Fix "# noqa: F401" placement for coverage by import tests

Author: LuKrO2011

src/pynguin/generator.py

@@ -1022,6 +1022,8 @@ def _export_chromosome(
         module_ast,
         target_file,
         format_with_black=config.configuration.test_case_output.format_with_black,
-        coverage_by_import_only=coverage_by_import_only,
+        module_name_with_coverage=config.configuration.module_name
+        if coverage_by_import_only
+        else None,
     )
     _LOGGER.info("Written %i test cases to %s", chromosome.size(), target_file)

src/pynguin/testcase/export.py

@@ -10,6 +10,7 @@
 import dataclasses
 import importlib.util
 import logging
+import re
 import sys
 from pathlib import Path
 
@@ -315,7 +316,7 @@ def save_module_to_file(
     target: Path,
     *,
     format_with_black: bool = True,
-    coverage_by_import_only: bool = False,
+    module_name_with_coverage: str | None = None,
 ) -> None:
     """Saves an AST module to a file.
 
@@ -324,7 +325,7 @@ def save_module_to_file(
         module: The AST module
         format_with_black: ast.unparse is not PEP-8 compliant, so we apply black
             on the result.
-        coverage_by_import_only: If True, adds a comment explaining that importing
+        module_name_with_coverage: If provided, adds a comment explaining that importing
             the module achieves coverage, and appends '# noqa: F401' to the import
             statement to prevent it from being removed by linters.
     """
@@ -343,8 +344,10 @@ def save_module_to_file(
             except black.parsing.InvalidInput as e:
                 _LOGGER.warning("Could not format the module '%s' with black: %s", target, e)
 
-        if coverage_by_import_only:
+        if module_name_with_coverage:
             file.write(_COVERAGE_BY_IMPORT_COMMENT)
-            output = output.rstrip("\n") + "  # noqa: F401\n"
+            # Add
+            pattern = re.compile(rf"^import {re.escape(module_name_with_coverage)}\b", re.MULTILINE)
+            output = pattern.sub(rf"import {module_name_with_coverage}  # noqa: F401", output)
 
         file.write(output)

tests/testcase/export/test_export.py

@@ -281,7 +281,7 @@ def test_case_1():
             module_ast,
             target_file,
             format_with_black=config.configuration.test_case_output.format_with_black,
-            coverage_by_import_only=coverage_by_import_only,
+            module_name_with_coverage=module_name if coverage_by_import_only else None,
         )
     assert target_file.exists()
     content = target_file.read_text(encoding="utf-8")
@@ -347,7 +347,7 @@ def _import_execute_export(
                 module_ast,
                 export_path,
                 format_with_black=config.configuration.test_case_output.format_with_black,
-                coverage_by_import_only=coverage_by_import_only,
+                module_name_with_coverage=module_name if coverage_by_import_only else None,
             )
 
         exported = export_path.read_text(encoding="utf-8")
@@ -532,8 +532,8 @@ def test_import_export_no_xfail(
 
 def test_coverage_by_import_only(tmp_path: Path) -> None:
     """When no test cases exist, SUT is imported with coverage comment and an empty test."""
-    sut_module_name = "tests.fixtures.accessibles.accessible"
-    visitor = export.PyTestChromosomeToAstVisitor(sut_module_name=sut_module_name)
+    module_name = "tests.fixtures.accessibles.accessible"
+    visitor = export.PyTestChromosomeToAstVisitor(sut_module_name=module_name)
 
     module_ast, coverage_by_import_only = visitor.to_module()
 
@@ -544,13 +544,12 @@ def test_coverage_by_import_only(tmp_path: Path) -> None:
         module_ast,
         target_file,
         format_with_black=False,
-        coverage_by_import_only=coverage_by_import_only,
+        module_name_with_coverage=module_name if coverage_by_import_only else None,
     )
 
     content = target_file.read_text(encoding="utf-8")
 
     assert "# Importing this module achieves coverage." in content
-    assert "# noqa: F401" in content
-    assert "import tests.fixtures.accessibles.accessible" in content
+    assert "import tests.fixtures.accessibles.accessible  # noqa: F401" in content
     assert "def test_empty():" in content
     assert "    pass" in content