chore(fill): delete output directory if no tests were ran

src/pytest_plugins/filler/filler.py

@@ -9,6 +9,7 @@
 import configparser
 import datetime
 import os
+import shutil
 import warnings
 from enum import Enum
 from pathlib import Path
@@ -431,9 +432,28 @@ def pytest_terminal_summary(
     Emphasize that fixtures have only been filled; they must now be executed to
     actually run the tests.
     """
-    yield
     if config.fixture_output.is_stdout or hasattr(config, "workerinput"):  # type: ignore[attr-defined]
+        yield
         return
+    # if no tests were collected, suppress the "Generated html report" message;
+    # the html report will be deleted in pytest_sessionfinish hook
+    session = terminalreporter._session
+    if getattr(session, "testscollected", 0) == 0:
+        orig_write_sep = terminalreporter.write_sep
+
+        def filtered_write_sep(sep, msg, **kwargs):
+            if isinstance(msg, str) and "Generated html report:" in msg:
+                return  # swallow it
+            return orig_write_sep(sep, msg, **kwargs)
+
+        terminalreporter.write_sep = filtered_write_sep  # type: ignore
+        try:
+            yield  # let all other terminal_summary hooks run
+        finally:
+            terminalreporter.write_sep = orig_write_sep  # type: ignore
+    else:
+        # if tests ran, no action needed, just yield to run the rest of the hooks
+        yield
     stats = terminalreporter.stats
     if "passed" in stats and stats["passed"]:
         # Custom message for Phase 1 (pre-allocation group generation)
@@ -1162,6 +1182,7 @@ def pytest_collection_modifyitems(
         items.pop(i)
 
 
+@pytest.hookimpl(hookwrapper=True, tryfirst=True)
 def pytest_sessionfinish(session: pytest.Session, exitstatus: int):
     """
     Perform session finish tasks.
@@ -1179,25 +1200,35 @@ def pytest_sessionfinish(session: pytest.Session, exitstatus: int):
         pre_alloc_groups_folder = fixture_output.pre_alloc_groups_folder_path
         pre_alloc_groups_folder.mkdir(parents=True, exist_ok=True)
         session.config.pre_alloc_groups.to_folder(pre_alloc_groups_folder)
-        return
 
     if xdist.is_xdist_worker(session):
+        yield
         return
 
     if fixture_output.is_stdout or is_help_or_collectonly_mode(session.config):
+        yield
         return
 
     # Remove any lock files that may have been created.
     for file in fixture_output.directory.rglob("*.lock"):
         file.unlink()
 
-    # Generate index file for all produced fixtures.
+    yield  # ensure that the following runs after pytest-html's pytest_sessionfinish hook
+
+    # Generate index file for all produced fixtures, respectively remove output dir.
     if session.config.getoption("generate_index") and not session.config.getoption(
         "generate_pre_alloc_groups"
     ):
-        generate_fixtures_index(
-            fixture_output.directory, quiet_mode=True, force_flag=False, disable_infer_format=False
-        )
+        amount_of_collected_tests = getattr(session, "testscollected", 0)
+        if amount_of_collected_tests > 0:
+            generate_fixtures_index(
+                fixture_output.directory,
+                quiet_mode=True,
+                force_flag=False,
+                disable_infer_format=False,
+            )
+        else:
+            shutil.rmtree(fixture_output.output_path)
 
     # Create tarball of the output directory if the output is a tarball.
     fixture_output.create_tarball()

src/pytest_plugins/filler/tests/test_filler.py

@@ -624,6 +624,103 @@ def test_fixture_output_based_on_command_line_args(
         assert properties["build"] == build_name
 
 
+test_module_no_matching_tests = textwrap.dedent(
+    """\
+    import pytest
+
+    from ethereum_test_tools import Account, Environment, TestAddress, Transaction
+
+    @pytest.mark.valid_from("Paris")
+    def test_will_not_match_filter(state_test):
+        state_test(env=Environment(),
+                    pre={TestAddress: Account(balance=1_000_000)}, post={}, tx=Transaction())
+    """
+)
+
+
+def test_no_tests_collected_deletes_output_directory(testdir, default_t8n):
+    """
+    Test that when no tests are collected/run, the output directory is deleted.
+    """
+    tests_dir = testdir.mkdir("tests")
+
+    test_module = tests_dir.join("test_no_match.py")
+    test_module.write(test_module_no_matching_tests)
+
+    testdir.copy_example(name="src/cli/pytest_commands/pytest_ini_files/pytest-fill.ini")
+    args = [
+        "-c",
+        "pytest-fill.ini",
+        "-v",
+        "--t8n-server-url",
+        default_t8n.server_url,
+        "-k",
+        "no_such_test_contains_this_filter",  # Filter that won't match any test
+    ]
+
+    result = testdir.runpytest(*args)
+    result.assert_outcomes(
+        passed=0,
+        failed=0,
+        skipped=0,
+        errors=0,
+    )
+
+    # Check that no tests were selected (all were deselected)
+    assert "0 selected" in result.stdout.str()
+
+    # The output directory should be deleted when no tests ran
+    output_dir = Path(default_output_directory()).absolute()
+    assert not output_dir.exists(), (
+        f"Output directory {output_dir} should have been deleted when no tests ran"
+    )
+
+
+def test_html_report_message_suppressed_when_no_tests_ran(testdir, default_t8n):
+    """
+    Test that the HTML report message is suppressed when no tests are collected/run.
+    """
+    tests_dir = testdir.mkdir("tests")
+
+    test_module = tests_dir.join("test_no_match.py")
+    test_module.write(test_module_no_matching_tests)
+
+    testdir.copy_example(name="src/cli/pytest_commands/pytest_ini_files/pytest-fill.ini")
+    args = [
+        "-c",
+        "pytest-fill.ini",
+        "-v",
+        "--t8n-server-url",
+        default_t8n.server_url,
+        "-k",
+        "no_such_test_contains_this_filter",  # Filter that won't match any test
+    ]
+
+    result = testdir.runpytest(*args)
+    result.assert_outcomes(
+        passed=0,
+        failed=0,
+        skipped=0,
+        errors=0,
+    )
+
+    # Check that no tests were selected (all were deselected)
+    assert "0 selected" in result.stdout.str()
+
+    # The HTML report message should NOT be present when no tests ran
+    # (even though HTML reporting is enabled, the message should be suppressed)
+    stdout_str = result.stdout.str()
+    assert "Generated html report:" not in stdout_str, (
+        "HTML report message should be suppressed when no tests ran"
+    )
+
+    # The output directory should still be deleted when no tests ran
+    output_dir = Path(default_output_directory()).absolute()
+    assert not output_dir.exists(), (
+        f"Output directory {output_dir} should have been deleted when no tests ran"
+    )
+
+
 test_module_environment_variables = textwrap.dedent(
     """\
     import pytest