Optimize use assert*() method in tests

[peter-gribanov]

Optimize use assert*() method in tests.

Change assertEquals() to assertSame().

Change

$this->assertTrue(is_callable(...));

to

$this->assertIsCallable(...);

[coveralls]

Coverage decreased (-17.0%) to 83.019% when pulling 20df735 on peter-gribanov:optimize_use_assert into beb38a0 on gpslab:2.0.

[coveralls]

Coverage decreased (-17.0%) to 83.019% when pulling 20df735 on peter-gribanov:optimize_use_assert into beb38a0 on gpslab:2.0.

[coveralls]

Coverage decreased (-17.0%) to 83.019% when pulling 20df735 on peter-gribanov:optimize_use_assert into beb38a0 on gpslab:2.0.

[coveralls]

Coverage decreased (-17.0%) to 83.019% when pulling 20df735 on peter-gribanov:optimize_use_assert into beb38a0 on gpslab:2.0.

[coveralls]

Coverage decreased (-17.0%) to 83.019% when pulling 20df735 on peter-gribanov:optimize_use_assert into beb38a0 on gpslab:2.0.

[coveralls]

Coverage remained the same at 100.0% when pulling 20df735 on peter-gribanov:optimize_use_assert into beb38a0 on gpslab:2.0.