Add some more unit tests

src/generator.js

@@ -23,10 +23,15 @@ function pickWords (list, number) {
   return getWords(list, array)
 }
 
-function pickChar (options) {
+function getChar (choices, index) {
+  return choices[index % choices.length]
+}
+
+function pickChar (choices) {
   const array = new Uint32Array(1)
   window.crypto.getRandomValues(array)
-  return options[array[0] % options.length]
+  const index = array[0]
+  return getChar(choices, index)
 }
 
 function generate (options) {
@@ -61,5 +66,5 @@ function computeBits (options) {
 }
 
 module.exports = {
-  getWordList, getWords, capitalize, generate, lengthBits, computeBits
+  getWordList, getWords, capitalize, generate, getChar, lengthBits, computeBits
 }

tests/generator.js

@@ -0,0 +1,59 @@
+const { getWordList, getWords, getChar, lengthBits } = require('../src/generator')
+const words = require('../src/words')
+const assert = require('assert').strict
+const lists = ['small', 'medium', 'large']
+
+describe('getWordList', () => {
+  lists.forEach(name => {
+    it(name, () => {
+      assert.equal(getWordList(name), words[name])
+    })
+  })
+})
+
+describe('getWords', () => {
+  lists.forEach(name => {
+    it(`sanity: ${name}`, () => {
+      assert.deepEqual(
+        getWords(words[name], [0, 256, 1337, 2018]),
+        [words[name][0], words[name][256], words[name][1337], words[name][2018]]
+      )
+    })
+  })
+
+  lists.forEach(name => {
+    it(`all offsets: ${name}`, () => {
+      const len = words[name].length
+      ;[...Array(65536 / len)].forEach((_, i) => {
+        assert.deepEqual(
+          getWords(words[name], [i * len, i * len + 256, i * len + 1337, i * len + 2018]),
+          [words[name][0], words[name][256], words[name][1337], words[name][2018]]
+        )
+      })
+    })
+  })
+})
+
+describe('getChar', () => {
+  it('simple', () => {
+    const choices = ['0', '1', '2']
+    assert.equal(getChar(choices, 0), '0')
+    assert.equal(getChar(choices, 1), '1')
+    assert.equal(getChar(choices, 2), '2')
+    assert.equal(getChar(choices, 3), '0')
+    assert.equal(getChar(choices, 4), '1')
+    assert.equal(getChar(choices, 5), '2')
+  })
+})
+
+describe('lengthBits', () => {
+  it('simple', () => {
+    assert.equal(lengthBits(Array(1)), 0)
+    assert.equal(lengthBits(Array(2)), 1)
+    assert.equal(lengthBits(Array(4)), 2)
+    assert.equal(lengthBits(Array(1024)), 10)
+    assert.equal(lengthBits(Array(2048)), 11)
+    assert.equal(lengthBits(Array(4096)), 12)
+    assert.equal(lengthBits(Array(8192)), 13)
+  })
+})