From 87edc09deaf56dc058631e9491596c54b1ce020b Mon Sep 17 00:00:00 2001
From: symonk <jackofspaces@gmail.com>
Date: Mon, 13 Apr 2020 13:25:06 +0100
Subject: [PATCH] Gracefully handle eval() failure(s) for marker expressions

---
 AUTHORS                    |  1 +
 changelog/4583.bugfix.rst  |  1 +
 src/_pytest/mark/legacy.py |  9 ++++++--
 testing/test_mark.py       | 47 +++++++++++++++++++++++++++++++++++---
 4 files changed, 53 insertions(+), 5 deletions(-)
 create mode 100644 changelog/4583.bugfix.rst

diff --git a/AUTHORS b/AUTHORS
index 6efc41d97..bbb8e463d 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -246,6 +246,7 @@ Segev Finer
 Serhii Mozghovyi
 Seth Junot
 Simon Gomizelj
+Simon Kerr
 Skylar Downes
 Srinivas Reddy Thatiparthy
 Stefan Farmbauer
diff --git a/changelog/4583.bugfix.rst b/changelog/4583.bugfix.rst
new file mode 100644
index 000000000..64a680f14
--- /dev/null
+++ b/changelog/4583.bugfix.rst
@@ -0,0 +1 @@
+Prevent crashing and provide user friendly error(s) when marker expressions (-m) invoking of eval() raises a SyntaxError or TypeError
diff --git a/src/_pytest/mark/legacy.py b/src/_pytest/mark/legacy.py
index 80a520a0a..7581421da 100644
--- a/src/_pytest/mark/legacy.py
+++ b/src/_pytest/mark/legacy.py
@@ -84,8 +84,13 @@ def matchmark(colitem, markexpr):
     """Tries to match on any marker names, attached to the given colitem."""
     try:
         return eval(markexpr, {}, MarkMapping.from_item(colitem))
-    except SyntaxError as e:
-        raise SyntaxError(str(e) + "\nMarker expression must be valid Python!")
+    except (SyntaxError, TypeError):
+        raise UsageError(
+            "Marker expression provided to -m:{} was not valid python syntax."
+            " Please check the syntax provided and ensure it is correct".format(
+                markexpr
+            )
+        )
 
 
 def matchkeyword(colitem, keywordexpr):
diff --git a/testing/test_mark.py b/testing/test_mark.py
index 530f9f168..69f751012 100644
--- a/testing/test_mark.py
+++ b/testing/test_mark.py
@@ -608,10 +608,13 @@ class TestFunctional:
                 pass
         """
         )
-        result = testdir.runpytest("-m bogus/")
-        result.stdout.fnmatch_lines(
-            ["INTERNALERROR> Marker expression must be valid Python!"]
+        expected = (
+            "ERROR: Marker expression provided to -m: bogus/ was not valid python syntax. Please "
+            "check the syntax provided and ensure it is correct"
         )
+        result = testdir.runpytest("-m bogus/")
+        result.stderr.fnmatch_lines([expected])
+        assert result.ret == ExitCode.USAGE_ERROR
 
     def test_keywords_at_node_level(self, testdir):
         testdir.makepyfile(
@@ -1022,3 +1025,41 @@ def test_pytest_param_id_requires_string():
 @pytest.mark.parametrize("s", (None, "hello world"))
 def test_pytest_param_id_allows_none_or_string(s):
     assert pytest.param(id=s)
+
+
+def test_ux_eval_syntax_error(testdir):
+    foo = testdir.makepyfile(
+        """
+        import pytest
+
+        @pytest.mark.internal_err
+        def test_foo():
+            pass
+        """
+    )
+    expected = (
+        "ERROR: Marker expression provided to -m: NOT internal_err was not valid python syntax. Please "
+        "check the syntax provided and ensure it is correct"
+    )
+    result = testdir.runpytest(foo, "-m NOT internal_err")
+    result.stderr.fnmatch_lines([expected])
+    assert result.ret == ExitCode.USAGE_ERROR
+
+
+def test_ux_eval_type_error(testdir):
+    foo = testdir.makepyfile(
+        """
+        import pytest
+
+        @pytest.mark.internal_err
+        def test_foo():
+            pass
+        """
+    )
+    expected = (
+        "ERROR: Marker expression provided to -m: NOT (internal_err) was not valid python syntax. Please "
+        "check the syntax provided and ensure it is correct"
+    )
+    result = testdir.runpytest(foo, "-m NOT (internal_err)")
+    result.stderr.fnmatch_lines([expected])
+    assert result.ret == ExitCode.USAGE_ERROR