add blueprint + test helper for integration tests (#50)

Borrowing from an approach used by ember-cli-flash, we add a helper to
duplicate the behavior of the initializer when we're running an
integration test (where initializers are not loaded). Add a blueprint
that auto-installs this helper and loads it in tests/test-helepr.js.

README.md

@@ -37,6 +37,16 @@ Installation
 ember install ember-test-selectors
 ```
 
+When you install the addon, it should automatically generate a helper located at
+`tests/helpers/test-selectors.js` as well as add an import to load that helper
+in `tests/test-helper.js`. This sets up the component `data-test-*` auto-binding
+for integration tests.
+
+You can do this manually as well:
+
+```
+$ ember generate ember-test-selectors
+```
 
 Usage
 ------------------------------------------------------------------------------

blueprints/.eslintrc.js

@@ -0,0 +1,11 @@
+module.exports = {
+  parserOptions: {
+    ecmaVersion: 6,
+    sourceType: 'module'
+  },
+  env: {
+    node: null,
+    browser: true,
+    embertest: true,
+  },
+};

blueprints/files/tests/helpers/test-selectors.js

@@ -0,0 +1,11 @@
+import Ember from 'ember';
+import bindDataTestAttributes from 'ember-test-selectors/utils/bind-data-test-attributes';
+
+const { Component } = Ember;
+
+Component.reopen({
+  init() {
+    this._super(...arguments);
+    bindDataTestAttributes(this);
+  }
+});

blueprints/index.js

@@ -0,0 +1,17 @@
+var EOL = require('os').EOL;
+
+module.exports = {
+  description: 'Generates ember-test-selectors test helper',
+
+  afterInstall: function() {
+    var TEST_HELPER_PATH = 'tests/test-helper.js';
+    var IMPORT_STATEMENT = EOL + "import './helpers/test-selectors';";
+    var INSERT_AFTER = "import resolver from './helpers/resolver';";
+
+    return this.insertIntoFile(TEST_HELPER_PATH, IMPORT_STATEMENT, {
+      after: INSERT_AFTER
+    });
+  },
+
+  normalizeEntityName: function() {}
+};