This is similar to `mock()` but it makes a partial mock. Method name could also be changed to `mockPartial()`

So instead of
```PHP
$this->instance(Abstract::class, Mockery::mock(Abstract::class, function ($mock) {
    $mock->shouldReceive('call')->once();
})->makePartial());
```

You can write
```PHP
$this->partialMock(Abstract::class, function ($mock) {
    $mock->shouldReceive('call')->once();
});
```