Using reflection to get the arguments of a JUnit 5 ParameterizedTest. F…

…ixes #372

jgiven-core/src/main/java/com/tngtech/jgiven/impl/util/ReflectionUtil.java

@@ -213,6 +213,17 @@ public Object apply( Field field ) {
         };
     }
 
+    public static Object getFieldValueOrNull(String fieldName, Object target, String errorDescription) {
+        try {
+            Field field = target.getClass().getDeclaredField(fieldName);
+            return getFieldValueOrNull(field, target, errorDescription);
+        } catch (Exception e) {
+            log.warn(
+                    format( "Not able to access field '%s'." + errorDescription, fieldName ), e );
+            return null;
+        }
+    }
+
     public static Object getFieldValueOrNull(Field field, Object target, String errorDescription) {
         makeAccessible( field, "" );
         try {

jgiven-junit5/build.gradle

@@ -22,9 +22,10 @@ test {
 dependencies {
     compile project(':jgiven-core')
 
-    compileOnly 'org.junit.jupiter:junit-jupiter-api:5.2.0'
+    compileOnly 'org.junit.jupiter:junit-jupiter-api:5.3.1'
 
     testCompile project(':jgiven-html5-report')
-    testCompile 'org.junit.jupiter:junit-jupiter-engine:5.2.0'
-    testCompile 'org.junit.platform:junit-platform-runner:1.2.0'
+    testCompile 'org.junit.jupiter:junit-jupiter-engine:5.3.1'
+    testCompile 'org.junit.platform:junit-platform-runner:1.3.1'
+    testCompile 'org.junit.jupiter:junit-jupiter-params:5.3.1'
 }

jgiven-junit5/src/main/java/com/tngtech/jgiven/junit5/ArgumentReflectionUtil.java

@@ -0,0 +1,55 @@
+package com.tngtech.jgiven.junit5;
+
+import java.lang.reflect.Field;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.jupiter.api.extension.ExtensionContext;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.tngtech.jgiven.impl.util.ParameterNameUtil;
+import com.tngtech.jgiven.impl.util.ReflectionUtil;
+import com.tngtech.jgiven.report.model.NamedArgument;
+
+class ArgumentReflectionUtil {
+    private static final Logger log = LoggerFactory.getLogger( ArgumentReflectionUtil.class );
+
+    static final String METHOD_EXTENSION_CONTEXT = "org.junit.jupiter.engine.descriptor.MethodExtensionContext";
+    static final String TEST_TEMPLATE_INVOCATION_TEST_DESCRIPTOR = "org.junit.jupiter.engine.descriptor.TestTemplateInvocationTestDescriptor";
+    static final String PARAMETERIZED_TEST_INVOCATION_CONTEXT = "org.junit.jupiter.params.ParameterizedTestInvocationContext";
+
+    static final String ERROR = "Not able to access field containing test method arguments. " +
+            "Probably the internal representation has changed. Consider writing a bug report.";
+
+    /**
+     * This is a very ugly workaround to get the method arguments from the JUnit 5 context via reflection.
+     */
+    static List<NamedArgument> getNamedArgs( ExtensionContext context ) {
+        List<NamedArgument> namedArgs = new ArrayList<>();
+
+        if( context.getTestMethod().get().getParameterCount() > 0 ) {
+            try {
+                if( context.getClass().getCanonicalName().equals( METHOD_EXTENSION_CONTEXT ) ) {
+                    Field field = context.getClass().getSuperclass().getDeclaredField( "testDescriptor" );
+                    Object testDescriptor = ReflectionUtil.getFieldValueOrNull( field, context, ERROR );
+                    if( testDescriptor != null
+                            && testDescriptor.getClass().getCanonicalName().equals( TEST_TEMPLATE_INVOCATION_TEST_DESCRIPTOR ) ) {
+                        Object invocationContext = ReflectionUtil.getFieldValueOrNull( "invocationContext", testDescriptor, ERROR );
+                        if( invocationContext != null
+                                && invocationContext.getClass().getCanonicalName().equals( PARAMETERIZED_TEST_INVOCATION_CONTEXT ) ) {
+                            Object arguments = ReflectionUtil.getFieldValueOrNull( "arguments", invocationContext, ERROR );
+                            List<Object> args = Arrays.asList( (Object[]) arguments );
+                            namedArgs = ParameterNameUtil.mapArgumentsWithParameterNames( context.getTestMethod().get(), args );
+                        }
+                    }
+                }
+            } catch( Exception e ) {
+                log.warn( ERROR, e );
+            }
+        }
+
+        return namedArgs;
+    }
+}

jgiven-junit5/src/main/java/com/tngtech/jgiven/junit5/JGivenExtension.java

@@ -3,9 +3,7 @@
 import static com.tngtech.jgiven.report.model.ExecutionStatus.FAILED;
 import static com.tngtech.jgiven.report.model.ExecutionStatus.SUCCESS;
 
-import java.util.ArrayList;
 import java.util.EnumSet;
-import java.util.List;
 
 import org.junit.jupiter.api.Assumptions;
 import org.junit.jupiter.api.Tag;
@@ -17,7 +15,6 @@
 import com.tngtech.jgiven.impl.ScenarioBase;
 import com.tngtech.jgiven.impl.ScenarioHolder;
 import com.tngtech.jgiven.report.impl.CommonReportHelper;
-import com.tngtech.jgiven.report.model.NamedArgument;
 import com.tngtech.jgiven.report.model.ReportModel;
 
 /**
@@ -70,9 +67,8 @@ public void afterAll( ExtensionContext context ) throws Exception {
 
     @Override
     public void beforeEach( ExtensionContext context ) throws Exception {
-        List<NamedArgument> args = new ArrayList<NamedArgument>();
-        getScenario().startScenario( context.getTestClass().get(), context.getTestMethod().get(), args );
-
+        getScenario().startScenario( context.getTestClass().get(), context.getTestMethod().get(),
+            ArgumentReflectionUtil.getNamedArgs(context) );
     }
 
     @Override
@@ -119,4 +115,5 @@ public void postProcessTestInstance( Object testInstance, ExtensionContext conte
         scenario.getExecutor().injectStages( testInstance );
         scenario.getExecutor().readScenarioState( testInstance );
     }
+
 }

jgiven-junit5/src/test/java/com/tngtech/jgiven/junit5/test/ParameterizedTestTest.java

@@ -0,0 +1,27 @@
+package com.tngtech.jgiven.junit5.test;
+
+import static org.assertj.core.api.Java6Assertions.assertThat;
+
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import com.tngtech.jgiven.annotation.CaseAs;
+import com.tngtech.jgiven.junit5.JGivenExtension;
+import com.tngtech.jgiven.junit5.ScenarioTest;
+
+@ExtendWith( JGivenExtension.class )
+public class ParameterizedTestTest extends ScenarioTest<GivenStage, WhenStage, ThenStage> {
+
+    @ParameterizedTest( name = "{index} [{arguments}] param name" )
+    @ValueSource( strings = { "Hello", "World" } )
+    @CaseAs( "Case $1" )
+    public void parameterized_scenario( String param ) {
+        given().some_state();
+        when().some_action_with_a_parameter( param );
+        then().some_outcome();
+
+        assertThat( getScenario().getScenarioCaseModel().getDescription() ).isIn( "Case Hello", "Case World" );
+    }
+
+}

jgiven-junit5/src/test/java/com/tngtech/jgiven/junit5/test/WhenStage.java

@@ -17,6 +17,10 @@ void some_action() {
         someResult = "Some Result";
     }
 
+    void some_action_with_a_parameter(String s) {
+        someResult = "s";
+    }
+
     public WhenStage some_failing_step() {
         Assertions.assertTrue(false, "Intentionally failing");
         return this;