test(fixRequestBody): add unit test

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

@@ -0,0 +1,66 @@
+import { ClientRequest } from 'http';
+import * as querystring from 'querystring';
+
+import { fixRequestBody } from '../../src/handlers/fix-request-body';
+import type { Request } from '../../src/types';
+
+const fakeProxyRequest = () => {
+  const proxyRequest = new ClientRequest('http://some-host');
+  proxyRequest.emit = jest.fn();
+
+  return proxyRequest;
+};
+
+describe('fixRequestBody', () => {
+  it('should not write when body is undefined', () => {
+    const proxyRequest = fakeProxyRequest();
+
+    jest.spyOn(proxyRequest, 'setHeader');
+    jest.spyOn(proxyRequest, 'write');
+
+    fixRequestBody(proxyRequest, { body: undefined } as Request);
+
+    expect(proxyRequest.setHeader).not.toHaveBeenCalled();
+    expect(proxyRequest.write).not.toHaveBeenCalled();
+  });
+
+  it('should not write when body is empty', () => {
+    const proxyRequest = fakeProxyRequest();
+
+    jest.spyOn(proxyRequest, 'setHeader');
+    jest.spyOn(proxyRequest, 'write');
+
+    fixRequestBody(proxyRequest, { body: {} } as Request);
+
+    expect(proxyRequest.setHeader).not.toHaveBeenCalled();
+    expect(proxyRequest.write).not.toHaveBeenCalled();
+  });
+
+  it('should write when body is not empty and Content-Type is application/json', () => {
+    const proxyRequest = fakeProxyRequest();
+    proxyRequest.setHeader('content-type', 'application/json; charset=utf-8');
+
+    jest.spyOn(proxyRequest, 'setHeader');
+    jest.spyOn(proxyRequest, 'write');
+
+    fixRequestBody(proxyRequest, { body: { someField: 'some value' } } as Request);
+
+    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');
+
+    jest.spyOn(proxyRequest, 'setHeader');
+    jest.spyOn(proxyRequest, 'write');
+
+    fixRequestBody(proxyRequest, { body: { someField: 'some value' } } as Request);
+
+    const expectedBody = querystring.stringify({ someField: 'some value' });
+    expect(proxyRequest.setHeader).toHaveBeenCalledWith('Content-Length', expectedBody.length);
+    expect(proxyRequest.write).toHaveBeenCalledWith(expectedBody);
+  });
+});