Support CSV headers with {argumentsWithNames} display name patterns

Prior to this commit, display names using CSV header names did not work
properly when using the {argumentsWithNames} display name pattern for
parameterized tests. Specifically, both the parameter name and the CSV
header name were present in the display name, leading to duplication --
for example:

[1] fruit = FRUIT = apple

This commit ensures that the parameter name is not displayed when the
user has enabled the useHeadersInDisplayName flag in @⁠CsvSource and
@⁠CsvFileSource. With this change the above display name is now
properly generated as follows (with the superfluous "fruit = " removed).

[1] FRUIT = apple

See #4716
Closes #4783

Author: sbrannen

documentation/src/docs/asciidoc/release-notes/release-notes-6.0.0-RC1.adoc

@@ -35,7 +35,11 @@ repository on GitHub.
 [[release-notes-6.0.0-RC1-junit-jupiter-bug-fixes]]
 ==== Bug Fixes
 
-* ❓
+* CSV headers are now properly supported with the default display name pattern and the
+  explicit `{argumentsWithNames}` display name pattern for parameterized tests that
+  utilize the `useHeadersInDisplayName` flag in `@CsvSource` and `@CsvFileSource`.
+  Specifically, the parameter name is no longer duplicated in the display name when a CSV
+  header is desired instead.
 
 [[release-notes-6.0.0-RC1-junit-jupiter-deprecations-and-breaking-changes]]
 ==== Deprecations and Breaking Changes

documentation/src/docs/asciidoc/user-guide/writing-tests.adoc

@@ -2236,7 +2236,7 @@ Using a text block, the previous example can be implemented as follows.
 
 [source,java,indent=0]
 ----
-@ParameterizedTest(name = "[{index}] {arguments}")
+@ParameterizedTest
 @CsvSource(useHeadersInDisplayName = true, textBlock = """
 	FRUIT,         RANK
 	apple,         1

documentation/src/test/java/example/ParameterizedTestDemo.java

@@ -341,7 +341,7 @@ void testWithCsvFileSourceFromFile(String country, int reference) {
 		assertNotEquals(0, reference);
 	}
 
-	@ParameterizedTest(name = "[{index}] {arguments}")
+	@ParameterizedTest
 	@CsvFileSource(resources = "/two-column.csv", useHeadersInDisplayName = true)
 	void testWithCsvFileSourceAndHeaders(String country, int reference) {
 		assertNotNull(country);

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

@@ -163,8 +163,8 @@ private PartialFormatters createPartialFormatters(String displayName,
 			ParameterizedDeclarationContext<?> declarationContext, int argumentMaxLength) {
 
 		PartialFormatter argumentsWithNamesFormatter = new CachingByArgumentsLengthPartialFormatter(
-			length -> new MessageFormatPartialFormatter(argumentsWithNamesPattern(length, declarationContext),
-				argumentMaxLength));
+			length -> new MessageFormatPartialFormatter(argumentsPattern(length), argumentMaxLength, true,
+				declarationContext.getResolverFacade()));
 
 		PartialFormatter argumentSetNameFormatter = new ArgumentSetNameFormatter(
 			declarationContext.getAnnotationName());
@@ -185,15 +185,6 @@ private PartialFormatters createPartialFormatters(String displayName,
 		return formatters;
 	}
 
-	private static String argumentsWithNamesPattern(int length, ParameterizedDeclarationContext<?> declarationContext) {
-		ResolverFacade resolverFacade = declarationContext.getResolverFacade();
-		return IntStream.range(0, length) //
-				.mapToObj(index -> resolverFacade.getParameterName(index)//
-						.map(name -> name + " = ").orElse("") //
-						+ "{" + index + "}") //
-				.collect(joining(", "));
-	}
-
 	private static String argumentsPattern(int length) {
 		return IntStream.range(0, length) //
 				.mapToObj(index -> "{" + index + "}") //
@@ -238,10 +229,19 @@ private static class MessageFormatPartialFormatter implements PartialFormatter {
 
 		private final MessageFormat messageFormat;
 		private final int argumentMaxLength;
+		private final boolean generateNameValuePairs;
+		private final @Nullable ResolverFacade resolverFacade;
 
 		MessageFormatPartialFormatter(String pattern, int argumentMaxLength) {
+			this(pattern, argumentMaxLength, false, null);
+		}
+
+		MessageFormatPartialFormatter(String pattern, int argumentMaxLength, boolean generateNameValuePairs,
+				@Nullable ResolverFacade resolverFacade) {
 			this.messageFormat = new MessageFormat(pattern);
 			this.argumentMaxLength = argumentMaxLength;
+			this.generateNameValuePairs = generateNameValuePairs;
+			this.resolverFacade = resolverFacade;
 		}
 
 		// synchronized because MessageFormat is not thread-safe
@@ -262,9 +262,17 @@ public synchronized void append(ArgumentsContext context, StringBuffer result) {
 					String prefix = "";
 
 					if (argument instanceof ParameterNameAndArgument parameterNameAndArgument) {
+						// This supports the useHeadersInDisplayName attributes in @CsvSource and @CsvFileSource.
 						prefix = parameterNameAndArgument.getName() + " = ";
 						argument = parameterNameAndArgument.getPayload();
 					}
+					else if (this.generateNameValuePairs && this.resolverFacade != null) {
+						Optional<String> parameterName = this.resolverFacade.getParameterName(i);
+						if (parameterName.isPresent()) {
+							// This supports the {argumentsWithNames} pattern.
+							prefix = parameterName.get() + " = ";
+						}
+					}
 
 					if (argument instanceof Character ch) {
 						result[i] = prefix + (quoteTextArguments ? QuoteUtils.quote(ch) : ch);

jupiter-tests/src/test/java/org/junit/jupiter/params/ParameterizedInvocationNameFormatterTests.java

@@ -406,9 +406,8 @@ void quotedStringsForArgumentsWithNamesAndParameterNameAndArgument() {
 			var name1 = format(formatter, 1, arguments(new ParameterNameAndArgument("FRUIT", "apple"), 42));
 			var name2 = format(formatter, 2, arguments(new ParameterNameAndArgument("FRUCHT", "Banane"), 99));
 
-			// TODO Remove "fruit = " once #4783 has been fixed.
-			assertThat(name1).isEqualTo("[1] fruit = FRUIT = \"apple\", ranking = 42");
-			assertThat(name2).isEqualTo("[2] fruit = FRUCHT = \"Banane\", ranking = 99");
+			assertThat(name1).isEqualTo("[1] FRUIT = \"apple\", ranking = 42");
+			assertThat(name2).isEqualTo("[2] FRUCHT = \"Banane\", ranking = 99");
 		}
 
 	}

jupiter-tests/src/test/java/org/junit/jupiter/params/ParameterizedTestIntegrationTests.java

@@ -1264,7 +1264,7 @@ void executesWithRepeatableCsvFileSource(String methodName) {
 			results.allEvents().assertThatEvents() //
 					.haveExactly(1, event(test(), displayName("[1] column1 = foo, column2 = 1"),
 						finishedWithFailure(message("foo 1")))) //
-					.haveExactly(1, event(test(), displayName("[5] column1 = FRUIT = apple, column2 = RANK = 1"),
+					.haveExactly(1, event(test(), displayName("[5] FRUIT = apple, RANK = 1"),
 						finishedWithFailure(message("apple 1"))));
 		}