Add more tests.

.gitignore

@@ -1,6 +1,7 @@
 node_modules
 npm-debug.log
+.size-snapshot.json
 cjs
 esm
 umd
-.size-snapshot.json
+lib

src/lang.ts

@@ -13,16 +13,22 @@ const anyIntervalRegexp = /({\s*(\-?\d+(\.\d+)?[\s*,\s*\-?\d+(\.\d+)?]*)\s*})|([
 export default class Lang {
   locale: string = null
   fallback: string = null
-  messages: FlattenObject = null
+  messages: FlattenObject = {}
 
   constructor(options: Options) {
+    if (!options) {
+      throw new Error('options must be defined')
+    }
+
     this.locale = options.locale || inferLocale() || DEFAULT_LOCALE
     this.fallback = options.fallback
     this.setMessages(options.messages)
   }
 
   setMessages(messages: Messages) {
-    this.messages = flat(messages)
+    if (messages) {
+      this.messages = flat(messages)
+    }
   }
 
   getLocale(): string | null {

test/lang.choice.test.ts

@@ -4,10 +4,8 @@ const messages = require('./fixture/messages')
 describe('The lang.choice() method', () => {
   let lang
 
-  beforeEach(function() {
-    lang = new Lang({
-      messages: messages
-    })
+  beforeEach(() => {
+    lang = new Lang({ messages })
   })
 
   it('should return the passed key when not found', () => {
@@ -36,12 +34,13 @@ describe('The lang.choice() method', () => {
       }
     })
     lang.setLocale('ru')
+
     expect(lang.choice('plural.year', 1)).toBe('1 год')
     expect(lang.choice('plural.year', 2)).toBe('2 года')
     expect(lang.choice('plural.year', 5)).toBe('5 лет')
   })
 
-  it('should return the expected message using math intervals', function() {
+  it('should return the expected message using math intervals', () => {
     lang.setMessages({
       'en.test': {
         set: '{0} a|{1} :count b|[2,Inf] :count c',
@@ -50,6 +49,7 @@ describe('The lang.choice() method', () => {
         infinityStar: '[*,-1] :count Negative|[0,*] :count Positive'
       }
     })
+
     expect(lang.choice('test.set', 0)).toBe('a')
     expect(lang.choice('test.set', 1)).toBe('1 b')
     expect(lang.choice('test.set', 2)).toBe('2 c')
@@ -79,12 +79,12 @@ describe('The lang.choice() method', () => {
     ).toBe('The foo must be accepted.')
   })
 
-  it('should return the expected message with changed locale', function() {
+  it('should return the expected message with changed locale', () => {
     expect(lang.choice('messages.home', 1)).toBe('Home')
     expect(lang.choice('messages.home', 1, {}, 'es')).toBe('Inicio')
   })
 
-  it('should return the expected message using the fallback language', function() {
+  it('should return the expected message using the fallback language', () => {
     lang.setMessages({
       'en.messages': {
         box: ':count box|:count boxes'

test/lang.test.ts

@@ -0,0 +1,18 @@
+import Lang from '../src/lang'
+const messages = require('./fixture/messages')
+
+describe('The Lang class object', () => {
+  it('should not throw on non options', () => {
+    expect(() => {
+      const lang = new Lang(null)
+      lang.get('foo')
+    }).toThrow()
+  })
+
+  it('should not throw on non messages', () => {
+    expect(() => {
+      const lang = new Lang({ messages: null })
+      lang.get('foo')
+    }).not.toThrow()
+  })
+})