Move xmldom parsing to internal interface (#19)

* Move xmldom parsing to internal interface

* fix lint errors

* add changelog update

CHANGELOG.md

@@ -22,6 +22,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 - Initial Release
+- Changed XML parsing to use an internal interface.
 
 <!-- Update the Unreleased comparison range with each release -->
 [Unreleased]: https://github.com/CondeNast/xml-to-react/compare/x.y.z...master

src/XMLToReact.js

@@ -1,18 +1,8 @@
-import { DOMParser } from 'xmldom';
+import { parse } from './parser';
 import { validateConverters, visitNode } from './helpers';
 
-const ERR_INVALID_XML = 'XMLToReact: Unable to parse invalid XML input. Please input valid XML.';
 const ERR_INVALID_CONVERTERS = 'XMLToReact: Invalid value for converter map argument. Please use an object with functions as values.';
 
-const throwError = (m) => { throw new Error(m); };
-
-const parser = new DOMParser({
-  errorHandler: throwError,
-  fatalError: throwError,
-  warning: throwError,
-});
-
-
 /**
  * Class representing an XML to React transformer.
  * @public
@@ -48,12 +38,8 @@ export default class XMLToReact {
       return null;
     }
 
-    let tree;
-
-    try {
-      tree = parser.parseFromString(xml, 'text/xml');
-    } catch (e) {
-      console.warn(ERR_INVALID_XML);
+    const tree = parse(xml);
+    if (!tree) {
       return null;
     }
 

src/parser.js

@@ -0,0 +1,33 @@
+import { DOMParser } from 'xmldom';
+
+export const ERR_INVALID_XML = 'XMLToReact: Unable to parse invalid XML input. Please input valid XML.';
+
+const throwError = (m) => { throw new Error(m); };
+
+const parser = new DOMParser({
+  errorHandler: throwError,
+  fatalError: throwError,
+  warning: throwError,
+});
+
+
+/**
+ * Parse an xml string
+ *
+ * @param {string} xml - xml to convert
+ * @returns {Object} - xml tree
+ * @public
+ */
+export function parse(xml) {
+  if (typeof xml !== 'string') {
+    return null;
+  }
+
+  try {
+    return parser.parseFromString(xml, 'text/xml');
+  } catch (e) {
+    console.warn(ERR_INVALID_XML);
+  }
+
+  return null;
+}

test/helpers.test.js

@@ -1,7 +1,7 @@
 import { expect } from 'chai';
-import { DOMParser } from 'xmldom';
 import { isValidElement } from 'react';
 import sinon from 'sinon';
+import { parse as parseXML } from '../src/parser';
 import {
   validateConverters,
   getAttributes,
@@ -10,19 +10,6 @@ import {
 } from '../src/helpers';
 
 describe('helpers', () => {
-  let parseXML;
-
-  before(() => {
-    // `parseXML` test helper to create XML nodes from strings
-    const throwError = (m) => { throw new Error(m); };
-    const parser = new DOMParser({
-      errorHandler: throwError,
-      fatalError: throwError,
-      warning: throwError,
-    });
-    parseXML = xml => parser.parseFromString(xml, 'text/xml');
-  });
-
   describe('validateConverters', () => {
     it('should export a function', () => {
       expect(validateConverters).to.be.a('function');

test/parser.test.js

@@ -0,0 +1,51 @@
+import { DOMParser } from 'xmldom';
+import { expect } from 'chai';
+import sinon from 'sinon';
+
+import { parse, ERR_INVALID_XML } from '../src/parser';
+
+describe('XML parser', () => {
+  let sandbox;
+
+  before(() => {
+    sandbox = sinon.sandbox.create();
+  });
+
+  afterEach(() => {
+    sandbox.restore();
+  });
+
+  describe('parse', () => {
+    it('should export a function', () => {
+      expect(parse).to.be.a('function');
+    });
+
+    it('should return `null` when no text is passed', () => {
+      expect(parse()).to.equal(null);
+      expect(parse('foo')).not.to.equal(null);
+    });
+
+    it('should parse XML from a string', () => {
+      const mockXMLTree = {};
+      sandbox.stub(DOMParser.prototype, 'parseFromString').returns(mockXMLTree);
+      expect(parse('foo')).to.equal(mockXMLTree);
+      sinon.assert.calledWith(DOMParser.prototype.parseFromString, 'foo', 'text/xml');
+    });
+
+    describe('When an invalid XML string is passed', () => {
+      beforeEach(() => {
+        sandbox.stub(console, 'warn');
+        sandbox.stub(DOMParser.prototype, 'parseFromString').throws(new Error('boom'));
+      });
+
+      it('should return `null`', () => {
+        expect(parse('foo')).to.equal(null);
+      });
+
+      it('should log a warning', () => {
+        parse('foo');
+        sinon.assert.calledWith(console.warn, ERR_INVALID_XML);
+      });
+    });
+  });
+});