Bug 1401876 - (Part 2) Add browser-chrome test for reopening picker. r=mconley

MozReview-Commit-ID: BjR0rVxkdT

--HG--
extra : rebase_source : 92c1d3fc55dbe0eb8c1524a7510bc6431f296a25

toolkit/content/tests/browser/browser_datetime_datepicker.js

@@ -172,6 +172,28 @@ add_task(async function test_datepicker_clicked() {
   await helper.tearDown();
 });
 
+/**
+ * Make sure picker is in correct state when it is reopened.
+ */
+add_task(async function test_datepicker_reopen_state() {
+  const inputValue = "2016-12-15";
+  const nextMonth = "2017-01-01";
+
+  await helper.openPicker(`data:text/html, <input type="date" value="${inputValue}">`);
+  // Navigate to the next month but does not commit the change
+  Assert.equal(helper.getElement(MONTH_YEAR).textContent, DATE_FORMAT(new Date(inputValue)));
+  helper.click(helper.getElement(BTN_NEXT_MONTH));
+  Assert.equal(helper.getElement(MONTH_YEAR).textContent, DATE_FORMAT(new Date(nextMonth)));
+  EventUtils.synthesizeKey("VK_ESCAPE", {}, window);
+
+  // Ensures the picker opens to the month of the input value
+  await BrowserTestUtils.synthesizeMouseAtCenter("input", {}, gBrowser.selectedBrowser);
+  await helper.waitForPickerReady();
+  Assert.equal(helper.getElement(MONTH_YEAR).textContent, DATE_FORMAT(new Date(inputValue)));
+
+  await helper.tearDown();
+});
+
 /**
  * When min and max attributes are set, calendar should show some dates as
  * out-of-range.

toolkit/content/tests/browser/head.js

@@ -148,8 +148,12 @@ class DateTimeTestHelper {
       await BrowserTestUtils.waitForEvent(this.panel, "DateTimePickerBindingReady")
     }
     this.frame = this.panel.dateTimePopupFrame;
+    await this.waitForPickerReady();
+  }
+
+  async waitForPickerReady() {
     await BrowserTestUtils.waitForEvent(this.frame, "load", true);
-    // Wait for picker elements to be ready and open panel transition to end
+    // Wait for picker elements to be ready
     await BrowserTestUtils.waitForEvent(this.frame.contentDocument, "PickerReady");
   }