Fix --fail-under for pytest

pytest raises SystemExit when it running as runpy.run_module and code block with --fail-under never ran before.

Author: ownik

src/slipcover/__main__.py

@@ -272,6 +272,8 @@ def printit(coverage, outfile):
 
     atexit.register(sci_atexit)
 
+    return_code = 0
+
     if args.script:
         # python 'globals' for the script being executed
         script_globals: Dict[Any, Any] = dict()
@@ -303,14 +305,17 @@ def printit(coverage, outfile):
         import runpy
         sys.argv = [*args.module, *args.script_or_module_args]
         with sc.ImportManager(sci, file_matcher):
-            runpy.run_module(*args.module, run_name='__main__', alter_sys=True)
+            try:
+                runpy.run_module(*args.module, run_name='__main__', alter_sys=True)
+            except SystemExit as e:
+                return_code = e.code
 
     if args.fail_under:
         cov = sci.get_coverage()
         if cov['summary']['percent_covered'] < args.fail_under:
             return 2
-    
-    return 0
+
+    return return_code
 
 
 if __name__ == "__main__":

tests/test_coverage.py

@@ -704,6 +704,11 @@ def test_fail_under(json_flag):
     p = subprocess.run(f"{sys.executable} -m slipcover {json_flag} --branch --fail-under 84 tests/branch.py".split(), check=False)
     assert 2 == p.returncode
 
+    p = subprocess.run(f"{sys.executable} -m slipcover --branch --fail-under 93 -m pytest tests/pyt.py".split(), check=False)
+    assert 0 == p.returncode
+
+    p = subprocess.run(f"{sys.executable} -m slipcover --branch --fail-under 94 -m pytest tests/pyt.py".split(), check=False)
+    assert 2 == p.returncode
 
 def test_reports_on_other_sources(tmp_path):
     out_file = tmp_path / "out.json"
@@ -1286,7 +1291,6 @@ def test_xml_flag_with_pytest(tmp_path):
     assert lines[7].get('branch') is None
     assert lines[7].get('condition-coverage') is None
     assert lines[7].get('missing-branches') is None
-    
     assert lines[8].get('number') == '10'
     assert lines[8].get('hits') == '1'
     assert lines[8].get('branch') is None
@@ -1399,7 +1403,6 @@ def test_xml_flag_with_branches_and_pytest(tmp_path):
     assert lines[7].get('branch') is None
     assert lines[7].get('condition-coverage') is None
     assert lines[7].get('missing-branches') is None
-    
     assert lines[8].get('number') == '10'
     assert lines[8].get('hits') == '1'
     assert lines[8].get('branch') is None