refactor: move all byte-size conversion logic to lib/shared/units.js (#1021)

This commit extracts the byte-related conversions from the `byte-size`
AngularJS module and the `FlashStateModel` to a re-usable generic
CommonJS module at `lib/shared/units.js`, than can also be used by the
CLI.

Signed-off-by: Juan Cruz Viotti <jviotti@openmailbox.org>

lib/gui/models/flash-state.js

@@ -25,6 +25,7 @@ const _ = require('lodash');
 const Store = require('./store');
 const MODULE_NAME = 'Etcher.Models.FlashState';
 const FlashState = angular.module(MODULE_NAME, []);
+const units = require('../../shared/units');
 
 FlashState.service('FlashStateModel', function() {
 
@@ -132,8 +133,8 @@ FlashState.service('FlashStateModel', function() {
         speed: _.attempt(() => {
           if (_.isNumber(state.speed) && !_.isNaN(state.speed)) {
 
-            // Transform bytes to megabytes preserving only two decimal places
-            return Math.floor(state.speed / 1e+6 * 100) / 100;
+            // Preserve only two decimal places
+            return Math.floor(units.bytesToMegabytes(state.speed) * 100) / 100;
 
           }
         })

lib/gui/utils/byte-size/filters/gigabyte.js

@@ -16,6 +16,8 @@
 
 'use strict';
 
+const units = require('../../../../shared/units');
+
 module.exports = () => {
 
   /**
@@ -29,8 +31,6 @@ module.exports = () => {
    * @example
    * {{ 7801405440 | gigabytes }}
    */
-  return (bytes) => {
-    return bytes / 1000000000;
-  };
+  return units.bytesToGigabytes;
 
 };

lib/shared/units.js

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2016 resin.io
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+'use strict';
+
+/**
+ * @summary Convert bytes to gigabytes
+ * @function
+ * @public
+ *
+ * @param {Number} bytes - bytes
+ * @returns {Number} gigabytes
+ *
+ * @example
+ * const result = units.bytesToGigabytes(7801405440);
+ */
+exports.bytesToGigabytes = (bytes) => {
+  return bytes / 1e+9;
+};
+
+/**
+ * @summary Convert bytes to megabytes
+ * @function
+ * @public
+ *
+ * @param {Number} bytes - bytes
+ * @returns {Number} megabytes
+ *
+ * @example
+ * const result = units.bytesToMegabytes(7801405440);
+ */
+exports.bytesToMegabytes = (bytes) => {
+  return bytes / 1e+6;
+};

tests/gui/utils/byte-size.spec.js

@@ -3,6 +3,7 @@
 const m = require('mochainon');
 const angular = require('angular');
 require('angular-mocks');
+const units = require('../../../lib/shared/units');
 
 describe('Browser: ByteSize', function() {
 
@@ -18,9 +19,8 @@ describe('Browser: ByteSize', function() {
       gigabyteFilter = _gigabyteFilter_;
     }));
 
-    it('should convert bytes to gigabytes', function() {
-      m.chai.expect(gigabyteFilter(7801405440)).to.equal(7.80140544);
-      m.chai.expect(gigabyteFilter(100000000)).to.equal(0.1);
+    it('should expose lib/shared/units.js bytesToGigabytes()', function() {
+      m.chai.expect(gigabyteFilter).to.equal(units.bytesToGigabytes);
     });
 
   });

tests/shared/units.spec.js

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2016 resin.io
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+'use strict';
+
+const m = require('mochainon');
+const units = require('../../lib/shared/units');
+
+describe('Shared: Units', function() {
+
+  describe('.bytesToGigabytes()', function() {
+
+    it('should convert bytes to gigabytes', function() {
+      m.chai.expect(units.bytesToGigabytes(7801405440)).to.equal(7.80140544);
+      m.chai.expect(units.bytesToGigabytes(100000000)).to.equal(0.1);
+    });
+
+    it('should convert bytes to megabytes', function() {
+      m.chai.expect(units.bytesToMegabytes(1.2e+7)).to.equal(12);
+      m.chai.expect(units.bytesToMegabytes(332000)).to.equal(0.332);
+    });
+
+  });
+
+});