Make UtExecution abstract, introduce UtFailedExecution as its child (#804)

Make `UtExecution` abstract, introduce `UtFailedExecution` as its child

Author: dtim

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

@@ -144,7 +144,7 @@ sealed class UtResult
  * - coverage information (instructions) if this execution was obtained from the concrete execution.
  * - comments, method names and display names created by utbot-summary module.
  */
-open class UtExecution(
+abstract class UtExecution(
     val stateBefore: EnvironmentModels,
     val stateAfter: EnvironmentModels,
     val result: UtExecutionResult,
@@ -224,6 +224,27 @@ class UtSymbolicExecution(
     }
 }
 
+/**
+ * Execution that result in an error (e.g., JVM crash or another concrete execution error).
+ *
+ * Contains:
+ * - state before the execution;
+ * - result (a [UtExecutionFailure] or its subclass);
+ * - coverage information (instructions) if this execution was obtained from the concrete execution.
+ * - comments, method names and display names created by utbot-summary module.
+ *
+ * This execution does not contain any "after" state, as it is generally impossible to obtain
+ * in case of failure. [MissingState] is used instead.
+ */
+class UtFailedExecution(
+    stateBefore: EnvironmentModels,
+    result: UtExecutionFailure,
+    coverage: Coverage? = null,
+    summary: List<DocStatement>? = null,
+    testMethodName: String? = null,
+    displayName: String? = null
+) : UtExecution(stateBefore, MissingState, result, coverage, summary, testMethodName, displayName)
+
 open class EnvironmentModels(
     val thisInstance: UtModel?,
     val parameters: List<UtModel>,

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

@@ -68,6 +68,7 @@ import org.utbot.framework.plugin.api.UtAssembleModel
 import org.utbot.framework.plugin.api.UtConcreteExecutionFailure
 import org.utbot.framework.plugin.api.UtError
 import org.utbot.framework.plugin.api.UtExecution
+import org.utbot.framework.plugin.api.UtFailedExecution
 import org.utbot.framework.plugin.api.UtInstrumentation
 import org.utbot.framework.plugin.api.UtMethod
 import org.utbot.framework.plugin.api.UtNullModel
@@ -518,9 +519,8 @@ class UtBotSymbolicEngine(
         stateBefore: EnvironmentModels,
         e: ConcreteExecutionFailureException
     ) {
-        val failedConcreteExecution = UtExecution(
+        val failedConcreteExecution = UtFailedExecution(
             stateBefore = stateBefore,
-            stateAfter = MissingState,
             result = UtConcreteExecutionFailure(e)
         )