Add nullability annotations to tests in module/spring-boot-servlet

See gh-47263

module/spring-boot-servlet/build.gradle

@@ -47,3 +47,7 @@ dependencies {
 tasks.named("test") {
 	jvmArgs += "--add-opens=java.base/java.net=ALL-UNNAMED"
 }
+
+tasks.named("compileTestJava") {
+	options.nullability.checking = "tests"
+}

module/spring-boot-servlet/src/test/java/org/springframework/boot/servlet/autoconfigure/HttpEncodingAutoConfigurationTests.java

@@ -20,6 +20,7 @@ import java.util.ArrayList;
 import java.util.List;
 
 import jakarta.servlet.Filter;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 
@@ -45,7 +46,7 @@ import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
  */
 class HttpEncodingAutoConfigurationTests {
 
-	private AnnotationConfigServletWebApplicationContext context;
+	private @Nullable AnnotationConfigServletWebApplicationContext context;
 
 	@AfterEach
 	void close() {
@@ -56,68 +57,71 @@ class HttpEncodingAutoConfigurationTests {
 
 	@Test
 	void defaultConfiguration() {
-		load(EmptyConfiguration.class);
-		CharacterEncodingFilter filter = this.context.getBean(CharacterEncodingFilter.class);
+		AnnotationConfigServletWebApplicationContext context = load(EmptyConfiguration.class);
+		CharacterEncodingFilter filter = context.getBean(CharacterEncodingFilter.class);
 		assertCharacterEncodingFilter(filter, "UTF-8", true, false);
 	}
 
 	@Test
 	void disableConfiguration() {
-		load(EmptyConfiguration.class, "spring.servlet.encoding.enabled:false");
+		AnnotationConfigServletWebApplicationContext context = load(EmptyConfiguration.class,
+				"spring.servlet.encoding.enabled:false");
 		assertThatExceptionOfType(NoSuchBeanDefinitionException.class)
-			.isThrownBy(() -> this.context.getBean(CharacterEncodingFilter.class));
+			.isThrownBy(() -> context.getBean(CharacterEncodingFilter.class));
 	}
 
 	@Test
 	void customConfiguration() {
-		load(EmptyConfiguration.class, "spring.servlet.encoding.charset:ISO-8859-15",
-				"spring.servlet.encoding.force:false");
-		CharacterEncodingFilter filter = this.context.getBean(CharacterEncodingFilter.class);
+		AnnotationConfigServletWebApplicationContext context = load(EmptyConfiguration.class,
+				"spring.servlet.encoding.charset:ISO-8859-15", "spring.servlet.encoding.force:false");
+		CharacterEncodingFilter filter = context.getBean(CharacterEncodingFilter.class);
 		assertCharacterEncodingFilter(filter, "ISO-8859-15", false, false);
 	}
 
 	@Test
 	void customFilterConfiguration() {
-		load(FilterConfiguration.class, "spring.servlet.encoding.charset:ISO-8859-15",
-				"spring.servlet.encoding.force:false");
-		CharacterEncodingFilter filter = this.context.getBean(CharacterEncodingFilter.class);
+		AnnotationConfigServletWebApplicationContext context = load(FilterConfiguration.class,
+				"spring.servlet.encoding.charset:ISO-8859-15", "spring.servlet.encoding.force:false");
+		CharacterEncodingFilter filter = context.getBean(CharacterEncodingFilter.class);
 		assertCharacterEncodingFilter(filter, "US-ASCII", false, false);
 	}
 
 	@Test
 	void forceRequest() {
-		load(EmptyConfiguration.class, "spring.servlet.encoding.force-request:false");
-		CharacterEncodingFilter filter = this.context.getBean(CharacterEncodingFilter.class);
+		AnnotationConfigServletWebApplicationContext context = load(EmptyConfiguration.class,
+				"spring.servlet.encoding.force-request:false");
+		CharacterEncodingFilter filter = context.getBean(CharacterEncodingFilter.class);
 		assertCharacterEncodingFilter(filter, "UTF-8", false, false);
 	}
 
 	@Test
 	void forceResponse() {
-		load(EmptyConfiguration.class, "spring.servlet.encoding.force-response:true");
-		CharacterEncodingFilter filter = this.context.getBean(CharacterEncodingFilter.class);
+		AnnotationConfigServletWebApplicationContext context = load(EmptyConfiguration.class,
+				"spring.servlet.encoding.force-response:true");
+		CharacterEncodingFilter filter = context.getBean(CharacterEncodingFilter.class);
 		assertCharacterEncodingFilter(filter, "UTF-8", true, true);
 	}
 
 	@Test
 	void forceRequestOverridesForce() {
-		load(EmptyConfiguration.class, "spring.servlet.encoding.force:true",
-				"spring.servlet.encoding.force-request:false");
-		CharacterEncodingFilter filter = this.context.getBean(CharacterEncodingFilter.class);
+		AnnotationConfigServletWebApplicationContext context = load(EmptyConfiguration.class,
+				"spring.servlet.encoding.force:true", "spring.servlet.encoding.force-request:false");
+		CharacterEncodingFilter filter = context.getBean(CharacterEncodingFilter.class);
 		assertCharacterEncodingFilter(filter, "UTF-8", false, true);
 	}
 
 	@Test
 	void forceResponseOverridesForce() {
-		load(EmptyConfiguration.class, "spring.servlet.encoding.force:true",
-				"spring.servlet.encoding.force-response:false");
-		CharacterEncodingFilter filter = this.context.getBean(CharacterEncodingFilter.class);
+		AnnotationConfigServletWebApplicationContext context = load(EmptyConfiguration.class,
+				"spring.servlet.encoding.force:true", "spring.servlet.encoding.force-response:false");
+		CharacterEncodingFilter filter = context.getBean(CharacterEncodingFilter.class);
 		assertCharacterEncodingFilter(filter, "UTF-8", true, false);
 	}
 
 	@Test
 	void filterIsOrderedHighest() {
-		load(OrderedConfiguration.class);
-		List<Filter> beans = new ArrayList<>(this.context.getBeansOfType(Filter.class).values());
+		AnnotationConfigServletWebApplicationContext context = load(OrderedConfiguration.class);
+		List<Filter> beans = new ArrayList<>(context.getBeansOfType(Filter.class).values());
 		AnnotationAwareOrderComparator.sort(beans);
 		assertThat(beans.get(0)).isInstanceOf(CharacterEncodingFilter.class);
 		assertThat(beans.get(1)).isInstanceOf(HiddenHttpMethodFilter.class);
@@ -130,8 +134,9 @@ class HttpEncodingAutoConfigurationTests {
 		assertThat(actual.isForceResponseEncoding()).isEqualTo(forceResponseEncoding);
 	}
 
-	private void load(Class<?> config, String... environment) {
+	private AnnotationConfigServletWebApplicationContext load(Class<?> config, String... environment) {
 		this.context = doLoad(new Class<?>[] { config }, environment);
+		return this.context;
 	}
 
 	private AnnotationConfigServletWebApplicationContext doLoad(Class<?>[] configs, String... environment) {

module/spring-boot-servlet/src/test/java/org/springframework/boot/servlet/autoconfigure/MultipartAutoConfigurationTests.java

@@ -20,6 +20,7 @@ import java.net.URI;
 import java.util.stream.Stream;
 
 import jakarta.servlet.MultipartConfigElement;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
@@ -33,6 +34,7 @@ import org.springframework.boot.testsupport.classpath.ForkedClassPath;
 import org.springframework.boot.testsupport.web.servlet.DirtiesUrlFactories;
 import org.springframework.boot.tomcat.autoconfigure.servlet.TomcatServletWebServerAutoConfiguration;
 import org.springframework.boot.tomcat.servlet.TomcatServletWebServerFactory;
+import org.springframework.boot.web.server.WebServer;
 import org.springframework.boot.web.server.autoconfigure.ServerProperties;
 import org.springframework.boot.web.server.servlet.context.AnnotationConfigServletWebServerApplicationContext;
 import org.springframework.context.annotation.Bean;
@@ -69,7 +71,7 @@ import static org.mockito.Mockito.mock;
 @DirtiesUrlFactories
 class MultipartAutoConfigurationTests {
 
-	private AnnotationConfigServletWebServerApplicationContext context;
+	private @Nullable AnnotationConfigServletWebServerApplicationContext context;
 
 	@AfterEach
 	void close() {
@@ -83,7 +85,7 @@ class MultipartAutoConfigurationTests {
 		this.context = new AnnotationConfigServletWebServerApplicationContext(WebServerWithNothing.class,
 				BaseConfiguration.class);
 		DispatcherServlet servlet = this.context.getBean(DispatcherServlet.class);
-		verify404();
+		verify404(this.context);
 		assertThat(servlet.getMultipartResolver()).isNotNull();
 		assertThat(this.context.getBeansOfType(StandardServletMultipartResolver.class)).hasSize(1);
 		assertThat(this.context.getBeansOfType(MultipartResolver.class)).hasSize(1);
@@ -96,7 +98,7 @@ class MultipartAutoConfigurationTests {
 		this.context = new AnnotationConfigServletWebServerApplicationContext(configuration, BaseConfiguration.class);
 		assertThat(this.context.getBeansOfType(StandardServletMultipartResolver.class)).hasSize(1);
 		assertThat(this.context.getBeansOfType(MultipartResolver.class)).hasSize(1);
-		verifyServletWorks();
+		verifyServletWorks(this.context);
 		assertThat(this.context.getBean(StandardServletMultipartResolver.class))
 			.isSameAs(this.context.getBean(DispatcherServlet.class).getMultipartResolver());
 	}
@@ -112,7 +114,7 @@ class MultipartAutoConfigurationTests {
 	void webServerWithAutomatedMultipartConfiguration(String server, Class<?> configuration) {
 		this.context = new AnnotationConfigServletWebServerApplicationContext(configuration, BaseConfiguration.class);
 		this.context.getBean(MultipartConfigElement.class);
-		verifyServletWorks();
+		verifyServletWorks(this.context);
 		assertThat(this.context.getBean(StandardServletMultipartResolver.class))
 			.isSameAs(this.context.getBean(DispatcherServlet.class).getMultipartResolver());
 	}
@@ -200,18 +202,22 @@ class MultipartAutoConfigurationTests {
 		assertThat(multipartConfigElement.getMaxRequestSize()).isEqualTo(2048);
 	}
 
-	private void verify404() throws Exception {
+	private void verify404(AnnotationConfigServletWebServerApplicationContext context) throws Exception {
 		HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();
+		WebServer webServer = context.getWebServer();
+		assertThat(webServer).isNotNull();
 		ClientHttpRequest request = requestFactory
-			.createRequest(new URI("http://localhost:" + this.context.getWebServer().getPort() + "/"), HttpMethod.GET);
+			.createRequest(new URI("http://localhost:" + webServer.getPort() + "/"), HttpMethod.GET);
 		try (ClientHttpResponse response = request.execute()) {
 			assertThat(response.getStatusCode()).isEqualTo(HttpStatus.NOT_FOUND);
 		}
 	}
 
-	private void verifyServletWorks() {
+	private void verifyServletWorks(AnnotationConfigServletWebServerApplicationContext context) {
 		RestTemplate restTemplate = new RestTemplate();
-		String url = "http://localhost:" + this.context.getWebServer().getPort() + "/";
+		WebServer webServer = context.getWebServer();
+		assertThat(webServer).isNotNull();
+		String url = "http://localhost:" + webServer.getPort() + "/";
 		assertThat(restTemplate.getForObject(url, String.class)).isEqualTo("Hello");
 	}