Very simple UtAssembleModel improver (#2678)

* Very simple UtAssembleModel improver

* Use `IdentityHashMap`-based cache when mapping `UtModel`s

* Improve checks for `UtAssembleModel`s created with `createInstance` method

---------

Co-authored-by: IlyaMuravjov <muravjovilya@gmail.com>

Author: EgorkaKulikov

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

@@ -1,11 +1,12 @@
 package org.utbot.framework.plugin.api.mapper
 
 import org.utbot.framework.plugin.api.UtModel
+import java.util.IdentityHashMap
 
 class UtModelSafeCastingCachingShallowMapper(
     val mapper: (UtModel) -> UtModel
 ) : UtModelMapper {
-    private val cache = mutableMapOf<UtModel, UtModel>()
+    private val cache = IdentityHashMap<UtModel, UtModel>()
 
     override fun <T : UtModel> map(model: T, clazz: Class<T>): T {
         val mapped = cache.getOrPut(model) { mapper(model) }

utbot-junit-contest/src/main/kotlin/org/utbot/contest/usvm/JcToUtExecutionConverter.kt

@@ -17,19 +17,27 @@ import org.usvm.instrumentation.testcase.descriptor.Descriptor2ValueConverter
 import org.usvm.instrumentation.testcase.descriptor.UTestExceptionDescriptor
 import org.usvm.instrumentation.util.enclosingClass
 import org.usvm.instrumentation.util.enclosingMethod
+import org.utbot.common.isPublic
 import org.utbot.contest.usvm.executor.JcExecution
 import org.utbot.framework.codegen.domain.builtin.UtilMethodProvider
+import org.utbot.framework.plugin.api.ClassId
 import org.utbot.framework.plugin.api.Coverage
 import org.utbot.framework.plugin.api.EnvironmentModels
 import org.utbot.framework.plugin.api.ExecutableId
 import org.utbot.framework.plugin.api.Instruction
+import org.utbot.framework.plugin.api.UtAssembleModel
+import org.utbot.framework.plugin.api.UtExecutableCallModel
 import org.utbot.framework.plugin.api.UtExecution
 import org.utbot.framework.plugin.api.UtExecutionFailure
 import org.utbot.framework.plugin.api.UtExecutionSuccess
 import org.utbot.framework.plugin.api.UtExplicitlyThrownException
 import org.utbot.framework.plugin.api.UtImplicitlyThrownException
 import org.utbot.framework.plugin.api.UtInstrumentation
+import org.utbot.framework.plugin.api.UtPrimitiveModel
 import org.utbot.framework.plugin.api.UtVoidModel
+import org.utbot.framework.plugin.api.mapper.UtModelDeepMapper
+import org.utbot.framework.plugin.api.util.executableId
+import org.utbot.framework.plugin.api.util.jClass
 import org.utbot.framework.plugin.api.util.utContext
 import org.utbot.fuzzer.IdGenerator
 
@@ -40,7 +48,7 @@ class JcToUtExecutionConverter(
     private val jcClasspath: JcClasspath,
     private val idGenerator: IdGenerator<Int>,
     private val instructionIdProvider: InstructionIdProvider,
-    utilMethodProvider: UtilMethodProvider,
+    private val utilMethodProvider: UtilMethodProvider,
 ) {
     private val toValueConverter = Descriptor2ValueConverter(utContext.classLoader)
 
@@ -100,7 +108,41 @@ class JcToUtExecutionConverter(
             }
         } ?: return null
 
-        return utUsvmExecution
+        return utUsvmExecution.mapModels(constructAssemblingMapper())
+    }
+
+    private fun constructAssemblingMapper(): UtModelDeepMapper = UtModelDeepMapper { model ->
+        // TODO usvm-sbft: support constructors with parameters here if it is really required
+        // Unfortunately, it is not possible to use [AssembleModelGeneral] as it requires soot being initialized.
+        if (model !is UtAssembleModel
+            || utilMethodProvider.createInstanceMethodId != model.instantiationCall.statement
+            || model.modificationsChain.isNotEmpty()) {
+            return@UtModelDeepMapper model
+        }
+
+        val instantiatingClassName = (model
+            .instantiationCall
+            .params
+            .single() as UtPrimitiveModel).value.toString()
+
+        val defaultConstructor = ClassId(instantiatingClassName)
+            .jClass
+            .constructors
+            .firstOrNull { it.isPublic && it.parameters.isEmpty() }
+
+
+        defaultConstructor?.let { ctor ->
+            UtAssembleModel(
+                id = idGenerator.createId(),
+                classId = model.classId,
+                modelName = "",
+                instantiationCall = UtExecutableCallModel(
+                    instance = null,
+                    executable = ctor.executableId,
+                    params = emptyList(),
+                )
+            )
+        } ?: model
     }
 
     private fun convertException(exceptionDescriptor: UTestExceptionDescriptor): Throwable =