Support expressing application args in @SpringBootTest

Add `args` property to the `@SpringBootTest` annotation so tests
can easily supply application arguments to pass to their app under test.

See gh-14823

spring-boot-project/spring-boot-test/src/test/java/org/springframework/boot/test/context/SpringBootTestArgsTests.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2012-2017 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;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.ApplicationArguments;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Assert that tests annotated with {@link SpringBootTest} can specify
+ * {@link SpringBootTest#args()} to be passed to their application under test.
+ *
+ * @author Justin Griffin
+ */
+@RunWith(SpringRunner.class)
+@SpringBootTest(args = { "--option.foo=option-foo-value", "other.bar=other-bar-value" })
+public class SpringBootTestArgsTests {
+
+	@Autowired
+	private ApplicationArguments args;
+
+	@Test
+	public void applicationArgumentsPopulated() {
+		assertThat(this.args.getOptionNames()).contains("option.foo");
+		assertThat(this.args.getNonOptionArgs()).contains("other.bar=other-bar-value");
+	}
+
+	@Configuration
+	protected static class Config {
+
+	}
+
+}