Fix regression when creating human-readable test names

Prior to this commit Arrays.copyOf() was used without specifying the
resulting array type in order to create a human-readable names for
parameterized tests. Now, type `Object[]` is passed as an argument to
ensure the resulting array may contain any valid instance, here an
instance of `String`.

Fixes #1836

Author: sormuras

junit-jupiter-params/src/main/java/org/junit/jupiter/params/ParameterizedTestNameFormatter.java

@@ -73,7 +73,7 @@ private String prepareMessageFormatPattern(int invocationIndex, Object[] argumen
 
 	private Object[] makeReadable(MessageFormat format, Object[] arguments) {
 		Format[] formats = format.getFormatsByArgumentIndex();
-		Object[] result = Arrays.copyOf(arguments, Math.min(arguments.length, formats.length));
+		Object[] result = Arrays.copyOf(arguments, Math.min(arguments.length, formats.length), Object[].class);
 		for (int i = 0; i < result.length; i++) {
 			if (formats[i] == null) {
 				result[i] = StringUtils.nullSafeToString(arguments[i]);

junit-jupiter-params/src/test/java/org/junit/jupiter/params/ParameterizedTestNameFormatterTests.java

@@ -115,6 +115,14 @@ void formatDoesNotAlterArgumentsArray() {
 		assertArrayEquals(expected, actual);
 	}
 
+	@Test
+	void formatDoesNotRaiseAnArrayStoreException() {
+		ParameterizedTestNameFormatter formatter = new ParameterizedTestNameFormatter("{0} -> {1}", "enigma");
+
+		Object[] arguments = new Number[] { 1, 2 };
+		assertEquals("1 -> 2", formatter.format(1, arguments));
+	}
+
 	@Test
 	void throwsReadableExceptionForInvalidPattern() {
 		ParameterizedTestNameFormatter formatter = new ParameterizedTestNameFormatter("{index", "enigma");

junit-jupiter-params/src/test/kotlin/org/junit/jupiter/params/aggregator/DisplayNameTests.kt

@@ -22,12 +22,14 @@ object DisplayNameTests {
     fun data() = arrayOf(
             arrayOf("A", 1),
             arrayOf("B", 2),
-            arrayOf("C", 3)
+            arrayOf("C", 3),
+            arrayOf("", 4), // empty is okay
+            arrayOf(null, 5) // null was the problem
     )
 
     @ParameterizedTest
     @MethodSource("data")
-    fun test(char: String, number: Int, info: TestInfo) {
+    fun test(char: String?, number: Int, info: TestInfo) {
         assertEquals("[$number] $char, $number", info.displayName)
     }
 }