Fix flow types and enable flow types testing on CI (#896)

* Fix broken unit tests

The tests were using "assert" function wrong.
"assert" is defined as: assert(value, [message])

The tests passed two arguments in an attempt to compare them while
the only thing that happened was that the first value was checked for
being truthy.

* Fix flow types and enable flow testing on CI

Types fixed by making "getChoiceIndex" method follow types and be
a class property rather than class method. Class methods are "read-only"
in flow and that wasn't compatible with flow types that are defining
that function as a property (to allow overriding through prototype changing).

.circleci/config.yml

@@ -41,7 +41,10 @@ jobs:
       - run:
           name: Lint
           command: yarn lint
-      #- run: yarn flow
+      - run:
+          name: Flow Types
+          # https://discuss.circleci.com/t/circleci-terminal-is-a-tty-but-term-is-not-set/9965/8
+          command: TERM=dumb yarn flow
       - run:
           name: TS Types
           command: yarn test:types

decls/i18n.js

@@ -52,6 +52,7 @@ declare type DateTimeFormatResult = string;
 declare type NumberFormatResult = string;
 declare type MissingHandler = (locale: Locale, key: Path, vm?: any) => string | void;
 declare type PostTranslationHandler = (str: string, key?: string) => string;
+declare type GetChoiceIndex = (choice: number, choicesLength: number) => number
 declare type ComponentInstanceCreatedListener = (newI18n: I18n, rootI18n: I18n) => void;
 
 declare type FormattedNumberPartType = 'currency' | 'decimal' | 'fraction' | 'group' | 'infinity' | 'integer' | 'literal' | 'minusSign' | 'nan' | 'plusSign' | 'percentSign';
@@ -144,7 +145,7 @@ declare interface I18n {
   setNumberFormat (locale: Locale, format: NumberFormat): void,
   mergeNumberFormat (locale: Locale, format: NumberFormat): void,
   n (value: number, ...args: any): NumberFormatResult,
-  getChoiceIndex: (choice: number, choicesLength: number) => number,
+  getChoiceIndex: GetChoiceIndex,
   pluralizationRules: PluralizationRules,
   preserveDirectiveContent: boolean
 };

src/index.js

@@ -62,6 +62,7 @@ export default class VueI18n {
   pluralizationRules: {
     [lang: string]: (choice: number, choicesLength: number) => number
   }
+  getChoiceIndex: GetChoiceIndex
 
   constructor (options: I18nOptions = {}) {
     // Auto install if it is not done yet and `window` has `Vue`.
@@ -110,6 +111,41 @@ export default class VueI18n {
     this._warnHtmlInMessage = options.warnHtmlInMessage || 'off'
     this._postTranslation = options.postTranslation || null
 
+    /**
+     * @param choice {number} a choice index given by the input to $tc: `$tc('path.to.rule', choiceIndex)`
+     * @param choicesLength {number} an overall amount of available choices
+     * @returns a final choice index
+    */
+    this.getChoiceIndex = (choice: number, choicesLength: number): number => {
+      const thisPrototype = Object.getPrototypeOf(this)
+      if (thisPrototype && thisPrototype.getChoiceIndex) {
+        const prototypeGetChoiceIndex = (thisPrototype.getChoiceIndex: any)
+        return (prototypeGetChoiceIndex: GetChoiceIndex).call(this, choice, choicesLength)
+      }
+
+      // Default (old) getChoiceIndex implementation - english-compatible
+      const defaultImpl = (_choice: number, _choicesLength: number) => {
+        _choice = Math.abs(_choice)
+
+        if (_choicesLength === 2) {
+          return _choice
+            ? _choice > 1
+              ? 1
+              : 0
+            : 1
+        }
+
+        return _choice ? Math.min(_choice, 2) : 0
+      }
+
+      if (this.locale in this.pluralizationRules) {
+        return this.pluralizationRules[this.locale].apply(this, [choice, choicesLength])
+      } else {
+        return defaultImpl(choice, choicesLength)
+      }
+    }
+
+
     this._exist = (message: Object, key: Path): boolean => {
       if (!message || !key) { return false }
       if (!isNull(this._path.getPathValue(message, key))) { return true }
@@ -231,7 +267,6 @@ export default class VueI18n {
 
   onComponentInstanceCreated (newI18n: I18n) {
     if (this._componentInstanceCreatedListener) {
-      // $FlowFixMe
       this._componentInstanceCreatedListener(newI18n, this)
     }
   }
@@ -680,34 +715,6 @@ export default class VueI18n {
     return choices[choice].trim()
   }
 
-  /**
-   * @param choice {number} a choice index given by the input to $tc: `$tc('path.to.rule', choiceIndex)`
-   * @param choicesLength {number} an overall amount of available choices
-   * @returns a final choice index
-  */
-  getChoiceIndex (choice: number, choicesLength: number): number {
-    // Default (old) getChoiceIndex implementation - english-compatible
-    const defaultImpl = (_choice: number, _choicesLength: number) => {
-      _choice = Math.abs(_choice)
-
-      if (_choicesLength === 2) {
-        return _choice
-          ? _choice > 1
-            ? 1
-            : 0
-          : 1
-      }
-
-      return _choice ? Math.min(_choice, 2) : 0
-    }
-
-    if (this.locale in this.pluralizationRules) {
-      return this.pluralizationRules[this.locale].apply(this, [choice, choicesLength])
-    } else {
-      return defaultImpl(choice, choicesLength)
-    }
-  }
-
   tc (key: Path, choice?: number, ...values: any): TranslateResult {
     return this._tc(key, this.locale, this._getMessages(), null, choice, ...values)
   }

test/unit/issues.test.js

@@ -569,7 +569,7 @@ describe('issues', () => {
         locale: 'ru',
         messages: {
           ru: {
-            car: '0 машин | 1 машина | {n} машины | {n} машин'
+            car: '0 машин | {n} машина | {n} машины | {n} машин'
           }
         },
         pluralizationRules: {
@@ -578,12 +578,12 @@ describe('issues', () => {
       })
       vm = new Vue({ i18n })
 
-      assert(vm.$tc('car', 0), '0 машин')
-      assert(vm.$tc('car', 1), '1 машина')
-      assert(vm.$tc('car', 2), '2 машины')
-      assert(vm.$tc('car', 4), '4 машины')
-      assert(vm.$tc('car', 12), '12 машин')
-      assert(vm.$tc('car', 21), '21 машина')
+      assert.strictEqual(vm.$tc('car', 0), '0 машин')
+      assert.strictEqual(vm.$tc('car', 1), '1 машина')
+      assert.strictEqual(vm.$tc('car', 2), '2 машины')
+      assert.strictEqual(vm.$tc('car', 4), '4 машины')
+      assert.strictEqual(vm.$tc('car', 12), '12 машин')
+      assert.strictEqual(vm.$tc('car', 21), '21 машина')
     })
 
     it('ensures backward-compatibility with #451', () => {
@@ -617,21 +617,21 @@ describe('issues', () => {
 
 
       i18n = new VueI18n({
-        locale: 'en',
+        locale: 'ru',
         messages: {
           ru: {
-            car: '0 машин | 1 машина | {n} машины | {n} машин'
+            car: '0 машин | {n} машина | {n} машины | {n} машин'
           }
         }
       })
       vm = new Vue({ i18n })
 
-      assert(vm.$tc('car', 0), '0 машин')
-      assert(vm.$tc('car', 1), '1 машина')
-      assert(vm.$tc('car', 2), '2 машины')
-      assert(vm.$tc('car', 4), '4 машины')
-      assert(vm.$tc('car', 12), '12 машин')
-      assert(vm.$tc('car', 21), '21 машина')
+      assert.strictEqual(vm.$tc('car', 0), '0 машин')
+      assert.strictEqual(vm.$tc('car', 1), '1 машина')
+      assert.strictEqual(vm.$tc('car', 2), '2 машины')
+      assert.strictEqual(vm.$tc('car', 4), '4 машины')
+      assert.strictEqual(vm.$tc('car', 12), '12 машин')
+      assert.strictEqual(vm.$tc('car', 21), '21 машина')
 
       // Set the default implementation back
       VueI18n.prototype.getChoiceIndex = defaultImpl
@@ -662,14 +662,14 @@ describe('issues', () => {
         },
         formatter: {
           interpolate (message, values, path) {
-            assert(path, testPath)
+            assert.strictEqual(path, testPath)
 
             return null // pass the case to the default formatter
           }
         }
       })
 
-      assert(i18n.t(testPath), 'Hello!')
+      assert.strictEqual(i18n.t(testPath), 'Hello!')
     })
   })