StandardServletMultipartResolver provides strict Servlet compliance option

Closes gh-26826

spring-web/src/test/java/org/springframework/web/multipart/support/StandardServletMultipartResolverTests.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2002-2021 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
+ *
+ *      https://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.web.multipart.support;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.http.MediaType;
+import org.springframework.web.testfixture.servlet.MockHttpServletRequest;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Juergen Hoeller
+ */
+public class StandardServletMultipartResolverTests {
+
+	@Test
+	public void isMultipartWithDefaultSetting() {
+		StandardServletMultipartResolver resolver = new StandardServletMultipartResolver();
+
+		MockHttpServletRequest request = new MockHttpServletRequest("POST", "/");
+		assertThat(resolver.isMultipart(request)).isFalse();
+
+		request.setContentType(MediaType.MULTIPART_FORM_DATA_VALUE);
+		assertThat(resolver.isMultipart(request)).isTrue();
+
+		request.setContentType(MediaType.MULTIPART_MIXED_VALUE);
+		assertThat(resolver.isMultipart(request)).isTrue();
+
+		request.setContentType(MediaType.MULTIPART_RELATED_VALUE);
+		assertThat(resolver.isMultipart(request)).isTrue();
+
+		request = new MockHttpServletRequest("PUT", "/");
+		assertThat(resolver.isMultipart(request)).isFalse();
+
+		request.setContentType(MediaType.MULTIPART_FORM_DATA_VALUE);
+		assertThat(resolver.isMultipart(request)).isTrue();
+
+		request.setContentType(MediaType.MULTIPART_MIXED_VALUE);
+		assertThat(resolver.isMultipart(request)).isTrue();
+
+		request.setContentType(MediaType.MULTIPART_RELATED_VALUE);
+		assertThat(resolver.isMultipart(request)).isTrue();
+	}
+
+	@Test
+	public void isMultipartWithStrictSetting() {
+		StandardServletMultipartResolver resolver = new StandardServletMultipartResolver();
+		resolver.setStrictServletCompliance(true);
+
+		MockHttpServletRequest request = new MockHttpServletRequest("POST", "/");
+		assertThat(resolver.isMultipart(request)).isFalse();
+
+		request.setContentType(MediaType.MULTIPART_FORM_DATA_VALUE);
+		assertThat(resolver.isMultipart(request)).isTrue();
+
+		request.setContentType(MediaType.MULTIPART_MIXED_VALUE);
+		assertThat(resolver.isMultipart(request)).isFalse();
+
+		request.setContentType(MediaType.MULTIPART_RELATED_VALUE);
+		assertThat(resolver.isMultipart(request)).isFalse();
+
+		request = new MockHttpServletRequest("PUT", "/");
+		assertThat(resolver.isMultipart(request)).isFalse();
+
+		request.setContentType(MediaType.MULTIPART_FORM_DATA_VALUE);
+		assertThat(resolver.isMultipart(request)).isTrue();
+
+		request.setContentType(MediaType.MULTIPART_MIXED_VALUE);
+		assertThat(resolver.isMultipart(request)).isFalse();
+
+		request.setContentType(MediaType.MULTIPART_RELATED_VALUE);
+		assertThat(resolver.isMultipart(request)).isFalse();
+	}
+
+}