# FlutterMain.setIsRunningInRobolectricTest on Android removed

> The test-only FlutterMain.setIsRunningInRobolectricTest API on the Android engine is consolidated into the FlutterInjector.




:::important
These breaking change docs are accurate, as of the release
under which they are published. Over time, the
workarounds described here might become inaccurate.
We don't, in general, keep these breaking change docs up
to date as of each release.

The [breaking change index file](/release/breaking-changes)
lists the docs created for each release.
:::


## Summary

If you write Java JUnit tests (such as Robolectric tests)
against the Flutter engine's Java embedding and used the
`FlutterMain.setIsRunningInRobolectricTest(true)` API,
replace it with the following:

```java
FlutterJNI mockFlutterJNI = mock(FlutterJNI.class);
FlutterInjector.setInstance(
        new FlutterInjector.Builder()
            .setFlutterLoader(new FlutterLoader(mockFlutterJNI))
            .build());
```

This should be very uncommon.

## Context

The `FlutterMain` class itself is being deprecated and replaced with the
`FlutterInjector` class. The `FlutterMain` class uses a number of
static variables and functions than make it difficult to test.
`FlutterMain.setIsRunningInRobolectricTest()` is one ad-hoc static
mechanism to allow tests to run on the host machine on JVM without
loading the `libflutter.so` native library
(which can't be done on the host machine).

Rather than one-off solutions, all dependency injections needed for tests
in Flutter's Android/Java engine embedding are now moved to the
[`FlutterInjector`] class.

[`FlutterInjector`]: https://cs.opensource.google/flutter/engine/+/master:shell/platform/android/io/flutter/FlutterInjector.java

Within the `FlutterInjector` class,
the `setFlutterLoader()` Builder
function allows for control of how the
[`FlutterLoader`][] class locates and loads
the `libflutter.so` library.

[`FlutterLoader`]: https://cs.opensource.google/flutter/engine/+/master:shell/platform/android/io/flutter/embedding/engine/loader/FlutterLoader.java

## Description of change

This [engine commit][] removed the
`FlutterMain.setIsRunningInRobolectricTest()` testing function;
and the following [commit][] added a
`FlutterInjector` class to assist testing.
[PR 20473][] further refactored `FlutterLoader`
and `FlutterJNI` to allow for additional mocking and testing.

[commit]: https://github.com/flutter/engine/commit/15f5696c4139a21e1fc54014ce17d01f6ad1737c#diff-f928557f2d60773a8435366400fa42ed
[engine commit]: https://github.com/flutter/engine/commit/15f5696c4139a21e1fc54014ce17d01f6ad1737c#diff-599e1d64442183ead768757cca6805c3L154
[PR 20473]: https://github.com/flutter/engine/pull/20473
to allow for additional mocking/testing.

## Migration guide

Code before migration:

```java
FlutterMain.setIsRunningInRobolectricTest(true);
```

Code after migration:

```java
FlutterJNI mockFlutterJNI = mock(FlutterJNI.class);
FlutterInjector.setInstance(
        new FlutterInjector.Builder()
            .setFlutterLoader(new FlutterLoader(mockFlutterJNI))
            .build());
```

## Timeline

Landed in version: 1.22.0-2.0.pre.133<br>
In stable release: 2.0.0