fixed missing coverage for one-line lambdas in 3.11

[xirafa]

For issue #59 :

One-line lambdas are missing coverage probes (3.11).

If a lambda is not executed, we don't get any indication.
This is due to interplay between dis.findlinestarts() which removes duplicated, and slipcover.findlinestarts() which ignores noop-like opcode of RESUME and RETURN_GENERATOR.

[jaltmayerpizzorno]

Thank you for your contribution! Any chance you'd be willing to add a test that replicates the issue?

[xirafa]

I added a simple test but apparently the current coverage report does report unexecuted lambdas as actually executed (probably due to covering the entire statement which defines the lambda).

Delving into this requires a bit more time than I have now - but probably someone might want to examine this further.

See the updated PR with the new test.

[jaltmayerpizzorno]

Python 3.11 tags the code that defines the lambda with the same line number as the lambda itself:

104          78 NOP
             80 PUSH_NULL
             82 LOAD_CONST               3 (<built-in function signal>)
             84 LOAD_CONST               6 (<capsule object NULL at 0x105fa8960>)
             86 PRECALL                  1
             90 CALL                     1
            100 POP_TOP
            102 LOAD_CONST               2 (<code object <lambda> at 0x106013930, file "/Users/juan/project/slipcover2/tests/test_coverage.py", line 104>)
            104 MAKE_FUNCTION            0
            
[...]

Disassembly of <code object <lambda> at 0x106013930, file "/Users/juan/project/slipcover2/tests/test_coverage.py", line 104>:
104           0 RESUME                   0
              2 LOAD_CONST               1 (24)
              4 RETURN_VALUE

With this, unfortunately, SlipCover can't differentiate between defining the lambda and executing it.