Introduce 'spring-build-junit' subproject

Introduce new 'spring-build-junit' subproject containing shared
JUnit utilities and classes to be used by other test cases. This
project is for internal use within the framework, and therefore
creates no artifacts to be published to any repository.

The initial code includes support for JUnit Assumptions that can
be used to determine when a test should run. Tests can be skipped
based on the running JDK version, logging level or based on specific
'groups' that have activated via a Gradle property.

It is intended that sources within the spring-build-junit project be
folded into spring-core/src/test/java, pending some Gradle work that
will facilitate sharing test output across subprojects; therefore this
commit should be seen as a temporary solution.

Issue: SPR-9984

Author: philwebb

build.gradle

@@ -110,7 +110,7 @@ configure(allprojects.findAll{it.name in ["spring", "spring-jms", "spring-orm",
 	}
 }
 
-configure(subprojects) { subproject ->
+configure(subprojects - project(":spring-build-junit")) { subproject ->
 	apply plugin: "merge"
 	apply from: "${gradleScriptDir}/publish-maven.gradle"
 
@@ -159,6 +159,34 @@ configure(subprojects) { subproject ->
 	}
 }
 
+configure(allprojects - project(":spring-build-junit")) {
+	dependencies {
+		testCompile(project(":spring-build-junit"))
+	}
+
+	eclipse.classpath.file.whenMerged { classpath ->
+		classpath.entries.find{it.path == "/spring-build-junit"}.exported = false
+	}
+
+	test.systemProperties.put("testGroups", properties.get("testGroups"))
+}
+
+project("spring-build-junit") {
+	description = "Build-time JUnit dependencies and utilities"
+
+	// NOTE: This is an internal project and is not published.
+
+	dependencies {
+		compile("commons-logging:commons-logging:1.1.1")
+		compile("junit:junit:${junitVersion}")
+		compile("org.hamcrest:hamcrest-all:1.3")
+		compile("org.easymock:easymock:${easymockVersion}")
+	}
+
+	// Don't actually generate any artifacts
+	configurations.archives.artifacts.clear()
+}
+
 
 project("spring-core") {
 	description = "Spring Core"

settings.gradle

@@ -22,3 +22,4 @@ include "spring-web"
 include "spring-webmvc"
 include "spring-webmvc-portlet"
 include "spring-webmvc-tiles3"
+include "spring-build-junit"

spring-build-junit/src/main/java/org/springframework/build/junit/Assume.java

@@ -0,0 +1,111 @@
+/*
+ * Copyright 2002-2012 the original author or authors.
+ *
+ * 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 org.springframework.build.junit;
+
+import static org.junit.Assume.assumeFalse;
+
+import java.util.Set;
+
+import org.apache.commons.logging.Log;
+import org.junit.internal.AssumptionViolatedException;
+
+/**
+ * Provides utility methods that allow JUnit tests to {@link Assume} certain conditions
+ * hold {@code true}. If the assumption fails, it means the test should be skipped.
+ *
+ * <p>For example, if a set of tests require at least JDK 1.7 it can use
+ * {@code Assume#atLeast(JdkVersion.JAVA_17)} as shown below:
+ *
+ * <pre class="code">
+ * public void MyTests {
+ *
+ *   &#064;BeforeClass
+ *   public static assumptions() {
+ *       Assume.atLeast(JdkVersion.JAVA_17);
+ *   }
+ *
+ *   // ... all the test methods that require at least JDK 1.7
+ * }
+ * </pre>
+ *
+ * If only a single test requires at least JDK 1.7 it can use the
+ * {@code Assume#atLeast(JdkVersion.JAVA_17)} as shown below:
+ *
+ * <pre class="code">
+ * public void MyTests {
+ *
+ *   &#064;Test
+ *   public void requiresJdk17 {
+ *       Assume.atLeast(JdkVersion.JAVA_17);
+ *       // ... perform the actual test
+ *   }
+ * }
+ * </pre>
+ *
+ * In addition to assumptions based on the JDK version, tests can be categorized into
+ * {@link TestGroup}s. Active groups are enabled using the 'testGroups' system property,
+ * usually activated from the gradle command line:
+ * <pre>
+ * gradle test -PtestGroups="performance"
+ * </pre>
+ *
+ * Groups can be specified as a comma separated list of values, or using the pseudo group
+ * 'all'. See {@link TestGroup} for a list of valid groups.
+ *
+ * @author Rob Winch
+ * @author Phillip Webb
+ * @since 3.2
+ * @see #atLeast(JavaVersion)
+ * @see #group(TestGroup)
+ */
+public abstract class Assume {
+
+
+	private static final Set<TestGroup> GROUPS = TestGroup.parse(System.getProperty("testGroups"));
+
+
+	/**
+	 * Assume a minimum {@link JavaVersion} is running.
+	 * @param version the minimum version for the test to run
+	 */
+	public static void atLeast(JavaVersion version) {
+		if (!JavaVersion.runningVersion().isAtLeast(version)) {
+			throw new AssumptionViolatedException("Requires JDK " + version + " but running "
+					+ JavaVersion.runningVersion());
+		}
+	}
+
+	/**
+	 * Assume that a particular {@link TestGroup} has been specified.
+	 * @param group the group that must be specified.
+	 */
+	public static void group(TestGroup group) {
+		if (!GROUPS.contains(group)) {
+			throw new AssumptionViolatedException("Requires unspecified group " + group
+					+ " from " + GROUPS);
+		}
+	}
+
+	/**
+	 * Assume that the specified log is not set to Trace or Debug.
+	 * @param log the log to test
+	 */
+	public static void notLogging(Log log) {
+		assumeFalse(log.isTraceEnabled());
+		assumeFalse(log.isDebugEnabled());
+	}
+}

spring-build-junit/src/main/java/org/springframework/build/junit/JavaVersion.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright 2002-2012 the original author or authors.
+ *
+ * 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 org.springframework.build.junit;
+
+/**
+ * Enumeration of known JDK versions.
+ *
+ * @author Phillip Webb
+ * @see #runningVersion()
+ */
+public enum JavaVersion {
+
+
+	/**
+	 * Java 1.5
+	 */
+	JAVA_15("1.5", 15),
+
+	/**
+	 * Java 1.6
+	 */
+	JAVA_16("1.6", 16),
+
+	/**
+	 * Java 1.7
+	 */
+	JAVA_17("1.7", 17),
+
+	/**
+	 * Java 1.8
+	 */
+	JAVA_18("1.8", 18);
+
+
+	private static final JavaVersion runningVersion = findRunningVersion();
+
+	private static JavaVersion findRunningVersion() {
+		String version = System.getProperty("java.version");
+		for (JavaVersion candidate : values()) {
+			if (version.startsWith(candidate.version)) {
+				return candidate;
+			}
+		}
+		return JavaVersion.JAVA_15;
+	}
+
+
+	private String version;
+
+	private int value;
+
+
+	private JavaVersion(String version, int value) {
+		this.version = version;
+		this.value = value;
+	}
+
+
+	@Override
+	public String toString() {
+		return version;
+	}
+
+	/**
+	 * Determines if the specified version is the same as or greater than this version.
+	 * @param version the version to check
+	 * @return {@code true} if the specified version is at least this version
+	 */
+	public boolean isAtLeast(JavaVersion version) {
+		return this.value >= version.value;
+	}
+
+
+	/**
+	 * Returns the current running JDK version. If the current version cannot be
+	 * determined {@link #JAVA_15} will be returned.
+	 * @return the JDK version
+	 */
+	public static JavaVersion runningVersion() {
+		return runningVersion;
+	}
+}

spring-build-junit/src/main/java/org/springframework/build/junit/TestGroup.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2002-2012 the original author or authors.
+ *
+ * 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 org.springframework.build.junit;
+
+import java.util.Collections;
+import java.util.EnumSet;
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * A test group used to limit when certain tests are run.
+ *
+ * @see Assume#group(TestGroup)
+ * @author Phillip Webb
+ */
+public enum TestGroup {
+
+
+	/**
+	 * Performance related tests that may take a considerable time to run.
+	 */
+	PERFORMANCE;
+
+
+	/**
+	 * Parse the specified comma separates string of groups.
+	 * @param value the comma separated string of groups
+	 * @return a set of groups
+	 */
+	public static Set<TestGroup> parse(String value) {
+		if (value == null || "".equals(value)) {
+			return Collections.emptySet();
+		}
+		if("ALL".equalsIgnoreCase(value)) {
+			return EnumSet.allOf(TestGroup.class);
+		}
+		Set<TestGroup> groups = new HashSet<TestGroup>();
+		for (String group : value.split(",")) {
+			try {
+				groups.add(valueOf(group.trim().toUpperCase()));
+			} catch (IllegalArgumentException e) {
+				throw new IllegalArgumentException("Unable to find test group '" + group.trim()
+						+ "' when parsing '" + value + "'");
+			}
+		}
+		return groups;
+	}
+}

spring-build-junit/src/test/java/org/springframework/build/junit/JavaVersionTest.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2002-2012 the original author or authors.
+ *
+ * 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 org.springframework.build.junit;
+
+import static org.hamcrest.Matchers.startsWith;
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+/**
+ * Tests for {@link JavaVersion}.
+ *
+ * @author Phillip Webb
+ */
+public class JavaVersionTest {
+
+	@Test
+	public void runningVersion() {
+		assertNotNull(JavaVersion.runningVersion());
+		assertThat(System.getProperty("java.version"), startsWith(JavaVersion.runningVersion().toString()));
+	}
+
+	@Test
+	public void isAtLeast() throws Exception {
+		assertTrue(JavaVersion.JAVA_16.isAtLeast(JavaVersion.JAVA_15));
+		assertTrue(JavaVersion.JAVA_16.isAtLeast(JavaVersion.JAVA_16));
+		assertFalse(JavaVersion.JAVA_16.isAtLeast(JavaVersion.JAVA_17));
+	}
+}