Provide better names for the test plan specification

- Reduced dependencies to the Builder DSL

Issue: #116

junit-console/src/main/java/org/junit/gen5/console/tasks/DiscoveryRequestCreator.java

@@ -11,7 +11,6 @@
 package org.junit.gen5.console.tasks;
 
 import static java.util.stream.Collectors.toSet;
-import static org.junit.gen5.engine.discoveryrequest.dsl.ClassFilters.classNameMatches;
 import static org.junit.gen5.engine.discoveryrequest.dsl.ClasspathSelectorBuilder.byPaths;
 import static org.junit.gen5.engine.discoveryrequest.dsl.DiscoveryRequestBuilder.request;
 import static org.junit.gen5.engine.discoveryrequest.dsl.NameBasedSelectorBuilder.byNames;
@@ -23,6 +22,7 @@
 import org.junit.gen5.commons.util.ReflectionUtils;
 import org.junit.gen5.console.options.CommandLineOptions;
 import org.junit.gen5.engine.DiscoveryRequest;
+import org.junit.gen5.engine.discoveryrequest.dsl.ClassFilterBuilder;
 import org.junit.gen5.engine.discoveryrequest.dsl.TagFilterBuilder;
 
 class DiscoveryRequestCreator {
@@ -57,7 +57,7 @@ private DiscoveryRequest buildNameBasedDiscoveryRequest(CommandLineOptions optio
 	}
 
 	private void applyFilters(DiscoveryRequest discoveryRequest, CommandLineOptions options) {
-		options.getClassnameFilter().ifPresent(regex -> discoveryRequest.addFilter(classNameMatches(regex)));
+		options.getClassnameFilter().ifPresent(regex -> discoveryRequest.addFilter(ClassFilterBuilder.pattern(regex)));
 		if (!options.getTagsFilter().isEmpty()) {
 			discoveryRequest.addPostFilter(TagFilterBuilder.includeTags(options.getTagsFilter()));
 		}

junit-engine-api/src/main/java/org/junit/gen5/engine/discoveryrequest/dsl/ClassFilterBuilder.java

@@ -10,9 +10,15 @@
 
 package org.junit.gen5.engine.discoveryrequest.dsl;
 
+import org.junit.gen5.engine.ClassFilter;
+import org.junit.gen5.engine.FilterResult;
 import org.junit.gen5.engine.discoveryrequest.ClassNameFilter;
 
 public class ClassFilterBuilder {
+	public static ClassFilter anyClass() {
+		return testClass -> FilterResult.included("Any class");
+	}
+
 	public static ClassNameFilter pattern(String pattern) {
 		return new ClassNameFilter(pattern);
 	}

junit-engine-api/src/main/java/org/junit/gen5/engine/discoveryrequest/dsl/CommonBuilder.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2015-2016 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v1.0 which
+ * accompanies this distribution and is available at
+ *
+ * http://www.eclipse.org/legal/epl-v10.html
+ */
+
+package org.junit.gen5.engine.discoveryrequest.dsl;
+
+import static java.lang.String.format;
+import static java.util.Arrays.asList;
+import static java.util.stream.Collectors.joining;
+
+import java.util.Collection;
+import java.util.StringJoiner;
+import java.util.stream.Collectors;
+
+import org.junit.gen5.engine.DiscoveryFilter;
+import org.junit.gen5.engine.DiscoveryRequest;
+import org.junit.gen5.engine.FilterResult;
+
+/**
+ * A collection of common builders for {@link DiscoveryRequest} elements.
+ *
+ * @since 5.0
+ */
+public class CommonBuilder {
+	public static <T> DiscoveryFilter<T> alwaysIncluded() {
+		return (any) -> FilterResult.included("Always included");
+	}
+
+	public static <T> DiscoveryFilter<T> alwaysExcluded() {
+		return (any) -> FilterResult.excluded("Always excluded");
+	}
+
+	public static <T> DiscoveryFilter<T> allOf(DiscoveryFilter<T>... filters) {
+		if (filters == null) {
+			return alwaysIncluded();
+		}
+		else {
+			return allOf(asList(filters));
+		}
+	}
+
+	public static <T> DiscoveryFilter<T> allOf(Collection<DiscoveryFilter<T>> filters) {
+		if (filters == null || filters.isEmpty()) {
+			return alwaysIncluded();
+		}
+		else if (filters.size() == 1) {
+			return filters.iterator().next();
+		}
+		else {
+			return new AndAllDiscoveryFilter(filters);
+		}
+	}
+
+	private static class AndAllDiscoveryFilter<T> implements DiscoveryFilter<T> {
+		private final Collection<DiscoveryFilter<T>> filters;
+
+		public AndAllDiscoveryFilter(Collection<DiscoveryFilter<T>> filters) {
+			this.filters = filters;
+		}
+
+		@Override
+		public FilterResult filter(T element) {
+			// @formatter:off
+            return this.filters.stream()
+                    .map(filter -> filter.filter(element))
+                    .filter(FilterResult::excluded)
+                    .findFirst()
+                    .orElse(FilterResult.included("Element was included by all filters."));
+            // @formatter:on
+		}
+
+		@Override
+		public String toString() {
+			return this.filters.stream().map(Object::toString).map(s -> format("(%s)", s)).collect(joining(" and "));
+		}
+	}
+}

junit-tests/src/test/java/org/junit/gen5/engine/ClassFilterBuilderTests.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2015-2016 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v1.0 which
+ * accompanies this distribution and is available at
+ *
+ * http://www.eclipse.org/legal/epl-v10.html
+ */
+
+package org.junit.gen5.engine;
+
+import static org.junit.gen5.api.Assertions.*;
+
+import java.util.Collection;
+
+import org.junit.gen5.api.Test;
+import org.junit.gen5.engine.discoveryrequest.dsl.ClassFilterBuilder;
+
+class ClassFilterBuilderTests {
+	@Test
+	void classNameMatches() {
+		String regex = "^java\\.lang\\..*";
+
+		ClassFilter filter = ClassFilterBuilder.pattern(regex);
+
+		assertEquals("Filter class names with regular expression: " + regex, filter.toString());
+		assertTrue(filter.filter(String.class).included());
+		assertFalse(filter.filter(Collection.class).included());
+	}
+
+	@Test
+	void anyClass() {
+		ClassFilter filter = ClassFilterBuilder.anyClass();
+
+		assertTrue(filter.filter(String.class).included());
+		assertTrue(filter.filter(this.getClass()).included());
+	}
+}