chore(test): refactored hash method into util (#470)

moved the hashing util out of the business
logic and added test coverage.

Fixes N/A

lib/karma-webpack.js

@@ -4,6 +4,8 @@ const fs = require('fs');
 const glob = require('glob');
 const minimatch = require('minimatch');
 
+const { hash } = require('./utils/hash');
+
 const { KarmaWebpackController } = require('./KarmaWebpackController');
 
 const controller = new KarmaWebpackController();
@@ -37,18 +39,6 @@ function registerExtraWebpackFiles(config, _controller) {
   });
 }
 
-/**
- * Simple hash function by bryc
- * https://gist.github.com/iperelivskiy/4110988#gistcomment-2697447
- */
-function hash(s) {
-  let h = 0xdeadbeef;
-  for (let i = 0; i < s.length; i++) {
-    h = Math.imul(h ^ s.charCodeAt(i), 2654435761); // eslint-disable-line no-bitwise
-  }
-  return (h ^ (h >>> 16)) >>> 0; // eslint-disable-line no-bitwise
-}
-
 function getPathKey(filePath, withExtension = false) {
   const pathParts = path.parse(filePath);
   const key = `${pathParts.name}.${hash(filePath)}`;

lib/utils/hash.js

@@ -0,0 +1,13 @@
+/**
+ * Simple hash function by bryc
+ * https://gist.github.com/iperelivskiy/4110988#gistcomment-2697447
+ */
+function hash(s) {
+  let h = 0xdeadbeef;
+  for (let i = 0; i < s.length; i++) {
+    h = Math.imul(h ^ s.charCodeAt(i), 2654435761); // eslint-disable-line no-bitwise
+  }
+  return (h ^ (h >>> 16)) >>> 0; // eslint-disable-line no-bitwise
+}
+
+module.exports = { hash };

test/KarmaWebpackController.test.js → test/unit/KarmaWebpackController.test.js

@@ -1,7 +1,7 @@
 const {
   KarmaWebpackController,
   defaultWebpackOptions,
-} = require('../lib/KarmaWebpackController');
+} = require('../../lib/KarmaWebpackController');
 
 describe('KarmaWebpackController', () => {
   it('applies the default webpackOptions', () => {

test/karma-webpack.test.js → test/unit/karma-webpack.test.js

@@ -1,7 +1,7 @@
 const fs = require('fs');
 const path = require('path');
 
-const { registerExtraWebpackFiles } = require('../lib/karma-webpack');
+const { registerExtraWebpackFiles } = require('../../lib/karma-webpack');
 
 jest.mock('fs');
 

test/unit/util/hash.test.js

@@ -0,0 +1,7 @@
+const { hash } = require('../../../lib/utils/hash');
+
+describe('HashService', () => {
+  it('should be able to reproducibly hash a string into a number', () => {
+    expect(hash('test')).toBe(3311036531);
+  });
+});