "")
 
         // resolving
-        val resolver =
-            Resolver(hierarchy, memory, typeRegistry, typeResolver, holder, methodUnderTest, softMaxArraySize)
+        val resolver = Resolver(
+            hierarchy,
+            memory,
+            typeRegistry,
+            typeResolver,
+            holder,
+            methodUnderTest,
+            softMaxArraySize,
+            traverser.objectCounter
+        )
 
         val (modelsBefore, modelsAfter, instrumentation) = resolver.resolveModels(parameters)
 

utbot-sample/src/main/java/org/utbot/examples/lambda/ThrowingWithLambdaExample.java

@@ -0,0 +1,27 @@
+package org.utbot.examples.lambda;
+
+import org.utbot.api.mock.UtMock;
+
+public class ThrowingWithLambdaExample {
+    // This example mostly checks that we can construct non-static lambda even if it's init section was not analyzed
+    // (e.g., an exception was thrown before it).
+    boolean anyExample(int[] values, IntPredicate predicate) {
+        UtMock.assume(predicate != null);
+
+        for (int value : values) {
+            if (predicate.test(value)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    // To make this lambda non-static, we need to make it use `this` instance.
+    @SuppressWarnings({"unused", "ConstantConditions"})
+    IntPredicate nonStaticIntPredicate = x -> this != null && x == 42;
+
+    interface IntPredicate {
+        boolean test(int value);
+    }
+}