Tests in root directory are not displayed in explorer

```python
#  foo.py
def bar(x):
    return x + 10

############################################

#  test_foo.py 
import foo


def test_a():
    assert 1 == 1


def test_b():
    assert foo.bar(5) == 15
```

* Create above files in an empty workspace folder
* Configure to use pytest
* Test explorer is empty