fix: branch coverage

package.json

@@ -6,8 +6,8 @@
   "scripts": {
     "lint": "eslint .",
     "test": "mocha --recursive",
-    "coverage": "NODE_ENV=test istanbul cover --report html ./node_modules/mocha/bin/_mocha -- -R spec --recursive",
+    "coverage": "cross-env NODE_ENV=test istanbul cover --report html ./node_modules/mocha/bin/_mocha -- -R spec --recursive",
-    "lcov": "NODE_ENV=test istanbul cover --report lcovonly ./node_modules/mocha/bin/_mocha -- -R spec --recursive",
+    "lcov": "cross-env NODE_ENV=test istanbul cover --report lcovonly ./node_modules/mocha/bin/_mocha -- -R spec --recursive",
     "dist": "make dist",
     "preversion": "npm run lint && npm test",
     "version": "npm run dist && git add -A dist",
@@ -48,6 +48,7 @@
     "chai": "^4.1.2",
     "chai-as-promised": "^7.1.1",
     "coveralls": "^3.0.0",
+    "cross-env": "^5.1.3",
     "eslint": "^4.8.0",
     "eslint-config-standard": "^10.2.1",
     "eslint-plugin-import": "^2.7.0",

test/tags/include.js

@@ -24,6 +24,16 @@ describe('tags/include', function () {
       .eventually.equal('barfoobar')
   })
 
+  it('should throw when not specified', function () {
+    mock({
+      '/parent.html': '{%include%}'
+    })
+    return liquid.renderFile('/parent.html').catch(function (e) {
+      expect(e.name).to.equal('RenderError')
+      expect(e.message).to.match(/cannot include with empty filename/)
+    })
+  })
+
   it('should throw when not exist', function () {
     mock({
       '/parent.html': '{%include not-exist%}'

test/tags/layout.js

@@ -24,6 +24,15 @@ describe('tags/layout', function () {
     return expect(liquid.parseAndRender(src)).to
       .be.rejectedWith(/tag {%block%} not closed/)
   })
+  it('should throw when filename not specified', function () {
+    mock({
+      '/parent.html': '{%layout%}'
+    })
+    return liquid.renderFile('/parent.html').catch(function (e) {
+      expect(e.name).to.equal('RenderError')
+      expect(e.message).to.match(/cannot apply layout with empty filename/)
+    })
+  })
   describe('anonymous block', function () {
     it('should handle anonymous block', function () {
       mock({