FEATURE: add an option to create undismissable modals

test/javascripts/acceptance/modal-test.js.es6

@@ -1,4 +1,6 @@
 import { acceptance } from "helpers/qunit-helpers";
+import showModal from 'discourse/lib/show-modal';
+
 acceptance("Modal");
 
 QUnit.test("modal", assert => {
@@ -27,4 +29,19 @@ QUnit.test("modal", assert => {
   andThen(() => {
     assert.ok(find('.d-modal:visible').length === 0, 'ESC should close the modal');
   });
+  andThen(() => {
+    Ember.TEMPLATES['modal/not-dismissable'] = Ember.HTMLBars.compile('{{#d-modal-body title="" class="" dismissable=false}}test{{/d-modal-body}}');
+    showModal('not-dismissable', {});
+  });
+  andThen(() => {
+    assert.ok(find('.d-modal:visible').length === 1, 'modal should appear');
+  });
+  click('.modal-outer-container');
+  andThen(() => {
+    assert.ok(find('.d-modal:visible').length === 1, 'modal should not disappear when you click outside');
+  });
+  keyEvent('#main-outlet', 'keydown', 27);
+  andThen(() => {
+    assert.ok(find('.d-modal:visible').length === 1, 'ESC should not close the modal');
+  });
 });