Use supports-color module to test if system supports colors

This fixes #1574

lib/sinon/color.js

@@ -1,9 +1,9 @@
 "use strict";
 
-var canColor = typeof process !== "undefined";
+var supportsColor = require("supports-color");
 
 function colorize(str, color) {
-    if (!canColor) {
+    if (!supportsColor) {
         return str;
     }
 

package.json

@@ -40,6 +40,7 @@
     "lodash.get": "^4.4.2",
     "lolex": "^2.1.3",
     "nise": "^1.1.1",
+    "supports-color": "^4.4.0",
     "type-detect": "^4.0.0"
   },
   "devDependencies": {

test/util/core/color-test.js

@@ -0,0 +1,58 @@
+"use strict";
+
+var assert = require("referee").assert;
+var proxyquire = require("proxyquire");
+
+function getColorMethods() {
+    return [{
+        name: "red",
+        code: 31
+    }, {
+        name: "green",
+        code: 32
+    }];
+}
+
+describe("color", function () {
+    describe("when environment supports color", function () {
+        var color;
+
+        beforeEach(function () {
+            color = proxyquire("../../../lib/sinon/color", {
+                "supports-color": {}
+            });
+        });
+
+        getColorMethods().forEach(function (method) {
+            describe(method.name, function () {
+                it("should return a colored string", function () {
+                    var string = "lorem ipsum";
+                    var actual = color[method.name](string);
+
+                    assert.isTrue(actual.indexOf(method.code + "m" + string) !== -1);
+                });
+            });
+        });
+    });
+
+    describe("when environment does not support color", function () {
+        var color;
+
+        beforeEach(function () {
+            color = proxyquire("../../../lib/sinon/color", {
+                "supports-color": false
+            });
+        });
+
+        getColorMethods().forEach(function (method) {
+            describe(method.name, function () {
+                it("should return a colored string", function () {
+                    var string = "lorem ipsum";
+                    var actual = color[method.name](string);
+
+                    assert.equals(actual, string);
+                });
+            });
+        });
+    });
+});