Add failing test for https://gitlab.com/gitlab-org/gitlab-ce/issues/37277

spec/javascripts/namespace_select_spec.js

+import NamespaceSelect from '~/namespace_select';
+
+describe('NamespaceSelect', () => {
+  beforeEach(() => {
+    spyOn($.fn, 'glDropdown');
+  });
+
+  it('initializes glDropdown', () => {
+    const dropdown = document.createElement('div');
+
+    // eslint-disable-next-line no-new
+    new NamespaceSelect({ dropdown });
+
+    expect($.fn.glDropdown).toHaveBeenCalled();
+  });
+
+  describe('as input', () => {
+    let glDropdownOptions;
+
+    beforeEach(() => {
+      const dropdown = document.createElement('div');
+      // eslint-disable-next-line no-new
+      new NamespaceSelect({ dropdown });
+      glDropdownOptions = $.fn.glDropdown.calls.argsFor(0)[0];
+    });
+
+    it('prevents click events', () => {
+      const dummyEvent = new Event('dummy');
+      spyOn(dummyEvent, 'preventDefault');
+
+      glDropdownOptions.clicked({ e: dummyEvent });
+
+      expect(dummyEvent.preventDefault).toHaveBeenCalled();
+    });
+  });
+
+  describe('as filter', () => {
+    let glDropdownOptions;
+
+    beforeEach(() => {
+      const dropdown = document.createElement('div');
+      dropdown.dataset.isFilter = 'true';
+      // eslint-disable-next-line no-new
+      new NamespaceSelect({ dropdown });
+      glDropdownOptions = $.fn.glDropdown.calls.argsFor(0)[0];
+    });
+
+    it('does not prevent click events', () => {
+      const dummyEvent = new Event('dummy');
+      spyOn(dummyEvent, 'preventDefault');
+
+      glDropdownOptions.clicked({ e: dummyEvent });
+
+      expect(dummyEvent.preventDefault).not.toHaveBeenCalled();
+    });
+
+    it('sets URL of dropdown items', () => {
+      const dummyNamespace = { id: 'eal' };
+
+      const itemUrl = glDropdownOptions.url(dummyNamespace);
+
+      expect(itemUrl).toContain(`namespace_id=${dummyNamespace.id}`);
+    });
+  });
+});