support Iterables and Arrays in the ParameterizedExtension

This also includes support for single parameter tests.

Author: LiamClark

junit-jupiter-migration-support/src/main/java/org/junit/jupiter/migrationsupport/parameterized/ParameterizedExtension.java

@@ -37,6 +37,7 @@
 import org.junit.jupiter.api.extension.TestTemplateInvocationContext;
 import org.junit.jupiter.api.extension.TestTemplateInvocationContextProvider;
 import org.junit.platform.commons.meta.API;
+import org.junit.platform.commons.util.CollectionUtils;
 import org.junit.platform.commons.util.ReflectionUtils;
 import org.junit.runners.Parameterized;
 
@@ -243,18 +244,14 @@ private static ParameterResolutionException unMatchedAmountOfParametersException
 			"The amount of parametersFields in the constructor doesn't match those in the provided parametersFields");
 	}
 
-	private static ParameterResolutionException wrongParametersReturnType() {
-		return new ParameterResolutionException("The @Parameters returns the wrong type");
-	}
-
 	@SuppressWarnings("unchecked")
-	private static Collection<Object[]> convertParametersMethodReturnType(Object o) {
-		if (o instanceof Collection) {
-			return (Collection<Object[]>) o;
-		}
-		else {
-			throw wrongParametersReturnType();
-		}
+	private static Collection<Object[]> convertParametersMethodReturnType(Object obj) {
+		return CollectionUtils.toStream(obj).map(o -> {
+			if (o instanceof Object[]) {
+				return (Object[]) o;
+			}
+			return new Object[] { o };
+		}).collect(toList());
 	}
 
 	private static class ParameterWrapper {

junit-jupiter-migration-support/src/test/java/org/junit/jupiter/migrationsupport/parameterized/ParameterizedExtensionTests.java

@@ -49,7 +49,7 @@ void parametrizedWithParameterFieldInjection() {
 	}
 
 	@ExtendWith(ParameterizedExtension.class)
-	protected static class FibonacciTest {
+	private static class FibonacciTest {
 		@Parameters
 		public static Collection<Object[]> data() {
 			return Arrays.asList(
@@ -88,7 +88,7 @@ void paremeterizedWithConstructorInjection() {
 	}
 
 	@ExtendWith(ParameterizedExtension.class)
-	protected static class ParameterizedTestWithConstructor {
+	private static class ParameterizedTestWithConstructor {
 		@Parameters
 		public static Collection<Object[]> data() {
 			return Arrays.asList(
@@ -116,7 +116,7 @@ void unMatchedConstructorArgumentCount() {
 	}
 
 	@ExtendWith(ParameterizedExtension.class)
-	protected static class UnMatchedConstructor {
+	private static class UnMatchedConstructor {
 		@Parameters
 		public static Collection<Object[]> data() {
 			return Arrays.asList(new Object[][] { { 0, 2 } });
@@ -140,7 +140,7 @@ void unMatchedParameterFieldsCount() {
 	}
 
 	@ExtendWith(ParameterizedExtension.class)
-	protected static class WrongParameters {
+	private static class WrongParameters {
 		@Parameterized.Parameter
 		public int a;
 		@Parameterized.Parameter(1)
@@ -168,7 +168,7 @@ void noInjectionMix() {
 	}
 
 	@ExtendWith(ParameterizedExtension.class)
-	protected static class DoubleInjection {
+	private static class DoubleInjection {
 		@Parameterized.Parameter
 		public int a;
 
@@ -220,7 +220,7 @@ void emptyParametersList() {
 	}
 
 	@ExtendWith(ParameterizedExtension.class)
-	protected static class EmptyParameters {
+	private static class EmptyParameters {
 
 		public EmptyParameters() {
 		}
@@ -243,7 +243,7 @@ void duplicatedParameterFieldIndex() {
 	}
 
 	@ExtendWith(ParameterizedExtension.class)
-	protected static class DuplicatedIndex {
+	private static class DuplicatedIndex {
 		@Parameterized.Parameter
 		public int a;
 
@@ -268,7 +268,7 @@ void parametersAreOnlyCalledOnce() {
 	}
 
 	@ExtendWith(ParameterizedExtension.class)
-	protected static class ParametersCalledOnce {
+	private static class ParametersCalledOnce {
 		private static int invocationCount = 0;
 
 		public ParametersCalledOnce(int a) {
@@ -294,7 +294,7 @@ void multipleTestTemplatesShouldBeRun() {
 	}
 
 	@ExtendWith(ParameterizedExtension.class)
-	static class MultipleTestTemplates {
+	private static class MultipleTestTemplates {
 		private static int invocationCount = 0;
 
 		public MultipleTestTemplates(int a) {
@@ -319,6 +319,30 @@ void secondTemplate() {
 		}
 	}
 
+	@Test
+	void singleParameterIterable() {
+		ExecutionEventRecorder eventRecorder = executeTestsForClass(IterableTest.class);
+		assertThat(eventRecorder.getTestSuccessfulCount()).isEqualTo(2);
+	}
+
+	@ExtendWith(ParameterizedExtension.class)
+	private static class IterableTest {
+
+		public IterableTest(Object o) {
+
+		}
+
+		@Parameters
+		public static Object[] data() {
+			return new Object[] { new Object(), new Object() };
+		}
+
+		@TestTemplate
+		void dummy() {
+
+		}
+	}
+
 	private ExecutionEventRecorder executeTestsForClass(Class<?> testClass) {
 		LauncherDiscoveryRequest request = request().selectors(selectClass(testClass)).build();
 		JupiterTestEngine engine = new JupiterTestEngine();