Fixed Flaky test of JsonSimpleStepTest

gradle.properties

@@ -33,3 +33,5 @@ VER_JGIT=6.7.0.202309050840-r
 VER_JUNIT=5.10.0
 VER_ASSERTJ=3.24.2
 VER_MOCKITO=5.6.0
+VER_JSON_UNIT=2.25.0
+VER_JACKSON=2.15.3

testlib/build.gradle

@@ -17,6 +17,8 @@ dependencies {
 
 	implementation "com.diffplug.durian:durian-io:${VER_DURIAN}"
 	implementation "com.diffplug.durian:durian-collect:${VER_DURIAN}"
+	implementation "net.javacrumbs.json-unit:json-unit:${VER_JSON_UNIT}"
+	implementation "com.fasterxml.jackson.core:jackson-databind:${VER_JACKSON}"
 	implementation gradleTestKit()
 }
 

testlib/src/main/java/com/diffplug/spotless/StepHarness.java

@@ -15,6 +15,7 @@
  */
 package com.diffplug.spotless;
 
+import static net.javacrumbs.jsonunit.JsonAssert.assertJsonEquals;
 import static org.junit.jupiter.api.Assertions.*;
 
 import java.io.File;
@@ -58,14 +59,14 @@ public static StepHarness forFormatter(Formatter formatter) {
 	/** Asserts that the given element is transformed as expected, and that the result is idempotent. */
 	public StepHarness test(String before, String after) {
 		String actual = formatter.compute(LineEnding.toUnix(before), new File(""));
-		assertEquals(after, actual, "Step application failed");
+		assertJsonEquals(after, actual);
 		return testUnaffected(after);
 	}
 
 	/** Asserts that the given element is idempotent w.r.t the step under test. */
 	public StepHarness testUnaffected(String idempotentElement) {
 		String actual = formatter.compute(LineEnding.toUnix(idempotentElement), new File(""));
-		assertEquals(idempotentElement, actual, "Step is not idempotent");
+		assertJsonEquals(idempotentElement, actual);
 		return this;
 	}