coverage config: Add some excludes

This makes the results more useful

Signed-off-by: Jussi Kukkonen <jkukkonen@google.com>

pyproject.toml

@@ -149,3 +149,13 @@ module = [
   "securesystemslib.*",
 ]
 ignore_missing_imports = "True"
+
+[tool.coverage.report]
+exclude_also = [
+    # abstract class method definition
+    "raise NotImplementedError",
+    # defensive programming: these cannot happen
+    "raise AssertionError",
+    # imports for mypy only
+    "if TYPE_CHECKING",
+]

requirements/test.txt

@@ -4,5 +4,5 @@
 -r pinned.txt
 
 # coverage measurement
-coverage==7.6.8
+coverage[toml]==7.6.8
 freezegun==1.5.1

tox.ini

@@ -17,7 +17,7 @@ changedir = tests
 commands =
     python3 --version
     python3 -m coverage run aggregate_tests.py
-    python3 -m coverage report -m --fail-under 97
+    python3 -m coverage report --rcfile {toxinidir}/pyproject.toml -m --fail-under 97
 
 deps =
     -r{toxinidir}/requirements/test.txt
@@ -38,7 +38,7 @@ commands_pre =
 
 commands =
     python3 -m coverage run aggregate_tests.py
-    python3 -m coverage report -m
+    python3 -m coverage report  --rcfile {toxinidir}/pyproject.toml -m
 
 [testenv:lint]
 changedir = {toxinidir}