Auto-exclude test components from scanning

Add TestTypeExcludeFilter which will automatically attempt to exclude
test only configurations. All `@Configuration` annotated inner-classes
of tests are automatically excluded. The `@TestConfiguration` annotation
can be used to explicitly if a configuration needs explicit exclusion.

See gh-5295
See gh-4901

spring-boot-test/src/test/java/org/springframework/boot/test/context/filter/SampleConfig.java

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2012-2016 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.boot.test.context.filter;
+
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class SampleConfig {
+
+}

spring-boot-test/src/test/java/org/springframework/boot/test/context/filter/SampleTestConfig.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2012-2016 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.boot.test.context.filter;
+
+import org.springframework.boot.test.context.TestComponent;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+@TestComponent
+public class SampleTestConfig {
+
+}

spring-boot-test/src/test/java/org/springframework/boot/test/context/filter/TestTypeExcludeFilterTests.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2012-2016 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.boot.test.context.filter;
+
+import java.io.IOException;
+
+import org.junit.Test;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.type.classreading.MetadataReader;
+import org.springframework.core.type.classreading.MetadataReaderFactory;
+import org.springframework.core.type.classreading.SimpleMetadataReaderFactory;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link TestTypeExcludeFilter}.
+ *
+ * @author Phillip Webb
+ */
+public class TestTypeExcludeFilterTests {
+
+	private TestTypeExcludeFilter filter = new TestTypeExcludeFilter();
+
+	private MetadataReaderFactory metadataReaderFactory = new SimpleMetadataReaderFactory();
+
+	@Test
+	public void matchesTestClass() throws Exception {
+		assertThat(this.filter.match(getMetadataReader(TestTypeExcludeFilterTests.class),
+				this.metadataReaderFactory)).isTrue();
+	}
+
+	@Test
+	public void matchesNestedConfiguration() throws Exception {
+		assertThat(this.filter.match(getMetadataReader(NestedConfig.class),
+				this.metadataReaderFactory)).isTrue();
+	}
+
+	@Test
+	public void matchesTestConfiguration() throws Exception {
+		assertThat(this.filter.match(getMetadataReader(SampleTestConfig.class),
+				this.metadataReaderFactory)).isTrue();
+	}
+
+	@Test
+	public void doesNotMatchRegularConfiguration() throws Exception {
+		assertThat(this.filter.match(getMetadataReader(SampleConfig.class),
+				this.metadataReaderFactory)).isFalse();
+	}
+
+	private MetadataReader getMetadataReader(Class<?> source) throws IOException {
+		return this.metadataReaderFactory.getMetadataReader(source.getName());
+	}
+
+	@Configuration
+	static class NestedConfig {
+
+	}
+
+}