tests: remove unused imports and mocks

tests/test_projectbuilder.py

@@ -13,15 +13,10 @@
 import build
 
 if sys.version_info >= (3, 8):  # pragma: no cover
-    import email
     from importlib import metadata as importlib_metadata
-
-    email_message_from_string = email.message_from_string
 else:  # pragma: no cover
     import importlib_metadata
 
-    email_message_from_string = importlib_metadata._compat.email_message_from_string
-
 if sys.version_info >= (3,):  # pragma: no cover
     build_open_owner = 'builtins'
 else:  # pragma: no cover
@@ -93,11 +88,6 @@ def test_check_dependency(requirement_string, expected):
 
 
 def test_init(mocker, test_flit_path, legacy_path, test_no_permission, test_bad_syntax_path):
-    modules = {
-        'flit_core.buildapi': None,
-        'setuptools.build_meta:__legacy__': None,
-    }
-    mocker.patch('importlib.import_module', modules.get)
     mocker.patch('pep517.wrappers.Pep517HookCaller')
 
     # correct flit pyproject.toml
@@ -174,7 +164,6 @@ def test_build_missing_backend(packages_path, distribution, tmpdir):
 
 
 def test_check_dependencies(mocker, test_flit_path):
-    mocker.patch('importlib.import_module', autospec=True)
     mocker.patch('pep517.wrappers.Pep517HookCaller.get_requires_for_build_sdist')
     mocker.patch('pep517.wrappers.Pep517HookCaller.get_requires_for_build_wheel')
 
@@ -211,7 +200,6 @@ def test_working_directory(tmp_dir):
 
 
 def test_build(mocker, test_flit_path, tmp_dir):
-    mocker.patch('importlib.import_module', autospec=True)
     mocker.patch('pep517.wrappers.Pep517HookCaller', autospec=True)
     mocker.patch('build._working_directory', autospec=True)
 
@@ -238,7 +226,6 @@ def test_build(mocker, test_flit_path, tmp_dir):
 
 
 def test_default_backend(mocker, legacy_path):
-    mocker.patch('importlib.import_module', autospec=True)
     mocker.patch('pep517.wrappers.Pep517HookCaller', autospec=True)
 
     builder = build.ProjectBuilder(legacy_path)
@@ -247,7 +234,6 @@ def test_default_backend(mocker, legacy_path):
 
 
 def test_missing_backend(mocker, test_no_backend_path):
-    mocker.patch('importlib.import_module', autospec=True)
     mocker.patch('pep517.wrappers.Pep517HookCaller', autospec=True)
 
     builder = build.ProjectBuilder(test_no_backend_path)
@@ -256,23 +242,20 @@ def test_missing_backend(mocker, test_no_backend_path):
 
 
 def test_missing_requires(mocker, test_no_requires_path):
-    mocker.patch('importlib.import_module', autospec=True)
     mocker.patch('pep517.wrappers.Pep517HookCaller', autospec=True)
 
     with pytest.raises(build.BuildException):
         build.ProjectBuilder(test_no_requires_path)
 
 
 def test_build_system_typo(mocker, test_typo):
-    mocker.patch('importlib.import_module', autospec=True)
     mocker.patch('pep517.wrappers.Pep517HookCaller', autospec=True)
 
     with pytest.warns(build.TypoWarning):
         build.ProjectBuilder(test_typo)
 
 
 def test_missing_outdir(mocker, tmp_dir, test_flit_path):
-    mocker.patch('importlib.import_module', autospec=True)
     mocker.patch('pep517.wrappers.Pep517HookCaller', autospec=True)
 
     builder = build.ProjectBuilder(test_flit_path)
@@ -284,7 +267,6 @@ def test_missing_outdir(mocker, tmp_dir, test_flit_path):
 
 
 def test_relative_outdir(mocker, tmp_dir, test_flit_path):
-    mocker.patch('importlib.import_module', autospec=True)
     mocker.patch('pep517.wrappers.Pep517HookCaller', autospec=True)
 
     builder = build.ProjectBuilder(test_flit_path)
@@ -295,7 +277,6 @@ def test_relative_outdir(mocker, tmp_dir, test_flit_path):
 
 
 def test_not_dir_outdir(mocker, tmp_dir, test_flit_path):
-    mocker.patch('importlib.import_module', autospec=True)
     mocker.patch('pep517.wrappers.Pep517HookCaller', autospec=True)
 
     builder = build.ProjectBuilder(test_flit_path)