test(ContentTypeMiddleware): add tests

src/middlewares/ContentTypeMiddleware.spec.ts

@@ -0,0 +1,21 @@
+import {ContentTypeMiddleware} from "./ContentTypeMiddleware";
+import {IFetchRequest} from "./FetchMiddleware";
+
+describe("ContentTypeMiddleware", () => {
+    it("should add a content type application/json by default", () => {
+        const spy = jest.fn((options: IFetchRequest) => {
+            const contentType = options.headers && options.headers["content-type"];
+            expect(contentType).toBe("application/json");
+        });
+        const mw = new ContentTypeMiddleware();
+        mw.process({}, spy);
+    });
+    it("should accept a content type in constructor if we want to change it", () => {
+        const spy = jest.fn((options: IFetchRequest) => {
+            const contentType = options.headers && options.headers["content-type"];
+            expect(contentType).toBe("text/plain");
+        });
+        const mw = new ContentTypeMiddleware("text/plain");
+        mw.process({}, spy);
+    });
+});