chore: update coverage a bit (#1073)

Updating the setup for code coverage a bit, largely based on
pypa/build's setup.

Signed-off-by: Henry Schreiner <[email protected]>

Author: henryiii

noxfile.py

@@ -72,6 +72,7 @@ def _run_tests(
     if "--cov" in posargs:
         _extras.append("cov")
         posargs.append("--cov-config=pyproject.toml")
+        env["COVERAGE_CORE"] = "sysmon"
 
     install_arg = f"-e.[{','.join(_extras)}]"
     session.install(install_arg, *install_args, silent=False)

pyproject.toml

@@ -214,8 +214,11 @@ messages_control.disable = [
 [tool.coverage]
 run.source = ["scikit_build_core"]
 run.omit = ["src/scikit_build_core/_vendor"]
-report.exclude_lines = [
-    'pragma: no cover',
+run.disable_warnings = [
+  "module-not-measured",  # Triggers in multithreaded context on build
+  "no-sysmon",
+]
+report.exclude_also = [
     '\.\.\.',
     'if typing.TYPE_CHECKING:',
     'if TYPE_CHECKING:',