Inital add of lg functions with column logic

lib/_lg-logic.js

@@ -0,0 +1,15 @@
+module.exports = {
+
+  columnLogic: function(columnFraction, gutter, rounder) {
+    let widthValue = '';
+    let gutterLogic = '';
+
+    if (gutter !== 0) {
+      gutterLogic = ` - (${gutter} - ${gutter} * ${columnFraction})`;
+    }
+
+    widthValue = `calc(${rounder}% * ${columnFraction}${gutterLogic})`;
+    return widthValue
+  }
+
+};

test/lg-logic.js

@@ -0,0 +1,22 @@
+'use strict'
+
+const expect = require('chai').expect;
+const lgLogic = require('../lib/_lg-logic.js');
+
+
+describe('columnLogic works as it should', () => {
+  it('gutter and rounder ✅', () => {
+    const foo = lgLogic.columnLogic('1/3', 30, 100);
+
+    const expectedResult = `calc(100% * 1/3 - (30 - 30 * 1/3))`;
+
+    expect(foo).to.equal(expectedResult);
+  });
+  it('no gutter ✅', () => {
+    const foo = lgLogic.columnLogic('1/3', 0, 99.9);
+
+    const expectedResult = `calc(99.9% * 1/3)`;
+
+    expect(foo).to.equal(expectedResult);
+  });
+});