From 3823cc6d41956d0b8cfb55d6151673017a825c49 Mon Sep 17 00:00:00 2001
From: Ned Batchelder <ned@nedbatchelder.com>
Date: Tue, 27 Dec 2022 19:08:47 -0500
Subject: [PATCH] fix: [tools.coverage] is valid for settings in a toml file.
 #1516

---
 CHANGES.rst            |  9 +++++++++
 coverage/tomlconfig.py |  2 +-
 tests/test_config.py   | 13 +++++++++++++
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/CHANGES.rst b/CHANGES.rst
index ae3428cd6..54bbe7891 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -20,9 +20,18 @@ development at the same time, such as 4.5.x and 5.0.
 Unreleased
 ----------
 
+- Fix: if Python doesn't provide tomllib, then TOML configuration files can
+  only be read if coverage.py is installed with the ``[toml]`` extra.
+  Coverage.py will raise an error if toml support is not installed when it sees
+  your settings are in a .toml file. But it didn't understand that
+  ``[tools.coverage]`` was a valid section header, so the error wasn't
+  reported, and settings were silently ignored.  This is now fixed, closing
+  `issue 1516`_.
+
 - Fix: adjusted how decorators are traced on PyPy 7.3.10, fixing `issue 1515`_.
 
 .. _issue 1515: https://github.com/nedbat/coveragepy/issues/1515
+.. _issue 1516: https://github.com/nedbat/coveragepy/issues/1516
 
 
 .. _changes_7-0-1:
diff --git a/coverage/tomlconfig.py b/coverage/tomlconfig.py
index a7d390420..a25b3e35d 100644
--- a/coverage/tomlconfig.py
+++ b/coverage/tomlconfig.py
@@ -52,7 +52,7 @@ def read(self, filenames):
                 raise TomlDecodeError(str(err)) from err
             return [filename]
         else:
-            has_toml = re.search(r"^\[tool\.coverage\.", toml_text, flags=re.MULTILINE)
+            has_toml = re.search(r"^\[tool\.coverage(\.|])", toml_text, flags=re.MULTILINE)
             if self.our_file or has_toml:
                 # Looks like they meant to read TOML, but we can't read it.
                 msg = "Can't read {!r} without TOML support. Install with [toml] extra"
diff --git a/tests/test_config.py b/tests/test_config.py
index ccc4305fb..d88a1a4f7 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -739,6 +739,19 @@ def test_no_toml_installed_pyproject_toml(self):
             with pytest.raises(ConfigError, match=msg):
                 coverage.Coverage()
 
+    @pytest.mark.skipif(sys.version_info >= (3, 11), reason="Python 3.11 has toml in stdlib")
+    def test_no_toml_installed_pyproject_toml_shorter_syntax(self):
+        # Can't have coverage config in pyproject.toml without toml installed.
+        self.make_file("pyproject.toml", """\
+            # A toml file!
+            [tool.coverage]
+            run.parallel = true
+            """)
+        with without_module(coverage.tomlconfig, 'tomllib'):
+            msg = "Can't read 'pyproject.toml' without TOML support"
+            with pytest.raises(ConfigError, match=msg):
+                coverage.Coverage()
+
     def test_no_toml_installed_pyproject_no_coverage(self):
         # It's ok to have non-coverage pyproject.toml without toml installed.
         self.make_file("pyproject.toml", """\