Fix/singleton test (#9)

* start of singleton test fix

* works again

* some polish for singleton tests

* complete note

* fix linter stuff

Author: rlindner81

test/__common__/ftProps.js

@@ -0,0 +1,25 @@
+"use strict";
+
+const { FeatureToggles } = jest.requireActual("../../src/featureToggles");
+const singleton = jest.requireActual("../../src/singleton");
+
+const IGNORE_PROPERTIES = ["constructor", "length", "name", "prototype", "getInstance"];
+
+const ftInstanceProps = Object.getOwnPropertyNames(FeatureToggles.prototype).filter(
+  (prop) => !IGNORE_PROPERTIES.includes(prop) && !prop.startsWith("_")
+);
+const ftClassProps = Object.getOwnPropertyNames(FeatureToggles).filter(
+  (prop) => !IGNORE_PROPERTIES.includes(prop) && !prop.startsWith("_")
+);
+const ftProps = [].concat(ftClassProps, ftInstanceProps);
+
+const singletonProps = Object.keys(singleton).filter((p) => !p.startsWith("_"));
+
+module.exports = {
+  IGNORE_PROPERTIES,
+
+  ftInstanceProps,
+  ftClassProps,
+  ftProps,
+  singletonProps,
+};

test/singleton.test.js

@@ -1,30 +1,17 @@
 "use strict";
 
-const { FeatureToggles } = require("../src/featureToggles");
-const singleton = require("../src/singleton");
 const { ENV } = require("../src/shared/static");
 
 describe("singleton test", () => {
   beforeEach(() => {
     jest.clearAllMocks();
   });
 
-  it("singleton correctly exposes public apis of feature-toggles", async () => {
-    const IGNORE_PROPERTIES = ["constructor", "length", "name", "prototype", "getInstance"];
-
-    // check same properties
-    const singletonProps = Object.keys(singleton).filter((p) => !p.startsWith("_"));
-    const ftInstanceProps = Object.getOwnPropertyNames(FeatureToggles.prototype).filter(
-      (prop) => prop !== "constructor" && !prop.startsWith("_")
-    );
-    const ftClassProps = Object.getOwnPropertyNames(FeatureToggles).filter(
-      (prop) => !IGNORE_PROPERTIES.includes(prop) && !prop.startsWith("_")
-    );
-    const ftProps = [].concat(ftClassProps, ftInstanceProps);
+  it("singleton exposes same public apis as feature-toggles", async () => {
+    const { ftProps, singletonProps } = require("./__common__/ftProps");
 
     const sameLength = ftProps.length === singletonProps.length;
     const mismatch = ftProps.find((p, i) => p !== singletonProps[i]);
-
     expect(sameLength).toBe(true);
     expect(mismatch).toBe(undefined);
   });

test/singletonWithMock.test.js

@@ -0,0 +1,40 @@
+"use strict";
+
+const MockFeatureToggles = jest.fn();
+jest.mock("../src/featureToggles", () => {
+  const { ftInstanceProps, ftClassProps } = require("./__common__/ftProps");
+  ftInstanceProps.forEach((prop) => {
+    MockFeatureToggles.prototype[prop] = jest.fn();
+  });
+  ftClassProps.forEach((prop) => {
+    MockFeatureToggles[prop] = jest.fn();
+  });
+  let instance = new MockFeatureToggles();
+  MockFeatureToggles.getInstance = () => instance;
+  return {
+    FeatureToggles: MockFeatureToggles,
+  };
+});
+const singleton = require("../src/singleton");
+
+describe("singleton test with feature toggles class mock", () => {
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  it("singleton property mapping is correct", async () => {
+    // NOTE: the singleton and FeatureToggles functions match up, but the mapping could be flipped, so we check that
+    //   any call to the singleton reaches the correct instance function of the FeatureToggles
+    const { singletonProps } = require("./__common__/ftProps");
+
+    const inputs = ["input1", "input2"];
+    const instance = MockFeatureToggles.getInstance();
+    for (const prop of singletonProps) {
+      const singletonFunc = singleton[prop];
+      const instanceFunc = instance[prop] || MockFeatureToggles[prop];
+      await singletonFunc(...inputs);
+      expect(instanceFunc).toHaveBeenCalledTimes(1);
+      expect(instanceFunc).toHaveBeenCalledWith(...inputs);
+    }
+  });
+});