From 531da015e108346695a69872335b6bd9ae3d55a5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20Basl=C3=A9?= <simon.basle@broadcom.com>
Date: Wed, 15 May 2024 11:01:30 +0200
Subject: [PATCH] Improve MediaTypeAssert to-string-equality assertions

This commit introduces a `isNotEqualTo(String)` assertion in order to
avoid false negatives when using the default Object-based assertion.

This is a risk since MediaTypeAssert has a `isEqualTo(String)` method
that overrides the base object method and parses the provided String
into a MediaType. Users may thus be tempted to use the reverse assertion
and expect the same parsing behaviour.

This commit also adds tests around the String parsing and the isNotEqual
cases.

Closes gh-32756
---
 .../test/http/MediaTypeAssert.java            | 20 ++++--
 .../test/http/MediaTypeAssertTests.java       | 65 ++++++++++++++++++-
 2 files changed, 78 insertions(+), 7 deletions(-)

diff --git a/spring-test/src/main/java/org/springframework/test/http/MediaTypeAssert.java b/spring-test/src/main/java/org/springframework/test/http/MediaTypeAssert.java
index 6f002c8f6d..5c6077cce6 100644
--- a/spring-test/src/main/java/org/springframework/test/http/MediaTypeAssert.java
+++ b/spring-test/src/main/java/org/springframework/test/http/MediaTypeAssert.java
@@ -49,10 +49,21 @@ public class MediaTypeAssert extends AbstractObjectAssert<MediaTypeAssert, Media
 	/**
 	 * Verify that the actual media type is equal to the given string
 	 * representation.
-	 * @param expected the expected media type
+	 * @param mediaType the expected media type, as a String to be parsed
+	 * into a MediaType
+*/
+	public MediaTypeAssert isEqualTo(String mediaType) {
+		return isEqualTo(parseMediaType(mediaType));
+	}
+
+	/**
+	 * Verify that the actual media type is not equal to the given string
+	 * representation.
+	 * @param mediaType the given media type, as a String to be parsed
+	 * into a MediaType
 	 */
-	public MediaTypeAssert isEqualTo(String expected) {
-		return isEqualTo(parseMediaType(expected));
+	public MediaTypeAssert isNotEqualTo(String mediaType) {
+		return isNotEqualTo(parseMediaType(mediaType));
 	}
 
 	/**
@@ -84,7 +95,8 @@ public class MediaTypeAssert extends AbstractObjectAssert<MediaTypeAssert, Media
 	 * // Check that actual is compatible with "text/plain"
 	 * assertThat(mediaType).isCompatibleWith("text/plain");
 	 * </code></pre>
-	 * @param mediaType the media type with which to compare
+	 * @param mediaType the media type with which to compare, as a String
+	 * to be parsed into a MediaType
 	 */
 	public MediaTypeAssert isCompatibleWith(String mediaType) {
 		return isCompatibleWith(parseMediaType(mediaType));
diff --git a/spring-test/src/test/java/org/springframework/test/http/MediaTypeAssertTests.java b/spring-test/src/test/java/org/springframework/test/http/MediaTypeAssertTests.java
index 232d25400f..c8b1d71ee7 100644
--- a/spring-test/src/test/java/org/springframework/test/http/MediaTypeAssertTests.java
+++ b/spring-test/src/test/java/org/springframework/test/http/MediaTypeAssertTests.java
@@ -43,19 +43,35 @@ class MediaTypeAssertTests {
 	}
 
 	@Test
-	void isEqualWhenSameShouldPass() {
+	void isEqualWhenActualIsNullStringShouldFail() {
+		assertThatExceptionOfType(AssertionError.class)
+				.isThrownBy(() -> assertThat(null).isEqualTo("text/html"))
+				.withMessageContaining("Media type");
+	}
+
+	@Test
+	void isEqualWhenSameStringShouldPass() {
 		assertThat(mediaType("application/json")).isEqualTo("application/json");
 	}
 
 	@Test
-	void isEqualWhenDifferentShouldFail() {
+	void isEqualWhenDifferentStringShouldFail() {
 		assertThatExceptionOfType(AssertionError.class)
 				.isThrownBy(() -> assertThat(mediaType("application/json")).isEqualTo("text/html"))
 				.withMessageContaining("Media type");
 	}
 
 	@Test
-	void isEqualWhenActualIsNullShouldFail() {
+	void isEqualInvalidStringShouldFail() {
+		assertThatExceptionOfType(AssertionError.class)
+				.isThrownBy(() -> assertThat(mediaType("application/json")).isEqualTo("example of a bad value"))
+				.withMessageContaining("[Media type]")
+				.withMessageEndingWith("To be a valid media type but got:\n" +
+						"  \"Invalid mime type \"example of a bad value\": does not contain '/'\"\n");
+	}
+
+	@Test
+	void isEqualWhenActualIsNullTypeShouldFail() {
 		assertThatExceptionOfType(AssertionError.class)
 				.isThrownBy(() -> assertThat(null).isEqualTo(MediaType.APPLICATION_JSON))
 				.withMessageContaining("Media type");
@@ -73,6 +89,49 @@ class MediaTypeAssertTests {
 				.withMessageContaining("Media type");
 	}
 
+	@Test
+	void isNotEqualWhenActualIsNullStringShouldPass() {
+		assertThat(null).isNotEqualTo("application/json");
+	}
+
+	@Test
+	void isNotEqualWhenDifferentStringShouldPass() {
+		assertThat(mediaType("application/json")).isNotEqualTo("text/html");
+	}
+
+	@Test
+	void isNotEqualWhenSameStringShouldFail() {
+		assertThatExceptionOfType(AssertionError.class)
+				.isThrownBy(() -> assertThat(mediaType("application/json")).isNotEqualTo("application/json"))
+				.withMessageContaining("Media type");
+	}
+
+	@Test
+	void isNotEqualInvalidStringShouldFail() {
+		assertThatExceptionOfType(AssertionError.class)
+				.isThrownBy(() -> assertThat(mediaType("application/json")).isNotEqualTo("example of a bad value"))
+				.withMessageContaining("[Media type]")
+				.withMessageEndingWith("To be a valid media type but got:\n" +
+						"  \"Invalid mime type \"example of a bad value\": does not contain '/'\"\n");
+	}
+
+	@Test
+	void isNotEqualWhenActualIsNullTypeShouldPass() {
+		assertThat(null).isNotEqualTo(MediaType.APPLICATION_JSON);
+	}
+
+	@Test
+	void isNotEqualWhenDifferentTypeShouldPass() {
+		assertThat(mediaType("application/json")).isNotEqualTo(MediaType.TEXT_HTML);
+	}
+
+	@Test
+	void isNotEqualWhenSameTypeShouldFail() {
+		assertThatExceptionOfType(AssertionError.class)
+				.isThrownBy(() -> assertThat(mediaType("application/json")).isNotEqualTo(MediaType.APPLICATION_JSON))
+				.withMessageContaining("Media type");
+	}
+
 	@Test
 	void isCompatibleWhenSameShouldPass() {
 		assertThat(mediaType("application/json")).isCompatibleWith("application/json");