Do not initialize when parse is already initialized

[hermanliang]

If Parse is initialized in the application.
An IllegalStateException might be thrown when unit testing with Robolectric framework.

for example
MyApplication.java

public class MyApplication extends Application {
  @Override
  public void onCreate() {
    super.onCreate();
    Parse.initialize(this);
  }
}

SomeTest.java

@RunWith(RobolectricTestRunner.class)
@Config(constants = BuildConfig.class)
public class SomeTest {

  @Test
  public void test1() {
    ...
  }

  @Test
  public void test2() {
    ...
  }

}

Will get IllegalStateException: ParsePlugins is already initialized because of Robolectric setup application twice in the same testing session.

I think it would be better not to throw an exception when init parse more than once, just issue a warning log and do nothing.

It does not seems to be Robolectric's issue.
robolectric/robolectric#595
robolectric/robolectric#1981
robolectric/robolectric#2456

[codecov]

Codecov Report

Merging #640 into master will decrease coverage by 0.01%.
The diff coverage is 0%.

@@             Coverage Diff              @@
##             master     #640      +/-   ##
============================================
- Coverage     52.85%   52.84%   -0.02%     
  Complexity     1675     1675              
============================================
  Files           131      131              
  Lines         10142    10145       +3     
  Branches       1408     1408              
============================================
  Hits           5361     5361              
- Misses         4338     4340       +2     
- Partials        443      444       +1

Impacted Files	Coverage Δ	Complexity Δ
Parse/src/main/java/com/parse/Parse.java	49.76% <0%> (-0.7%)	23 <1> (ø)

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[Jawnnypoo]

Are we positive that the error was not being throw intentionally there to prevent some other side effects of having it init twice?

Side note: if you extend ResetPluginsParseTest it will fix this problem too.

[hermanliang]

@Jawnnypoo I think the behavior is not changed because this PR is still not allowing parse to init more than once.
BTW, ResetPluginsParseTest is in the SDK unit tests cannot be extended in application test class, but thanks anyway.

[natario1]

Since this is an application/developer issue, maybe it’s better to do this in Parse.initialize ? Something like if (isInitialized()) return.

ParsePlugins is private, I think the exception might come useful when writing internal tests for the SDK (ensures everything is tear down correctly, you know where you’re failing etc).

[hermanliang]

Thanks @natario1
You're right, we should keep the behavior in ParsePlugin.
Checking in Parse.initialized is a good idea. 😄