Fix lambdas in concrete

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

@@ -570,12 +570,31 @@ class UtLambdaModel(
     val capturedValues: MutableList<UtModel> = mutableListOf(),
 ) : UtReferenceModel(id, samType) {
 
+    val isFake: Boolean = lambdaName == fakeName
+
     val lambdaMethodId: MethodId
-        get() = declaringClass.jClass
-            .declaredMethods
-            .singleOrNull { it.name == lambdaName }
-            ?.executableId // synthetic lambda methods should not have overloads, so we always expect there to be only one method with the given name
-            ?: error("More than one method with name $lambdaName found in class: ${declaringClass.canonicalName}")
+        get() {
+            if (isFake) {
+                val targetMethod = samType.jClass.declaredMethods.single()
+                return object : MethodId(
+                    declaringClass,
+                    fakeName,
+                    targetMethod.returnType.id,
+                    targetMethod.parameterTypes.map { it.id }
+                ) {
+                    override val modifiers: Int = ModifierFactory.invoke {
+                        public = true
+                        static = true
+                        final = true
+                    }
+                }
+            }
+            return declaringClass.jClass
+                .declaredMethods
+                .singleOrNull { it.name == lambdaName }
+                ?.executableId // synthetic lambda methods should not have overloads, so we always expect there to be only one method with the given name
+                ?: error("More than one method with name $lambdaName found in class: ${declaringClass.canonicalName}")
+        }
 
     override fun toString(): String = "Anonymous function $lambdaName implementing functional interface $declaringClass"
 
@@ -591,6 +610,18 @@ class UtLambdaModel(
     }
 
     override fun hashCode(): Int = id
+
+    companion object {
+        private const val fakeName = "<FAKE>"
+
+        /**
+         * Create a non-existent lambda with fake method.
+         *
+         * That's temporary solution for building lambdas from concrete values.
+         */
+        fun createFake(id: Int, samType: ClassId, declaringClass: ClassId) =
+            UtLambdaModel(id, samType, declaringClass, fakeName)
+    }
 }
 
 /**

utbot-framework/src/main/kotlin/org/utbot/framework/concrete/UtModelConstructor.kt

@@ -35,6 +35,7 @@ import org.utbot.framework.util.valueToClassId
 import java.lang.reflect.Modifier
 import java.util.IdentityHashMap
 import java.util.stream.BaseStream
+import org.utbot.framework.plugin.api.util.utContext
 
 /**
  * Represents common interface for model constructors.
@@ -79,6 +80,21 @@ class UtModelConstructor(
         return objectToModelCache[value]?.let { (it as? UtReferenceModel)?.id } ?: computeUnusedIdAndUpdate()
     }
 
+    private val proxyLambdaSubstring = "$\$Lambda$"
+
+    private fun isProxyLambda(value: Any?): Boolean {
+        if (value == null) {
+            return false
+        }
+        return proxyLambdaSubstring in value::class.java.name
+    }
+
+    private fun constructFakeLambda(value: Any, classId: ClassId): UtLambdaModel {
+        val baseClassName = value::class.java.name.substringBefore(proxyLambdaSubstring)
+        val baseClass = utContext.classLoader.loadClass(baseClassName).id
+        return UtLambdaModel.createFake(handleId(value), classId, baseClass)
+    }
+
     /**
      * Constructs a UtModel from a concrete [value] with a specific [classId]. The result can be a [UtAssembleModel]
      * as well.
@@ -91,6 +107,9 @@ class UtModelConstructor(
                 return model
             }
         }
+        if (isProxyLambda(value)) {
+            return constructFakeLambda(value!!, classId)
+        }
         return when (value) {
             null -> UtNullModel(classId)
             is Unit -> UtVoidModel