test(helpers): move helper that tests for errors to separate file

test/helpers/throws-error.js

@@ -0,0 +1,34 @@
+var values = [
+  undefined,
+  null,
+  0,
+  1,
+  true,
+  false,
+  {},
+  [],
+  function() {},
+  new Date()
+];
+
+/**
+ * Calls parser with invalid arguments.
+ *
+ * @param {Function} parser   - The parser.
+ * @param {Function} [assert] - The assertion module.
+ */
+function throwsError(parser, assert) {
+  if (typeof assert !== 'function') {
+    assert = require('assert');
+  }
+
+  values.forEach(function(value) {
+    it('throws error for argument: ' + value, function() {
+      assert.throws(function() {
+        parser(value);
+      }, TypeError);
+    });
+  });
+}
+
+module.exports = throwsError;

test/html-to-dom-server.js

@@ -1,6 +1,7 @@
 const { assert } = require('chai');
-const cases = require('./cases');
 const htmlparser = require('htmlparser2');
+const cases = require('./cases');
+const throwsError = require('./helpers/throws-error');
 const { CASE_SENSITIVE_TAG_NAMES } = require('../lib/constants');
 
 /**
@@ -18,22 +19,6 @@ function runTests(parser, cases) {
   });
 }
 
-/**
- * Throws tests (a helper that runs tests and verifies that error is thrown).
- *
- * @param {Function} parser - The parser.
- */
-function throwTests(parser) {
-  const values = [undefined, null, 1, true, {}, ['Array'], Function, Date];
-  values.forEach(value => {
-    it(`throws when argument is ${value}`, () => {
-      assert.throws(() => {
-        parser(value);
-      }, TypeError);
-    });
-  });
-}
-
 /**
  * Tests case-sensitive tags (SVG) to make sure their case is preserved.
  *
@@ -48,33 +33,28 @@ function testCaseSensitiveTags(parser) {
   });
 }
 
-/**
- * Tests for parser.
- */
 describe('server parser', () => {
+  // before
   const parser = require('../');
 
-  // check if invalid parameter type throws error
-  throwTests(parser);
-
-  // should be equivalent to `htmlparser2.parseDOM()`
+  // tests
+  throwsError(parser);
   runTests(parser, cases.html);
   runTests(parser, cases.svg);
 });
 
 describe('client parser in jsdom', () => {
+  // before
   const jsdomify = require('jsdomify').default;
   jsdomify.create();
   const parser = require('../lib/html-to-dom-client');
 
-  // check if invalid parameter type throws error
-  throwTests(parser);
-
-  // should return the same output as `htmlparser2.parseDOM()`
+  // tests
+  throwsError(parser);
   runTests(parser, cases.html);
   runTests(parser, cases.svg);
-
   testCaseSensitiveTags(parser);
 
+  // after
   jsdomify.destroy();
 });