Support forwardslash characters in identifiers (#9249)

Closes #8377.

changelog/8377.bugfix.rst

@@ -0,0 +1,2 @@
+The test selection options ``pytest -k`` and ``pytest -m`` now support matching
+names containing forward slash (``/``) characters.

src/_pytest/mark/expression.py

@@ -6,7 +6,7 @@ expression: expr? EOF
 expr:       and_expr ('or' and_expr)*
 and_expr:   not_expr ('and' not_expr)*
 not_expr:   'not' not_expr | '(' expr ')' | ident
-ident:      (\w|:|\+|-|\.|\[|\]|\\)+
+ident:      (\w|:|\+|-|\.|\[|\]|\\|/)+
 
 The semantics are:
 
@@ -88,7 +88,7 @@ class Scanner:
                 yield Token(TokenType.RPAREN, ")", pos)
                 pos += 1
             else:
-                match = re.match(r"(:?\w|:|\+|-|\.|\[|\]|\\)+", input[pos:])
+                match = re.match(r"(:?\w|:|\+|-|\.|\[|\]|\\|/)+", input[pos:])
                 if match:
                     value = match.group(0)
                     if value == "or":

testing/test_mark.py

@@ -1111,7 +1111,7 @@ def test_pytest_param_id_allows_none_or_string(s) -> None:
     assert pytest.param(id=s)
 
 
-@pytest.mark.parametrize("expr", ("NOT internal_err", "NOT (internal_err)", "bogus/"))
+@pytest.mark.parametrize("expr", ("NOT internal_err", "NOT (internal_err)", "bogus="))
 def test_marker_expr_eval_failure_handling(pytester: Pytester, expr) -> None:
     foo = pytester.makepyfile(
         """

testing/test_mark_expression.py

@@ -144,6 +144,7 @@ def test_syntax_errors(expr: str, column: int, message: str) -> None:
         "a:::c",
         "a+-b",
         r"\nhe\\l\lo\n\t\rbye",
+        "a/b",
         "אבגד",
         "aaאבגדcc",
         "a[bcd]",
@@ -170,7 +171,6 @@ def test_valid_idents(ident: str) -> None:
 @pytest.mark.parametrize(
     "ident",
     (
-        "/",
         "^",
         "*",
         "=",