Fix Node.js 4 support

test/at-rule.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const AtRule = require('../lib/at-rule');
 const parse  = require('../lib/parse');
 

test/browser.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 jest.doMock('fs', () => ({ }));
 jest.doMock('chalk', () => ({ }));
 jest.doMock('supports-color', () => ({ }));

test/comment.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const Comment = require('../lib/comment');
 const parse   = require('../lib/parse');
 

test/container.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const Declaration = require('../lib/declaration');
 const parse       = require('../lib/parse');
 const Rule        = require('../lib/rule');

test/css-syntax-error.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const CssSyntaxError = require('../lib/css-syntax-error');
 const postcss        = require('../lib/postcss');
 

test/declaration.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const Declaration = require('../lib/declaration');
 const parse       = require('../lib/parse');
 const Rule        = require('../lib/rule');

test/lazy-result.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const LazyResult = require('../lib/lazy-result');
 const Processor  = require('../lib/processor');
 

test/list.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const list = require('../lib/list');
 
 it('space() splits list by spaces', () => {

test/map.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const PreviousMap = require('../lib/previous-map');
 const postcss     = require('../lib/postcss');
 

test/node.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const CssSyntaxError = require('../lib/css-syntax-error');
 const Declaration    = require('../lib/declaration');
 const postcss        = require('../lib/postcss');

test/parse.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const parse = require('../lib/parse');
 const Root  = require('../lib/root');
 

test/postcss.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const Processor = require('../lib/processor');
 const postcss   = require('../lib/postcss');
 

test/previous-map.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const parse = require('../lib/parse');
 
 const mozilla = require('source-map');

test/processor.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const LazyResult = require('../lib/lazy-result');
 const Processor  = require('../lib/processor');
 const postcss    = require('../lib/postcss');

test/result.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const Warning = require('../lib/warning');
 const postcss = require('../lib/postcss');
 const Result  = require('../lib/result');

test/root.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const Result = require('../lib/result');
 const parse  = require('../lib/parse');
 

test/rule.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const parse = require('../lib/parse');
 const Rule  = require('../lib/rule');
 

test/stringifier.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const Stringifier = require('../lib/stringifier');
 const Declaration = require('../lib/declaration');
 const AtRule      = require('../lib/at-rule');

test/stringify.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const stringify = require('../lib/stringify');
 const parse     = require('../lib/parse');
 

test/tokenize.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const tokenizer = require('../lib/tokenize');
 const Input    = require('../lib/input');
 

test/vendor.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const vendor = require('../lib/vendor');
 
 const VALUE = '-1px -1px 1px rgba(0, 0, 0, 0.2) inset';

test/warning.test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const Declaration = require('../lib/declaration');
 const Warning     = require('../lib/warning');
 const parse       = require('../lib/parse');