test: a general helper for iterating over our own source files

Author: nedbat

tests/helpers.py

@@ -26,6 +26,7 @@
 
 import flaky
 
+import coverage
 from coverage import env
 from coverage.debug import DebugControl
 from coverage.exceptions import CoverageWarning
@@ -373,3 +374,16 @@ def flaky_method(max_runs: int) -> Callable[[TestMethod], TestMethod]:
     def _decorator(fn: TestMethod) -> TestMethod:
         return cast(TestMethod, flaky.flaky(max_runs)(fn))
     return _decorator
+
+
+def all_our_source_files() -> Iterator[tuple[Path, str]]:
+    """Iterate over all of our own source files.
+
+    Produces a stream of (filename, file contents) tuples.
+    """
+    cov_dir = Path(coverage.__file__).parent.parent
+    # To run against all the files in the tox venvs:
+    #   for source_file in cov_dir.rglob("*.py"):
+    for sub in [".", "benchmark", "ci", "coverage", "lab", "tests"]:
+        for source_file in (cov_dir / sub).glob("*.py"):
+            yield (source_file, source_file.read_text(encoding="utf-8"))

tests/test_regions.py

@@ -11,10 +11,11 @@
 
 import pytest
 
-import coverage
 from coverage.plugin import CodeRegion
 from coverage.regions import code_regions
 
+from tests.helpers import all_our_source_files
+
 
 def test_code_regions() -> None:
     regions = code_regions(textwrap.dedent("""\
@@ -90,24 +91,21 @@ def test_real_code_regions() -> None:
     # Run code_regions on most of the coverage source code, checking that it
     # succeeds and there are no overlaps.
 
-    cov_dir = Path(coverage.__file__).parent.parent
     any_fails = False
-    # To run against all the files in the tox venvs:
-    #   for source_file in cov_dir.rglob("*.py"):
-    for sub in [".", "ci", "coverage", "lab", "tests"]:
-        for source_file in (cov_dir / sub).glob("*.py"):
-            regions = code_regions(source_file.read_text(encoding="utf-8"))
-            for kind in ["function", "class"]:
-                kind_regions = [reg for reg in regions if reg.kind == kind]
-                line_counts = collections.Counter(
-                    lno for reg in kind_regions for lno in reg.lines
+    for source_file, source in all_our_source_files():
+        regions = code_regions(source)
+        for kind in ["function", "class"]:
+            kind_regions = [reg for reg in regions if reg.kind == kind]
+            line_counts = collections.Counter(
+                lno for reg in kind_regions for lno in reg.lines
+            )
+            overlaps = [line for line, count in line_counts.items() if count > 1]
+            if overlaps:    # pragma: only failure
+                print(
+                    f"{kind.title()} overlaps in {source_file.relative_to(Path.cwd())}: "
+                    + f"{overlaps}"
                 )
-                overlaps = [line for line, count in line_counts.items() if count > 1]
-                if overlaps:    # pragma: only failure
-                    print(
-                        f"{kind.title()} overlaps in {source_file.relative_to(Path.cwd())}: "
-                        + f"{overlaps}"
-                    )
-                    any_fails = True
+                any_fails = True
+
     if any_fails:
         pytest.fail("Overlaps were found")  # pragma: only failure

tests/test_testing.py

@@ -22,6 +22,7 @@
 from tests.coveragetest import CoverageTest
 from tests.helpers import (
     CheckUniqueFilenames, FailingProxy,
+    all_our_source_files,
     arcz_to_arcs, assert_count_equal, assert_coverage_warnings,
     re_lines, re_lines_text, re_line,
 )
@@ -450,3 +451,13 @@ def subtract(self, a, b):               # type: ignore[no-untyped-def]
         proxy.add(3, 4)
     # then add starts working
     assert proxy.add(5, 6) == 11
+
+
+def test_all_our_source_files() -> None:
+    # Twas brillig and the slithy toves
+    i = 0
+    for i, (source_file, source) in enumerate(all_our_source_files(), start=1):
+        has_toves = (source_file.name == "test_testing.py")
+        assert (("# Twas brillig " + "and the slithy toves") in source) == has_toves
+        assert len(source) > 190    # tests/__init__.py is shortest at 196
+    assert 120 < i < 200            # currently 125 files