fix(android): Fix setting an active tab for TabGroup before opening.

[ypbnv]

JIRA: https://jira.appcelerator.org/browse/TIMOB-26843

Description:
Fixes setting an active tab for TabGroup before it is opened. Fixes backwards compatibility for
events - one unnecessary "focus" is currently triggered on TabGroup opening. Removes unused code. Clean up imports. Adds new unit tests. Updates docs.

Note: I have tested with both supported styles - default and bottom navigation. What I wonder is what is the best way to include the bottom navigation style in unit tests - add all the tests with it ( that would work, but for any new style possibly added later it may become too much work) or we use the style property randomly chosen for each test. With the latter we still may miss some edge cases.

I will try to figure out the failing of the "blur" unit tests since this PR changes event firing a little bit.

Test case:
app.js

var tabGroup = Ti.UI.createTabGroup();
 
var win1 = Titanium.UI.createWindow({
    title: 'Tab 1',
    backgroundColor: '#fff'
});
var tab1 = Titanium.UI.createTab({
title: 'Tab 1',
    window: win1
});
 
var label1 = Titanium.UI.createLabel({
    color: '#999',
    text: 'I am Window 1',
    textAlign: 'center',
    width: 'auto'
});
 
win1.add(label1);
var win2 = Titanium.UI.createWindow({
    title: 'Tab 2',
    backgroundColor: '#fff'
});
var tab2 = Titanium.UI.createTab({
    title: 'Tab 2',
    window: win2
});
 
var label2 = Titanium.UI.createLabel({
    color: '#999',
    text: 'I am Window 2',
    textAlign: 'center',
    width: 'auto'
});
 
win2.add(label2);
tabGroup.addTab(tab1);
tabGroup.addTab(tab2);
tabGroup.activeTab = 1;
Ti.API.info("### activeTab: " + tabGroup.activeTab);
tabGroup.open();

[build]

	Messages
📖	💾 Here's the generated SDK zipfile.
📖	✅ All tests are passing Nice one! All 344 tests are passing.

Generated by 🚫 dangerJS against e31cfa3

[jquick-axway]

This class' onTabSelected() method is missing a null check on the selectedTab member variable.

[ypbnv]

Are you referring to this onTabSelected() method?
https://github.com/appcelerator/titanium_mobile/blob/master/android/modules/ui/src/java/ti/modules/titanium/ui/TabGroupProxy.java#L529
If that is the case, it is intended for the selectedTab to be null in order to skip the sending of the focus/blur events when a tab is set as an active one before the opening of the TabGroup. But I may have not got what you mean.

[jquick-axway]

Oh you're right. Never mind.

[sgtcoolguy]

Note that the unit test around blur events is now failing, and is likely related to the changes in this area...

https://github.com/appcelerator/titanium-mobile-mocha-suite/blob/master/Resources/ti.ui.tabgroup.test.js#L232-L247

[ypbnv]

After some digging I found that the "blur" unit test started failing because this PR fixed firing a pair of focus/blur events that are not supposed to be fired. That problem was introduced at the same time when the unit test was added (Both by me) and this is the reason it didn't fail every single time in other PRs. With my latest update this should be cleared up.

[jquick-axway]

The unit test is passing now.

[jquick-axway]

We should check if getProxy() returns null in the selectTabItemInController() method and the onMenuItemClick() method, which can happen when the proxy has been released (ie: it's JavaScript object was garbage collected).

[ypbnv]

Updated.

[jquick-axway]

Looks good @ypbnv. I'm just asking for a few more null checks just in case. Thanks.

[keerthi1032]

FR Passed. Active tab works fine .some tests are failed in Jenkins.waiting for that to get resolved. also we need Backport PR FOR 8.0.
Operating System
Name = Mac OS X
Version = 10.13.6
Architecture = 64bit
Node.js
Node.js Version = 8.12.0
npm Version = 6.4.1
Titanium CLI
CLI Version = 5.1.1
Titanium SDK
SDK Version = 8.1.0.v20190301023310
Device =samsung s5 android 6
Emulator =google pixel 3 xL android 8

[jquick-axway]

CR: Pass

[ypbnv]

@jquick-axway Would you be able to take a look at my latest commit - I moved the nullifying of a Tab's parent - from when the views are released to when the Tab proxy itself is released. That is the reason the blur event was failing. Its source is the Tab and bubbles up to the TabGroup, but the focus change happens after the views of the TabGroup are released. And at the views release the parent was set to null, so in the end the event had nowhere to propagate to.