feat: add warning when pytest.ini and pyproject.toml are present

The behaviour does not change however users will be notified that
pytest.ini is selected over pyproject.toml and any configuration
related to pytest it may contain.

Author: sgaist

AUTHORS

@@ -403,6 +403,7 @@ Sadra Barikbin
 Saiprasad Kale
 Samuel Colvin
 Samuel Dion-Girardeau
+Samuel Gaist
 Samuel Jirovec
 Samuel Searles-Bryant
 Samuel Therrien (Avasam)

changelog/13330.improvement.rst

@@ -0,0 +1,3 @@
+Having both ``pytest.ini`` and ``pyproject.toml`` will now print a warning to make it clearer to the user that the former takes precedence over the latter.
+
+-- by :user:`sgaist`

src/_pytest/terminal.py

@@ -879,7 +879,14 @@ def pytest_report_header(self, config: Config) -> list[str]:
         result = [f"rootdir: {config.rootpath}"]
 
         if config.inipath:
-            result.append("configfile: " + bestrelpath(config.rootpath, config.inipath))
+            warning = ""
+            if config.inipath.name in ["pytest.ini", ".pytest.ini"]:
+                pyproject = config.rootpath / "pyproject.toml"
+                if pyproject.exists():
+                    warning = " (WARNING: ignoring pytest config in pyproject.toml!)"
+            result.append(
+                "configfile: " + bestrelpath(config.rootpath, config.inipath) + warning
+            )
 
         if config.args_source == Config.ArgsSource.TESTPATHS:
             testpaths: list[str] = config.getini("testpaths")

testing/test_terminal.py

@@ -2893,6 +2893,47 @@ def test_format_trimmed() -> None:
     assert _format_trimmed(" ({}) ", msg, len(msg) + 3) == " (unconditional ...) "
 
 
+def test_warning_when_init_trumps_pyproject_toml(
+    pytester: Pytester, monkeypatch: MonkeyPatch
+) -> None:
+    """Regression test for #7814."""
+    tests = pytester.path.joinpath("tests")
+    tests.mkdir()
+    pytester.makepyprojecttoml(
+        f"""
+        [tool.pytest.ini_options]
+        testpaths = ['{tests}']
+    """
+    )
+    pytester.makefile(".ini", pytest="")
+    result = pytester.runpytest()
+    result.stdout.fnmatch_lines(
+        [
+            "configfile: pytest.ini (WARNING: ignoring pytest config in pyproject.toml!)",
+        ]
+    )
+
+
+def test_no_warning_on_terminal_with_a_single_config_file(
+    pytester: Pytester, monkeypatch: MonkeyPatch
+) -> None:
+    """Regression test for #7814."""
+    tests = pytester.path.joinpath("tests")
+    tests.mkdir()
+    pytester.makepyprojecttoml(
+        f"""
+        [tool.pytest.ini_options]
+        testpaths = ['{tests}']
+    """
+    )
+    result = pytester.runpytest()
+    result.stdout.fnmatch_lines(
+        [
+            "configfile: pyproject.toml",
+        ]
+    )
+
+
 class TestFineGrainedTestCase:
     DEFAULT_FILE_CONTENTS = """
             import pytest