tests: write unit tests

__mocks__/request-helper.js

@@ -0,0 +1,12 @@
+const translationMap = require('./translationMap');
+
+module.exports = (options, postBody) => {
+  return new Promise((resolve, reject) => {
+    const { params: { jobs: [{ raw_en_sentence: inputText }] } } = postBody;
+
+    process.nextTick(
+      () =>
+        !translationMap[inputText] ? reject(new Error('This input should throw')) : resolve(translationMap[inputText])
+    );
+  });
+};

__mocks__/translationMap.js

@@ -0,0 +1,37 @@
+module.exports = {
+  'Happy birthday!': {
+    result: {
+      source_lang: 'EN',
+      target_lang: 'DE',
+      translations: [
+        {
+          beams: [
+            {
+              postprocessed_sentence: 'Herzlichen Glückwunsch zum Geburtstag!',
+            },
+          ],
+        },
+      ],
+    },
+  },
+  'This is a representative chunk of text in english.': {
+    result: {
+      source_lang: 'EN',
+      target_lang: 'DE',
+      translations: [
+        {
+          beams: [
+            {
+              postprocessed_sentence: 'This is a representative chunk of text in english.',
+            },
+          ],
+        },
+      ],
+    },
+  },
+  'This mock results in an incorrect reponse format': {
+    result: {
+      no_translations_here: [],
+    },
+  },
+};

__tests__/index.test.js

@@ -0,0 +1,42 @@
+jest.mock('../request-helper');
+
+const { translate, detectLanguage } = require('../index');
+
+test('Detects english input language correctly', () => {
+  return expect(detectLanguage('This is a representative chunk of text in english.')).resolves.toEqual({
+    languageCode: 'EN',
+    languageName: 'English',
+  });
+});
+
+test('Translate input correctly without specifying its language', () => {
+  return expect(translate('Happy birthday!', 'DE')).resolves.toEqual({
+    targetLanguage: 'DE',
+    resolvedSourceLanguage: 'EN',
+    translation: 'Herzlichen Glückwunsch zum Geburtstag!',
+  });
+});
+
+test('Rejects on invalid target language', () => {
+  return expect(translate('Happy birthday!')).rejects.toEqual(new Error('Invalid target language code undefined'));
+});
+
+test('Rejects on invalid source language', () => {
+  return expect(translate('Happy birthday!', 'DE', 'XX')).rejects.toEqual(new Error('Invalid source language code XX'));
+});
+
+test('Rejects when source and target languages are identical', () => {
+  return expect(translate('Happy birthday!', 'DE', 'DE')).rejects.toEqual(
+    new Error('Target and source language codes identical')
+  );
+});
+
+test('Rejects when input text is not provided', () => {
+  return expect(translate('', 'DE')).rejects.toEqual(new Error('Must provide text for translation'));
+});
+
+test('Rejects when response in incorrect format', () => {
+  return expect(translate('This mock results in an incorrect reponse format', 'DE')).rejects.toEqual(
+    new Error('Unexpected error when parsing response body: {"result":{"no_translations_here":[]}}')
+  );
+});

package.json

@@ -4,6 +4,13 @@
   "description":
     "This module provides promised methods for translating text using DeepL Translator (https://www.deepl.com/translator) undocumented API.",
   "main": "index.js",
+  "scripts": {
+    "test": "jest",
+    "collectCoverage": "true"
+  },
+  "jest": {
+    "verbose": true
+  },
   "repository": "https://github.com/vsetka/deepl-translator.git",
   "homepage": "https://github.com/vsetka/deepl-translator#readme",
   "author": "Vladimir Setka <vsetka@gmail.com>",
@@ -15,5 +22,9 @@
   "engineStrict": true,
   "engines": {
     "node": ">=6.0.0"
+  },
+  "devDependencies": {
+    "coveralls": "^2.13.1",
+    "jest": "^21.0.2"
   }
 }