Add a spec checking for .jshintignore handling

Adds a spec that checks whether any .jshintignore file is being properly
handled.

spec/fixtures/ignore/.jshintignore

@@ -0,0 +1 @@
+**/ignored.js

spec/fixtures/ignore/.jshintrc

@@ -0,0 +1,3 @@
+{
+  "unused": true
+}

spec/fixtures/ignore/checked.js

@@ -0,0 +1 @@
+var foo = 42;

spec/fixtures/ignore/ignored.js

@@ -0,0 +1 @@
+var foo = 42;

spec/linter-jshint-spec.js

@@ -6,16 +6,13 @@ import * as path from 'path';
 import linter from '../lib/main';
 
 const bitwisePath = path.join(__dirname, 'fixtures', 'bitwise', 'bitwise.js');
-const emptyPath = path.join(__dirname, 'fixtures', 'empty.js');
-const goodPath = path.join(__dirname, 'fixtures', 'good.js');
 
 describe('The JSHint provider for Linter', () => {
   const lint = linter.provideLinter().lint;
 
   beforeEach(async () => {
     await atom.packages.activatePackage('linter-jshint');
     await atom.packages.activatePackage('language-javascript');
-    await atom.workspace.open(bitwisePath);
   });
 
   it('should be in the packages list', () =>
@@ -46,12 +43,14 @@ describe('The JSHint provider for Linter', () => {
   });
 
   it('finds nothing wrong with an empty file', async () => {
+    const emptyPath = path.join(__dirname, 'fixtures', 'empty.js');
     const editor = await atom.workspace.open(emptyPath);
     const messages = await lint(editor);
     expect(messages.length).toBe(0);
   });
 
   it('finds nothing wrong with a valid file', async () => {
+    const goodPath = path.join(__dirname, 'fixtures', 'good.js');
     const editor = await atom.workspace.open(goodPath);
     const messages = await lint(editor);
     expect(messages.length).toBe(0);
@@ -75,4 +74,27 @@ describe('The JSHint provider for Linter', () => {
       expect(messages[0].range).toEqual([[0, 10], [0, 11]]);
     });
   });
+
+  describe('handles .jshintignore files', () => {
+    const ignoreDir = path.join(__dirname, 'fixtures', 'ignore');
+    const checkedPath = path.join(ignoreDir, 'checked.js');
+    const ignoredPath = path.join(ignoreDir, 'ignored.js');
+
+    it('works when in the same directory', async () => {
+      const checkEditor = await atom.workspace.open(checkedPath);
+      const ignoreEditor = await atom.workspace.open(ignoredPath);
+      const checkMessages = await lint(checkEditor);
+      const ignoreMessages = await lint(ignoreEditor);
+      const expected = "W098 - 'foo' is defined but never used.";
+
+      expect(checkMessages.length).toBe(1);
+      expect(checkMessages[0].type).toBe('Warning');
+      expect(checkMessages[0].html).not.toBeDefined();
+      expect(checkMessages[0].text).toBe(expected);
+      expect(checkMessages[0].filePath).toBe(checkedPath);
+      expect(checkMessages[0].range).toEqual([[0, 4], [0, 7]]);
+
+      expect(ignoreMessages.length).toBe(0);
+    });
+  });
 });