Migrate tests to JUnit 5

Main changes:
 * all tests use JUnit Jupiter APIs and assertions
 * remove public modifiers from test classes and test methods because they are
   unnecessary with JUnit Jupiter
 * replace JVM version assumptions with `@EnabledOnJre` annotations that
   support version ranges
 * replace OS assumptions with `@EnabledOnOs` and `@DisabledOnOs`
 * enable JUnit Jupiter in Gradle build scripts for the test task
   with `useJUnitPlatform()`

Author: lutovich

_ext/eclipse-base/src/test/java/com/diffplug/spotless/extra/eclipse/base/SpotlessEclipseFrameworkTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 DiffPlug
+ * Copyright 2016-2021 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -35,11 +35,11 @@
 import org.eclipse.core.runtime.Status;
 import org.eclipse.equinox.log.ExtendedLogReaderService;
 import org.eclipse.equinox.log.ExtendedLogService;
-import org.junit.After;
-import org.junit.AfterClass;
-import org.junit.Before;
-import org.junit.BeforeClass;
-import org.junit.Test;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 import org.osgi.framework.Bundle;
 import org.osgi.framework.BundleContext;
 import org.osgi.framework.BundleException;
@@ -52,7 +52,7 @@
 import com.diffplug.spotless.extra.eclipse.base.service.SingleSlf4JService;
 
 /** Integration tests */
-public class SpotlessEclipseFrameworkTest {
+class SpotlessEclipseFrameworkTest {
 
 	private final static String TEST_LOGGER_NAME = SpotlessEclipseFrameworkTest.class.getSimpleName();
 	private final static String CUSTOM_PREFIX = "prefix\t";
@@ -62,8 +62,8 @@ public class SpotlessEclipseFrameworkTest {
 
 	private static boolean TREAT_ERROR_AS_EXCEPTION = false;
 
-	@BeforeClass
-	public static void frameworkTestSetup() throws BundleException {
+	@BeforeAll
+	static void frameworkTestSetup() throws BundleException {
 		//Prepare interception of SLF4J messages to System.out
 		SLF4J_RECEIVER = new Slf4JMesssageListener();
 
@@ -87,29 +87,29 @@ public void registerServices(SpotlessEclipseServiceConfig config) {
 		});
 	}
 
-	@AfterClass
-	public static void deregisterSlf4JReceiver() {
+	@AfterAll
+	static void deregisterSlf4JReceiver() {
 		SLF4J_RECEIVER.deregister();
 	}
 
 	private EclipseMessageListener eclipseMessageListener;
 
-	@Before
-	public void eclipseReceiverSetup() {
+	@BeforeEach
+	void eclipseReceiverSetup() {
 		ExtendedLogReaderService service = getService(ExtendedLogReaderService.class);
 		eclipseMessageListener = new EclipseMessageListener();
 		service.addLogListener(eclipseMessageListener);
 		SLF4J_RECEIVER.clear();
 	}
 
-	@After
-	public void logReceiverTearDown() {
+	@AfterEach
+	void logReceiverTearDown() {
 		ExtendedLogReaderService service = getService(ExtendedLogReaderService.class);
 		service.removeLogListener(eclipseMessageListener);
 	}
 
 	@Test
-	public void testCustomizedLogMessage() {
+	void testCustomizedLogMessage() {
 		ResourcesPlugin.getPlugin().getLog().log(new Status(IStatus.ERROR, "Some plugin", "Hello World!"));
 		assertSlf4J()
 				.as("Error message logged.").received("Hello World!").contains(TEST_LOGGER_NAME)
@@ -121,7 +121,7 @@ public void testCustomizedLogMessage() {
 	}
 
 	@Test
-	public void testCustomizedLogException() {
+	void testCustomizedLogException() {
 		assertThatExceptionOfType(IllegalArgumentException.class)
 				.isThrownBy(() -> {
 					try {
@@ -135,7 +135,7 @@ public void testCustomizedLogException() {
 	}
 
 	@Test
-	public void testPluginLog() {
+	void testPluginLog() {
 		List<Integer> logLevels = Arrays.asList(IStatus.CANCEL, IStatus.ERROR, IStatus.INFO, IStatus.OK, IStatus.WARNING);
 		List<Integer> enabledLogLevels = Arrays.asList(IStatus.ERROR, IStatus.WARNING);
 		List<Integer> disabledLogLevels = logLevels.stream().filter(level -> !enabledLogLevels.contains(level)).collect(Collectors.toList());
@@ -153,7 +153,7 @@ public void testPluginLog() {
 	}
 
 	@Test
-	public void testLogServiceLevel() {
+	void testLogServiceLevel() {
 		ExtendedLogService service = getService(ExtendedLogService.class);
 		assertThat(service.isErrorEnabled()).as("Error log level is enabled").isTrue();
 		assertThat(service.isWarnEnabled()).as("Warning log level is enabled").isTrue();
@@ -163,7 +163,7 @@ public void testLogServiceLevel() {
 	}
 
 	@Test
-	public void testLogServiceLog() {
+	void testLogServiceLog() {
 		ExtendedLogService service = getService(ExtendedLogService.class);
 		service.info("Log Info");
 		service.warn("Log Warn");
@@ -174,7 +174,7 @@ public void testLogServiceLog() {
 
 	@Test
 	@Deprecated
-	public void testLogServiceLog_3_12() {
+	void testLogServiceLog_3_12() {
 		ExtendedLogService service = getService(ExtendedLogService.class);
 		service.log(SingleSlf4JService.LOG_INFO, "Log Info");
 		try {

_ext/eclipse-base/src/test/java/com/diffplug/spotless/extra/eclipse/base/osgi/BundleSetTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 DiffPlug
+ * Copyright 2016-2021 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,75 +16,63 @@
 package com.diffplug.spotless.extra.eclipse.base.osgi;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.junit.Assert.*;
+import static org.junit.jupiter.api.Assertions.*;
 
 import java.util.Arrays;
 
-import org.junit.Before;
-import org.junit.Test;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 import org.osgi.framework.Bundle;
 import org.osgi.framework.BundleException;
 
-public class BundleSetTest {
+class BundleSetTest {
 
 	BundleSet instance;
 
-	@Before
-	public void initialize() {
+	@BeforeEach
+	void initialize() {
 		instance = new BundleSet();
 	}
 
 	@Test
-	public void testAddGet() throws BundleException {
+	void testAddGet() throws BundleException {
 		Bundle testBundle1 = new TestBundle(1, "a");
 		Bundle testBundle2 = new TestBundle(2, "b");
 		instance.add(testBundle1);
 		instance.add(testBundle2);
-		assertEquals("Get by ID 1", testBundle1, instance.get(1));
-		assertEquals("Get by ID 2", testBundle2, instance.get(2));
-		assertEquals("Get by symbolic name 'a'", testBundle1, instance.get("a"));
-		assertEquals("Get by symbolic name 'b'", testBundle2, instance.get("b"));
-		assertTrue("Contains all", instance.getAll().containsAll(Arrays.asList(testBundle1, testBundle2)));
+		assertEquals(testBundle1, instance.get(1), "Get by ID 1");
+		assertEquals(testBundle2, instance.get(2), "Get by ID 2");
+		assertEquals(testBundle1, instance.get("a"), "Get by symbolic name 'a'");
+		assertEquals(testBundle2, instance.get("b"), "Get by symbolic name 'b'");
+		assertTrue(instance.getAll().containsAll(Arrays.asList(testBundle1, testBundle2)), "Contains all");
 	}
 
 	@Test
-	public void testSameSymbolicName() throws BundleException {
+	void testSameSymbolicName() throws BundleException {
 		final String symbolicName = "sym.a";
 		final long id1 = 12345;
 		final long id2 = 23456;
 		Bundle testBundle1 = new TestBundle(id1, symbolicName);
 		Bundle testBundle2 = new TestBundle(id2, symbolicName);
 		instance.add(testBundle1);
-		boolean exceptionCaught = false;
-		try {
-			instance.add(testBundle2);
-		} catch (BundleException e) {
-			exceptionCaught = true;
-			assertThat(e.getMessage()).as("BundleException does not contain symbolic name.").contains(symbolicName);
-			assertThat(e.getMessage()).as("BundleException does not contain ID of exisiting bundle.").contains(Long.toString(id1));
-			assertThat(e.getMessage()).as("BundleException does not contain ID of new bundle.").contains(Long.toString(id2));
-		}
-		assertThat(exceptionCaught).as("No BundleException thrown for duplicate symblic name.").isTrue();
+		BundleException e = assertThrows(BundleException.class, () -> instance.add(testBundle2));
+		assertThat(e.getMessage()).as("BundleException does not contain symbolic name.").contains(symbolicName);
+		assertThat(e.getMessage()).as("BundleException does not contain ID of exisiting bundle.").contains(Long.toString(id1));
+		assertThat(e.getMessage()).as("BundleException does not contain ID of new bundle.").contains(Long.toString(id2));
 	}
 
 	@Test
-	public void testSameID() throws BundleException {
+	void testSameID() throws BundleException {
 		final String symbolicName1 = "sym.a";
 		final String symbolicName2 = "sym.b";
 		final long id = 12345;
 		Bundle testBundle1 = new TestBundle(id, symbolicName1);
 		Bundle testBundle2 = new TestBundle(id, symbolicName2);
 		instance.add(testBundle1);
-		boolean exceptionCaught = false;
-		try {
-			instance.add(testBundle2);
-		} catch (BundleException e) {
-			exceptionCaught = true;
-			assertThat(e.getMessage()).as("BundleException does not contain ID.").contains(Long.toString(id));
-			assertThat(e.getMessage()).as("BundleException does not contain symbolic name of exisiting bundle.").contains(symbolicName1);
-			assertThat(e.getMessage()).as("BundleException does not contain symbolic name of new bundle.").contains(symbolicName2);
-		}
-		assertThat(exceptionCaught).as("No BundleException thrown for duplicate symblic name.").isTrue();
+		BundleException e = assertThrows(BundleException.class, () -> instance.add(testBundle2));
+		assertThat(e.getMessage()).as("BundleException does not contain ID.").contains(Long.toString(id));
+		assertThat(e.getMessage()).as("BundleException does not contain symbolic name of exisiting bundle.").contains(symbolicName1);
+		assertThat(e.getMessage()).as("BundleException does not contain symbolic name of new bundle.").contains(symbolicName2);
 	}
 
 }

_ext/eclipse-base/src/test/java/com/diffplug/spotless/extra/eclipse/base/osgi/ServiceCollectionTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 DiffPlug
+ * Copyright 2016-2021 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,28 +16,29 @@
 package com.diffplug.spotless.extra.eclipse.base.osgi;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.*;
 
 import java.util.HashMap;
 
 import org.assertj.core.api.AbstractAssert;
-import org.junit.Before;
-import org.junit.Test;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 import org.osgi.framework.Bundle;
 import org.osgi.framework.ServiceException;
 import org.osgi.framework.ServiceReference;
 
-public class ServiceCollectionTest {
+class ServiceCollectionTest {
 
 	ServiceCollection instance;
 
-	@Before
-	public void initialize() {
+	@BeforeEach
+	void initialize() {
 		Bundle systemBundle = new TestBundle(0, "test.system");
 		instance = new ServiceCollection(systemBundle, new HashMap<String, String>());
 	}
 
 	@Test
-	public void testAddGet() {
+	void testAddGet() {
 		Service1 service1 = new Service1();
 		Service2 service2 = new Service2();
 		instance.add(Interf1.class, service1);
@@ -49,19 +50,12 @@ public void testAddGet() {
 	}
 
 	@Test
-	public void testMultipleServicesPerInterface() {
+	void testMultipleServicesPerInterface() {
 		Service1 serviceX = new Service1();
 		Service1 serviceY = new Service1();
 		instance.add(Interf1.class, serviceX);
-		boolean exceptionCaught = false;
-		try {
-			instance.add(Interf1.class, serviceY);
-		} catch (ServiceException e) {
-			exceptionCaught = true;
-			assertThat(e.getMessage()).as("ServiceException does not contain interface class name.").contains(Interf1.class.getName());
-		}
-		assertThat(exceptionCaught).as("No ServiceException thrown for duplicate interfaces.").isTrue();
-
+		ServiceException e = assertThrows(ServiceException.class, () -> instance.add(Interf1.class, serviceY));
+		assertThat(e.getMessage()).as("ServiceException does not contain interface class name.").contains(Interf1.class.getName());
 	}
 
 	private static class ServiceReferenceAssert extends AbstractAssert<ServiceReferenceAssert, ServiceCollection> {

_ext/eclipse-cdt/src/test/java/com/diffplug/spotless/extra/eclipse/cdt/EclipseCdtFormatterStepImplTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 DiffPlug
+ * Copyright 2016-2021 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,17 +16,17 @@
 package com.diffplug.spotless.extra.eclipse.cdt;
 
 import static com.diffplug.spotless.extra.eclipse.base.SpotlessEclipseFramework.LINE_DELIMITER;
-import static org.junit.Assert.*;
+import static org.junit.jupiter.api.Assertions.*;
 
 import java.util.Properties;
 import java.util.function.Consumer;
 
 import org.eclipse.cdt.core.CCorePlugin;
 import org.eclipse.cdt.core.formatter.DefaultCodeFormatterConstants;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /** Eclipse CDT wrapper integration tests */
-public class EclipseCdtFormatterStepImplTest {
+class EclipseCdtFormatterStepImplTest {
 
 	private final static String CPP_UNFORMATTED = "#include <iostream>\n" +
 			"using namespace std;\n" +
@@ -49,45 +49,45 @@ public class EclipseCdtFormatterStepImplTest {
 	private final static String FUNCT_PTR_FORMATTED = "void (* getFunc(void)) (int);";
 
 	@Test
-	public void defaultFormat() throws Throwable {
+	void defaultFormat() throws Throwable {
 		String output = format(CPP_UNFORMATTED, config -> {});
-		assertEquals("Unexpected formatting with default preferences.",
-				CPP_FORMATTED, output);
+		assertEquals(CPP_FORMATTED,
+				output, "Unexpected formatting with default preferences.");
 	}
 
 	@Test
-	public void invalidFormat() throws Throwable {
+	void invalidFormat() throws Throwable {
 		String output = format(CPP_FORMATTED.replace("int main() {", "int main()  "), config -> {});
-		assertTrue("Incomplete CPP not formatted on best effort basis.", output.contains("int main()" + LINE_DELIMITER));
+		assertTrue(output.contains("int main()" + LINE_DELIMITER), "Incomplete CPP not formatted on best effort basis.");
 	}
 
 	@Test
-	public void invalidCharater() throws Throwable {
+	void invalidCharater() throws Throwable {
 		String output = format(CPP_FORMATTED.replace("int main() {", "int main()" + ILLEGAL_CHAR + " {"), config -> {});
-		assertTrue("Invalid charater not formatted on best effort basis.", output.contains("int main()" + LINE_DELIMITER));
+		assertTrue(output.contains("int main()" + LINE_DELIMITER), "Invalid charater not formatted on best effort basis.");
 	}
 
 	@Test
-	public void invalidConfiguration() throws Throwable {
+	void invalidConfiguration() throws Throwable {
 		String output = format(CPP_FORMATTED, config -> {
 			config.setProperty(DefaultCodeFormatterConstants.FORMATTER_TAB_CHAR, CCorePlugin.SPACE);
 			config.setProperty(DefaultCodeFormatterConstants.FORMATTER_TAB_SIZE, "noInteger");
 		});
-		assertEquals("Invalid indentation configuration not replaced by default value (4 spaces)",
-				CPP_FORMATTED.replace("\t", "    "), output);
+		assertEquals(CPP_FORMATTED.replace("\t", "    "),
+				output, "Invalid indentation configuration not replaced by default value (4 spaces)");
 	}
 
 	@Test
-	public void htmlCommentFormat() throws Throwable {
+	void htmlCommentFormat() throws Throwable {
 		String output = format(DOXYGEN_HTML + CPP_FORMATTED, config -> {});
-		assertEquals("HTML comments not ignored by formatter.",
-				DOXYGEN_HTML + CPP_FORMATTED, output);
+		assertEquals(DOXYGEN_HTML + CPP_FORMATTED,
+				output, "HTML comments not ignored by formatter.");
 	}
 
 	@Test
-	public void regionWarning() throws Throwable {
+	void regionWarning() throws Throwable {
 		String output = format(FUNCT_PTR_UNFORMATTED, config -> {});
-		assertEquals("Code not formatted at all due to regional error.", FUNCT_PTR_FORMATTED, output);
+		assertEquals(FUNCT_PTR_FORMATTED, output, "Code not formatted at all due to regional error.");
 	}
 
 	private static String format(final String input, final Consumer<Properties> config) throws Exception {