selftests: drv-net: test dumping qstats per device

Add a test for dumping qstats device by device.

ksft framework grows a ksft_raises() helper, to be used
under with, which should be familiar to unittest users.

Link: https://lore.kernel.org/r/20240420023543.3300306-5-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/tools/testing/selftests/net/lib/py/ksft.py b/tools/testing/selftests/net/lib/py/ksft.py
index 25f2572fa540..e7f79f6185b0 100644
--- a/tools/testing/selftests/net/lib/py/ksft.py
+++ b/tools/testing/selftests/net/lib/py/ksft.py
@@ -53,6 +53,24 @@ def ksft_ge(a, b, comment=""):
         _fail("Check failed", a, "<", b, comment)
 
 
+class ksft_raises:
+    def __init__(self, expected_type):
+        self.exception = None
+        self.expected_type = expected_type
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        if exc_type is None:
+            _fail(f"Expected exception {str(self.expected_type.__name__)}, none raised")
+        elif self.expected_type != exc_type:
+            _fail(f"Expected exception {str(self.expected_type.__name__)}, raised {str(exc_type.__name__)}")
+        self.exception = exc_val
+        # Suppress the exception if its the expected one
+        return self.expected_type == exc_type
+
+
 def ksft_busy_wait(cond, sleep=0.005, deadline=1, comment=""):
     end = time.monotonic() + deadline
     while True: