Use pytest data to extract the parametrised decoration

Rather than try and parse out the parametrized portion of the nodeid (delimited by square brackets but possibly containing square brackets), use native [pytest item attributes](https://docs.pytest.org/en/6.2.x/reference.html#function) to separate out the decoration.

Better solution for microsoft#17357, fixing microsoft#17676.

pythonFiles/testing_tools/adapter/pytest/_pytest_item.py

@@ -158,9 +158,21 @@ def parse_item(
     # Skip plugin generated tests
     if kind is None:
         return None, None
-    (nodeid, parents, fileid, testfunc, parameterized) = _parse_node_id(
-        item.nodeid, kind
-    )
+
+    if kind == "function" and item.originalname != item.name:
+        # split out parametrized decorations `node[params]`) before parsing
+        # and manually attach parametrized portion back in when done.
+        parameterized = item.name[len(item.originalname) :]
+        (parentid, parents, fileid, testfunc, _) = _parse_node_id(
+            item.nodeid[: -len(parameterized)], kind
+        )
+        nodeid = f"{parentid}{parameterized}"
+        parents = [(parentid, item.originalname, kind), *parents]
+    else:
+        (nodeid, parents, fileid, testfunc, parameterized) = _parse_node_id(
+            item.nodeid, kind
+        )
+
     # Note: testfunc does not necessarily match item.function.__name__.
     # This can result from importing a test function from another module.
 
@@ -434,32 +446,6 @@ def _parse_node_id(
     )
 
 
-def _find_left_bracket(nodeid):
-    """Return tuple of part before final bracket open, separator [, and the remainder.
-    Notes:
-        Testcase names in case of parametrized tests are wrapped in [<test-case-name>].
-    Examples:
-        dirname[sometext]/dirname/testfile.py::testset::testname[testcase]
-        => ('dirname[sometext]/dirname/testfile.py::testset::testname', '[', 'testcase]')
-        dirname/dirname/testfile.py::testset::testname[testcase]
-        => ('dirname/dirname/testfile.py::testset::testname', '[', 'testcase]')
-        dirname/dirname/testfile.py::testset::testname[testcase[x]]
-        => ('dirname/dirname/testfile.py::testset::testname', '[', 'testcase[x]]')
-    """
-    if not nodeid.endswith("]"):
-        return nodeid, "", ""
-    bracketcount = 0
-    for index, char in enumerate(nodeid[::-1]):
-        if char == "]":
-            bracketcount += 1
-        elif char == "[":
-            bracketcount -= 1
-        if bracketcount == 0:
-            n = len(nodeid) - 1 - index
-            return nodeid[:n], nodeid[n], nodeid[n + 1 :]
-    return nodeid, "", ""
-
-
 def _iter_nodes(
     testid,
     kind,
@@ -473,16 +459,6 @@ def _iter_nodes(
     if len(nodeid) > len(testid):
         testid = "." + _pathsep + testid
 
-    if kind == "function" and nodeid.endswith("]"):
-        funcid, sep, parameterized = _find_left_bracket(nodeid)
-        if not sep:
-            raise should_never_reach_here(
-                nodeid,
-                # ...
-            )
-        yield (nodeid, sep + parameterized, "subtest")
-        nodeid = funcid
-
     parentid, _, name = nodeid.rpartition("::")
     if not parentid:
         if kind is None: