tests: add pending spec for repeated stylelintrc keys (#41)

* implement unit test to highlight poor json config can break stylelint

* adds pending test

Because I did some investigation into stylelint's JSON parsing library (cosmiconfig) and wanted to add the fix there, but there were some blockers that we will have to get around another time.

Having this feedback in the master branch will be helpful.

test/.badstylelintrc

@@ -0,0 +1,6 @@
+{
+  "rules": {
+    "color-hex-length": "short",
+    "color-hex-length": "short"
+  }
+}

test/index.js

@@ -45,6 +45,23 @@ describe('stylelint-webpack-plugin', function () {
       });
   });
 
+  it.skip('fails when .stylelintrc is not a proper format', function () {
+    var badConfigFilePath = getPath('./.badstylelintrc');
+    var config = {
+      entry: './index',
+      plugins: [
+        new StyleLintPlugin({
+          configFile: badConfigFilePath
+        })
+      ]
+    };
+
+    return pack(assign({}, baseConfig, config))
+      .then(function (stats) {
+        expect(stats.compilation.errors).to.have.length(0);
+      });
+  });
+
   it('fails on errors when asked to', function () {
     var config = {
       context: './test/fixtures/test3',