fix(fix-request-body): support '+json' content-type suffix

CHANGELOG.md

@@ -8,6 +8,7 @@
 - ci(package): npm package provenance
 - fix(logger-plugin): log target port when router option is used
 - refactor: fix circular dependencies
+- fix(fix-request-body): support '+json' content-type suffix
 
 ## [v3.0.0](https://github.com/chimurai/http-proxy-middleware/releases/tag/v3.0.0)
 

src/handlers/fix-request-body.ts

@@ -23,7 +23,7 @@ export function fixRequestBody<TReq = http.IncomingMessage>(
     proxyReq.write(bodyData);
   };
 
-  if (contentType && contentType.includes('application/json')) {
+  if (contentType && (contentType.includes('application/json') || contentType.includes('+json'))) {
     writeBody(JSON.stringify(requestBody));
   }
 

test/unit/fix-request-body.spec.ts

@@ -57,6 +57,20 @@ describe('fixRequestBody', () => {
     expect(proxyRequest.write).toHaveBeenCalledWith(expectedBody);
   });
 
+  it('should write when body is not empty and Content-Type ends with +json', () => {
+    const proxyRequest = fakeProxyRequest();
+    proxyRequest.setHeader('content-type', 'application/merge-patch+json; charset=utf-8');
+
+    jest.spyOn(proxyRequest, 'setHeader');
+    jest.spyOn(proxyRequest, 'write');
+
+    fixRequestBody(proxyRequest, createRequestWithBody({ someField: 'some value' }));
+
+    const expectedBody = JSON.stringify({ someField: 'some value' });
+    expect(proxyRequest.setHeader).toHaveBeenCalledWith('Content-Length', expectedBody.length);
+    expect(proxyRequest.write).toHaveBeenCalledWith(expectedBody);
+  });
+
   it('should write when body is not empty and Content-Type is application/x-www-form-urlencoded', () => {
     const proxyRequest = fakeProxyRequest();
     proxyRequest.setHeader('content-type', 'application/x-www-form-urlencoded');