[test] add unit regarding the error handling

test/error-handle.test.js

@@ -0,0 +1,107 @@
+const fs = require('fs');
+const tts = require('..');
+const fetch = require('isomorphic-fetch');
+jest.setTimeout(60000);
+
+jest.mock('isomorphic-fetch');
+const host = 'https://translate.google.com';
+
+const html = {
+  hasTokenKey: fs.readFileSync(`${__dirname}/__mocks__/has-tkk.html`, 'utf8'),
+  noTokenKey: fs.readFileSync(`${__dirname}/__mocks__/no-tkk.html`, 'utf8'),
+};
+
+const mockResponse = {
+  htmlFailed: () => {
+    fetch.mockImplementationOnce(async (url) => {
+      if (url !== host) throw new Error('test failed');
+      return { status: 400, statusText: 'request failed' };
+    });
+  },
+  htmlSuccessWithTokenKey: () => {
+    fetch.mockImplementationOnce(async (url) => {
+      if (url !== host) throw new Error('test failed');
+      return { status: 200, text: async () => html.hasTokenKey };
+    });
+  },
+  htmlSuccessButNoTokenKey: () => {
+    fetch.mockImplementationOnce(async (url) => {
+      if (url !== host) throw new Error('text failed');
+      return { status: 200, text: async () => html.noTokenKey };
+    });
+  },
+  validateSucceed: () => {
+    fetch.mockImplementationOnce(async (url) => {
+      if (url === host) throw new Error('test failed');
+      return { status: 200 };
+    });
+  },
+  validateFailed: () => {
+    fetch.mockImplementationOnce(async (url) => {
+      if (url === host) throw new Error('test failed');
+      return { status: 400 };
+    });
+  },
+};
+
+describe('Google TTS', () => {
+  beforeEach(fetch.mockReset);
+
+  describe('first time using tts function', () => {
+    it('get html failed', async () => {
+      mockResponse.htmlFailed();
+      await expect(tts('hello')).rejects.toThrow('status code = 400');
+      expect(fetch).toHaveBeenCalledTimes(1);
+    });
+
+    it('cannot get the token key (retry 10 times)', async () => {
+      for (let i = 0; i < 10; i++) {
+        mockResponse.htmlSuccessButNoTokenKey();
+      }
+      await expect(tts('hello')).rejects.toThrow('get token key failed from google');
+      expect(fetch).toHaveBeenCalledTimes(10);
+    });
+
+    it('retry 3 times to get the token key', async () => {
+      mockResponse.htmlSuccessButNoTokenKey();
+      mockResponse.htmlSuccessButNoTokenKey();
+      mockResponse.htmlSuccessButNoTokenKey();
+      mockResponse.htmlSuccessWithTokenKey();
+
+      const url = await tts('hello');
+      expect(url).toBe(
+        'https://translate.google.com/translate_tts?ie=UTF-8&q=hello&tl=en&total=1&idx=0&textlen=5&tk=918197.577527&client=t&prev=input&ttsspeed=1'
+      );
+      expect(fetch).toHaveBeenCalledTimes(4);
+    });
+  });
+
+  describe('non-first time using tts function', () => {
+    it('validate success', async () => {
+      mockResponse.validateSucceed();
+      const url = await tts('test', 'en', 0.24);
+
+      expect(url).toBe(
+        'https://translate.google.com/translate_tts?ie=UTF-8&q=test&tl=en&total=1&idx=0&textlen=4&tk=376585.225867&client=t&prev=input&ttsspeed=0.24'
+      );
+      expect(fetch).toHaveBeenCalledTimes(1);
+    });
+
+    it('validate failed: retry 3 times to get the new token', async () => {
+      mockResponse.validateFailed();
+      mockResponse.htmlSuccessButNoTokenKey();
+      mockResponse.htmlSuccessButNoTokenKey();
+      mockResponse.htmlSuccessButNoTokenKey();
+      fetch.mockImplementationOnce(async (url) => {
+        if (url !== host) throw new Error('test failed');
+        return { status: 200, text: async () => "......tkk:'1234557.1234567'....." };
+      });
+
+      const url = await tts('test');
+      expect(url).toBe(
+        'https://translate.google.com/translate_tts?ie=UTF-8&q=test&tl=en&total=1&idx=0&textlen=4&tk=321164.1454321&client=t&prev=input&ttsspeed=1'
+      );
+      expect(fetch).toHaveBeenCalledTimes(5);
+    });
+  });
+});