And a test to demonstrate that it works.

Author: nedtwigg

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

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2020-2021 DiffPlug
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.diffplug.gradle.spotless;
+
+import java.io.IOException;
+
+import org.gradle.testkit.runner.BuildResult;
+import org.gradle.testkit.runner.GradleRunner;
+import org.junit.jupiter.api.Test;
+
+public class ConfigurationCacheDaemonLocalTest extends GradleIntegrationHarness {
+	@Override
+	protected GradleRunner gradleRunner() throws IOException {
+		setFile("gradle.properties").toContent("org.gradle.unsafe.configuration-cache=true");
+		return super.gradleRunner().withGradleVersion(GradleVersionSupport.CONFIGURATION_CACHE.version);
+	}
+
+	@Test
+	public void gjf() throws IOException {
+		setFile("build.gradle").toLines(
+				"plugins {",
+				"    id 'com.diffplug.spotless-setup'",
+				"    id 'com.diffplug.spotless'",
+				"}",
+				"repositories { mavenCentral() }",
+				"spotlessSetup {",
+				"    enableConfigCacheDaemonLocal = true",
+				"}",
+				"spotless {",
+				"    java {",
+				"        target file('test.java')",
+				"        googleJavaFormat('1.2')",
+				"    }",
+				"}");
+
+		// first run works
+		setFile("test.java").toResource("java/googlejavaformat/JavaCodeUnformatted.test");
+		gradleRunner().withArguments("spotlessApply").build();
+		assertFile("test.java").sameAsResource("java/googlejavaformat/JavaCodeFormatted.test");
+
+		// and it keeps working!
+		gradleRunner().withArguments("spotlessApply", "--stacktrace").build();
+		gradleRunner().withArguments("spotlessApply").build();
+		gradleRunner().withArguments("spotlessApply").build();
+
+		setFile("test.java").toResource("java/googlejavaformat/JavaCodeUnformatted.test");
+		gradleRunner().withArguments("spotlessCheck").buildAndFail();
+		gradleRunner().withArguments("spotlessApply").build();
+		assertFile("test.java").sameAsResource("java/googlejavaformat/JavaCodeFormatted.test");
+
+		BuildResult failure = gradleRunner().withDebug(true).withArguments("spotlessApply", "--stacktrace").buildAndFail();
+		failure.getOutput().contains("Spotless daemon-local cache is stale. Regenerate the cache with\n" +
+				"  rm -rf .gradle/configuration-cache\n" +
+				"For more information see #123\n");
+	}
+}