Support more return types for the @Parameters method. Fixes #700.

src/main/java/org/junit/runners/Parameterized.java

@@ -8,6 +8,7 @@
 import java.lang.reflect.Field;
 import java.text.MessageFormat;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 
@@ -98,6 +99,37 @@
  * and fields annotated by <code>&#064;Parameter</code>  will be initialized
  * with the data values in the <code>&#064;Parameters</code> method.
  *
+ * <p>
+ * The parameters can be provided as an array, too:
+ * 
+ * <pre>
+ * &#064;Parameters
+ * public static Object[][] data() {
+ * 	return new Object[][] { { 0, 0 }, { 1, 1 }, { 2, 1 }, { 3, 2 }, { 4, 3 },
+ * 			{ 5, 5 }, { 6, 8 } };
+ * }
+ * </pre>
+ * 
+ * <h3>Tests with single parameter</h3>
+ * <p>
+ * If your test needs a single parameter only, you don't have to wrap it with an
+ * array. Instead you can provide an <code>Iterable</code> or an array of
+ * objects.
+ * <pre>
+ * &#064;Parameters
+ * public static Iterable&lt;? extends Object&gt; data() {
+ * 	return Arrays.asList(&quot;first test&quot;, &quot;second test&quot;);
+ * }
+ * </pre>
+ * <p>
+ * or
+ * <pre>
+ * &#064;Parameters
+ * public static Object[] data() {
+ * 	return new Object[] { &quot;first test&quot;, &quot;second test&quot; };
+ * }
+ * </pre>
+ *
  * @since 4.0
  */
 public class Parameterized extends Suite {
@@ -281,15 +313,25 @@ protected List<Runner> getChildren() {
         return fRunners;
     }
 
+    private Runner createRunnerWithNotNormalizedParameters(String pattern,
+            int index, Object parametersOrSingleParameter)
+            throws InitializationError {
+        Object[] parameters= (parametersOrSingleParameter instanceof Object[]) ? (Object[]) parametersOrSingleParameter
+            : new Object[] { parametersOrSingleParameter };
+        return createRunner(pattern, index, parameters);
+    }
+
     protected Runner createRunner(String pattern, int index, Object[] parameters) throws InitializationError {
         return new TestClassRunnerForParameters(getTestClass().getJavaClass(), pattern, index, parameters);
     }
 
     @SuppressWarnings("unchecked")
-    private Iterable<Object[]> allParameters() throws Throwable {
+    private Iterable<Object> allParameters() throws Throwable {
         Object parameters = getParametersMethod().invokeExplosively(null);
         if (parameters instanceof Iterable) {
-            return (Iterable<Object[]>) parameters;
+            return (Iterable<Object>) parameters;
+        } else if (parameters instanceof Object[]) {
+            return Arrays.asList((Object[]) parameters);
         } else {
             throw parametersMethodReturnedWrongType();
         }
@@ -308,12 +350,13 @@ private FrameworkMethod getParametersMethod() throws Exception {
                 + getTestClass().getName());
     }
 
-    private List<Runner> createRunnersForParameters(Iterable<Object[]> allParameters, String namePattern) throws Exception {
+    private List<Runner> createRunnersForParameters(Iterable<Object> allParameters, String namePattern) throws Exception {
         try {
             int i = 0;
             List<Runner> children = new ArrayList<Runner>();
-            for (Object[] parametersOfSingleTest : allParameters) {
-                children.add(createRunner(namePattern, i++, parametersOfSingleTest));
+            for (Object parametersOfSingleTest : allParameters) {
+                children.add(createRunnerWithNotNormalizedParameters(
+                    namePattern, i++, parametersOfSingleTest));
             }
             return children;
         } catch (ClassCastException e) {

src/test/java/org/junit/tests/running/classes/ParameterizedTestTest.java

@@ -1,5 +1,6 @@
 package org.junit.tests.running.classes;
 
+import static java.util.Arrays.asList;
 import static org.hamcrest.CoreMatchers.containsString;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertThat;
@@ -314,25 +315,6 @@ public void meaningfulFailureWhenParametersNotPublic() throws Exception {
         assertEquals(expected, result.getFailures().get(0).getMessage());
     }
 
-    @RunWith(Parameterized.class)
-    static public class WrongElementType {
-        @Parameters
-        public static Iterable<String> data() {
-            return Arrays.asList("a", "b", "c");
-        }
-
-        @Test
-        public void aTest() {
-        }
-    }
-
-    @Test
-    public void meaningfulFailureWhenParametersAreNotArrays() {
-        assertThat(
-                testResult(WrongElementType.class).toString(),
-                containsString("WrongElementType.data() must return an Iterable of arrays."));
-    }
-
     @RunWith(Parameterized.class)
     static public class ParametersNotIterable {
         @Parameters
@@ -372,4 +354,80 @@ public void aTest() {
     public void exceptionWhenPrivateConstructor() throws Throwable {
         new Parameterized(PrivateConstructor.class);
     }
+
+    @RunWith(Parameterized.class)
+    static public class FibonacciTestWithArray {
+        @Parameters(name= "{index}: fib({0})={1}")
+        public static Object[][] data() {
+            return new Object[][] { { 0, 0 }, { 1, 1 }, { 2, 1 },
+                { 3, 2 }, { 4, 3 }, { 5, 5 }, { 6, 8 } };
+        }
+
+        private final int fInput;
+
+        private final int fExpected;
+
+        public FibonacciTestWithArray(int input, int expected) {
+            fInput= input;
+            fExpected= expected;
+        }
+
+        @Test
+        public void test() {
+            assertEquals(fExpected, fib(fInput));
+        }
+
+        private int fib(int x) {
+            return 0;
+        }
+    }
+
+    @Test
+    public void runsEveryTestOfArray() {
+        Result result= JUnitCore.runClasses(FibonacciTestWithArray.class);
+        assertEquals(7, result.getRunCount());
+    }
+
+    @RunWith(Parameterized.class)
+    static public class SingleArgumentTestWithArray {
+        @Parameters
+        public static Object[] data() {
+            return new Object[] { "first test", "second test" };
+        }
+
+        public SingleArgumentTestWithArray(Object argument) {
+        }
+
+        @Test
+        public void aTest() {
+        }
+    }
+
+    @Test
+    public void runsForEverySingleArgumentOfArray() {
+        Result result= JUnitCore.runClasses(SingleArgumentTestWithArray.class);
+        assertEquals(2, result.getRunCount());
+    }
+
+    @RunWith(Parameterized.class)
+    static public class SingleArgumentTestWithIterable {
+        @Parameters
+        public static Iterable<? extends Object> data() {
+            return asList("first test", "second test");
+        }
+
+        public SingleArgumentTestWithIterable(Object argument) {
+        }
+
+        @Test
+        public void aTest() {
+        }
+  	}
+
+    @Test
+    public void runsForEverySingleArgumentOfIterable() {
+        Result result= JUnitCore
+                .runClasses(SingleArgumentTestWithIterable.class);
+        assertEquals(2, result.getRunCount());
+    }
 }