test: test case reproducing the npm configuration cache issue diffplug#2372

Author: jGleitz

plugin-gradle/src/test/java/com/diffplug/gradle/spotless/NpmTestsWithoutNpmInstallationTest.java

@@ -177,4 +177,13 @@ void useNpmNextToConfiguredNodePluginFromNodeGradlePlugin() throws Exception {
 			throw e;
 		}
 	}
+
+	@Test
+	public void supportsConfigurationCache() throws Exception {
+		setFile("build.gradle").toResource("com/diffplug/gradle/spotless/NpmTestsWithoutNpmInstallationTest_gradle_node_plugin_example_1.gradle");
+		setFile("test.ts").toResource("npm/prettier/config/typescript.dirty");
+		final BuildResult spotlessApply = gradleRunner().withArguments("--stacktrace", "--configuration-cache", "spotlessApply").build();
+		Assertions.assertThat(spotlessApply.getOutput()).contains("BUILD SUCCESSFUL");
+		assertFile("test.ts").sameAsResource("npm/prettier/config/typescript.configfile_prettier_2.clean");
+	}
 }