Assert nullable executions in parametrized tests with special approach (#290)

Author: EgorkaKulikov

utbot-framework/src/main/kotlin/org/utbot/framework/codegen/model/constructor/tree/CgMethodConstructor.kt

@@ -7,6 +7,7 @@ import org.utbot.framework.codegen.ForceStaticMocking
 import org.utbot.framework.codegen.JUNIT5_PARAMETERIZED_PACKAGE
 import org.utbot.framework.codegen.Junit4
 import org.utbot.framework.codegen.Junit5
+import org.utbot.framework.codegen.ParametrizedTestSource
 import org.utbot.framework.codegen.RuntimeExceptionTestsBehaviour.PASS
 import org.utbot.framework.codegen.TestNg
 import org.utbot.framework.codegen.model.constructor.builtin.closeMethodIdOrNull
@@ -996,7 +997,7 @@ internal class CgMethodConstructor(val context: CgContext) : CgContextOwner by c
                                         "but `${resultModel::class}` found"
                             }
 
-                            generateDeepEqualsAssertion(expected, actual)
+                            generateDeepEqualsOrNullAssertion(expected, actual)
                         }
                     }
                 }
@@ -1028,16 +1029,41 @@ internal class CgMethodConstructor(val context: CgContext) : CgContextOwner by c
                         return
                     }
 
-                    generateDeepEqualsAssertion(expected, actual)
+                    generateDeepEqualsOrNullAssertion(expected, actual)
                 }
             }
         }
     }
 
-    private fun generateDeepEqualsAssertion(
+    /**
+     * We can't use standard deepEquals method in parametrized tests
+     * because nullable objects require different asserts.
+     * See https://github.com/UnitTestBot/UTBotJava/issues/252 for more details.
+     */
+    private fun generateDeepEqualsOrNullAssertion(
         expected: CgValue,
-        actual: CgVariable
+        actual: CgVariable,
     ) {
+        when (parameterizedTestSource) {
+            ParametrizedTestSource.DO_NOT_PARAMETRIZE ->
+                currentBlock = currentBlock.addAll(generateDeepEqualsAssertion(expected, actual))
+            ParametrizedTestSource.PARAMETRIZE -> {
+                val assertNullStmt = listOf(testFrameworkManager.assertions[testFramework.assertNull](actual).toStatement())
+                currentBlock = currentBlock.add(
+                    CgIfStatement(
+                        CgEqualTo(expected, nullLiteral()),
+                        assertNullStmt,
+                        generateDeepEqualsAssertion(expected, actual)
+                    )
+                )
+            }
+        }
+    }
+
+    private fun generateDeepEqualsAssertion(
+        expected: CgValue,
+        actual: CgVariable,
+    ): List<CgStatement> {
         require(expected is CgVariable) {
             "Expected value have to be Literal or Variable but `${expected::class}` found"
         }
@@ -1051,7 +1077,8 @@ internal class CgMethodConstructor(val context: CgContext) : CgContextOwner by c
             depth = 0,
             visitedModels = hashSetOf()
         )
-        currentBlock = currentBlock.addAll(statements.dropLastWhile { it is CgEmptyLine })
+
+        return statements.dropLastWhile { it is CgEmptyLine }
     }
 
     private fun recordActualResult() {
@@ -1166,7 +1193,9 @@ internal class CgMethodConstructor(val context: CgContext) : CgContextOwner by c
         }
 
         //TODO: orientation on arbitrary execution may be misleading, but what is the alternative?
-        val arbitraryExecution = utTestCase.executions.firstOrNull { it.result is UtExecutionSuccess }
+        //may be a heuristic to select a model with minimal number of internal nulls should be used
+        val arbitraryExecution = utTestCase.executions
+            .firstOrNull { it.result is UtExecutionSuccess && (it.result as UtExecutionSuccess).model !is UtNullModel }
             ?: utTestCase.executions.first()
 
         return withTestMethodScope(arbitraryExecution) {
@@ -1217,7 +1246,6 @@ internal class CgMethodConstructor(val context: CgContext) : CgContextOwner by c
                 //record result and generate result assertions
                 recordActualResult()
                 generateAssertionsForParameterizedTest()
-
             }
 
             methodType = PARAMETRIZED