do this checking for lxml the right way

Author: wyattscarpenter

mypy/test/testcheck.py

@@ -5,6 +5,9 @@
 import os
 import re
 import sys
+from importlib.util import find_spec as import_exists
+
+import pytest
 
 from mypy import build
 from mypy.build import Graph
@@ -24,14 +27,6 @@
 )
 from mypy.test.update_data import update_testcase_output
 
-try:
-    pass  # import lxml #try just passing for now...
-except ImportError:
-    lxml_import_failure = True
-
-
-import pytest
-
 # List of files that contain test case descriptions.
 # Includes all check-* files with the .test extension in the test-data/unit directory
 typecheck_files = find_test_files(pattern="check-*.test")
@@ -55,7 +50,7 @@ class TypeCheckSuite(DataSuite):
     files = typecheck_files
 
     def run_case(self, testcase: DataDrivenTestCase) -> None:
-        if lxml_import_failure and os.path.basename(testcase.file) == "check-reports.test":
+        if import_exists("lmxl") and os.path.basename(testcase.file) == "check-reports.test":
             pytest.skip("Cannot import lxml. Is it installed?")
         incremental = (
             "incremental" in testcase.name.lower()

mypy/test/testcmdline.py

@@ -10,6 +10,9 @@
 import re
 import subprocess
 import sys
+from importlib.util import find_spec as import_exists
+
+import pytest
 
 from mypy.test.config import PREFIX, test_temp_dir
 from mypy.test.data import DataDrivenTestCase, DataSuite
@@ -19,13 +22,6 @@
     normalize_error_messages,
 )
 
-try:
-    pass  # import lxml #try just passing for now...
-except ImportError:
-    lxml_import_failure = True
-
-import pytest
-
 # Path to Python 3 interpreter
 python3_path = sys.executable
 
@@ -38,7 +34,7 @@ class PythonCmdlineSuite(DataSuite):
     native_sep = True
 
     def run_case(self, testcase: DataDrivenTestCase) -> None:
-        if lxml_import_failure and os.path.basename(testcase.file) == "reports.test":
+        if not import_exists("lxml") and os.path.basename(testcase.file) == "reports.test":
             pytest.skip("Cannot import lxml. Is it installed?")
         for step in [1] + sorted(testcase.output2):
             test_python_cmdline(testcase, step)

mypy/test/testreports.py

@@ -3,26 +3,24 @@
 from __future__ import annotations
 
 import textwrap
+from importlib.util import find_spec as import_exists
+
+import pytest
 
 from mypy.report import CoberturaPackage, get_line_rate
 from mypy.test.helpers import Suite, assert_equal
 
-try:
-    import lxml.etree as etree
-except ImportError:
-    lxml_import_failure = True
-
-import pytest
-
 
 class CoberturaReportSuite(Suite):
-    @pytest.mark.skipif(lxml_import_failure, reason="Cannot import lxml. Is it installed?")
+    @pytest.mark.skipif(not import_exists("lxml"), reason="Cannot import lxml. Is it installed?")
     def test_get_line_rate(self) -> None:
         assert_equal("1.0", get_line_rate(0, 0))
         assert_equal("0.3333", get_line_rate(1, 3))
 
-    @pytest.mark.skipif(lxml_import_failure, reason="Cannot import lxml. Is it installed?")
+    @pytest.mark.skipif(not import_exists("lxml"), reason="Cannot import lxml. Is it installed?")
     def test_as_xml(self) -> None:
+        import lxml.etree as etree
+
         cobertura_package = CoberturaPackage("foobar")
         cobertura_package.covered_lines = 21
         cobertura_package.total_lines = 42