SPR-16499 - MockHttpServletRequest.getReader vs. getInputStream

spring-test/src/main/java/org/springframework/mock/web/MockHttpServletRequest.java

@@ -175,6 +175,9 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	@Nullable
 	private byte[] content;
 
+	@Nullable
+	private ContentExtractMethod contentExtractMethod;
+
 	@Nullable
 	private String contentType;
 
@@ -492,6 +495,8 @@ public String getContentType() {
 
 	@Override
 	public ServletInputStream getInputStream() {
+		demandContentExtractMethod(ContentExtractMethod.INPUT_STREAM);
+
 		if (this.content != null) {
 			return new DelegatingServletInputStream(new ByteArrayInputStream(this.content));
 		}
@@ -697,6 +702,8 @@ public int getServerPort() {
 
 	@Override
 	public BufferedReader getReader() throws UnsupportedEncodingException {
+		demandContentExtractMethod(ContentExtractMethod.READER);
+
 		if (this.content != null) {
 			InputStream sourceStream = new ByteArrayInputStream(this.content);
 			Reader sourceReader = (this.characterEncoding != null) ?
@@ -709,6 +716,17 @@ public BufferedReader getReader() throws UnsupportedEncodingException {
 		}
 	}
 
+	private void demandContentExtractMethod(ContentExtractMethod methodToDemand) {
+		if (this.contentExtractMethod != null && 
+				!this.contentExtractMethod.equals(methodToDemand)) {
+			throw new IllegalStateException(
+					"Cannot call " + methodToDemand.methodName + "()" + 
+					" after " + this.contentExtractMethod.methodName + "()" + 
+					" has already been called for the current request");
+		}
+		this.contentExtractMethod = methodToDemand;
+	}
+
 	public void setRemoteAddr(String remoteAddr) {
 		this.remoteAddr = remoteAddr;
 	}
@@ -1345,4 +1363,15 @@ public <T extends HttpUpgradeHandler> T upgrade(Class<T> handlerClass) throws IO
 		throw new UnsupportedOperationException();
 	}
 
+
+	private enum ContentExtractMethod {
+		READER("getReader"), INPUT_STREAM("getInputStream");
+
+		final String methodName;
+
+		ContentExtractMethod(String methodName) {
+			this.methodName = methodName;
+		}
+	}
+
 }

spring-test/src/test/java/org/springframework/mock/web/MockHttpServletRequestTests.java

@@ -112,6 +112,34 @@ public void noContent() throws IOException {
 		assertNull(request.getContentAsByteArray());
 	}
 
+	@Test
+	public void getReaderAfterGettingInputStream() throws IOException {
+		exception.expect(IllegalStateException.class);
+		exception.expectMessage("Cannot call getReader() after" + 
+				" getInputStream() has already been called for the current request");
+		try {
+			request.getInputStream();
+		}
+		catch (IllegalStateException e) {
+			fail("Call to getInputStream() failed unexpectedly.");
+		}
+		request.getReader();
+	}
+
+	@Test
+	public void getInputStreamAfterGettingReader() throws IOException {
+		exception.expect(IllegalStateException.class);
+		exception.expectMessage("Cannot call getInputStream() after" + 
+				" getReader() has already been called for the current request");
+		try {
+			request.getReader();
+		}
+		catch (IllegalStateException e) {
+			fail("Call to getReader() failed unexpectedly.");
+		}
+		request.getInputStream();
+	}
+
 	@Test
 	public void setContentType() {
 		String contentType = "test/plain";