add smoke test for prototype namespace on release versions

test/smoke_test.py

@@ -1,5 +1,6 @@
 """Run smoke tests"""
 
+import re
 import sys
 from pathlib import Path
 
@@ -79,11 +80,21 @@ def main() -> None:
     print(f"torchvision: {torchvision.__version__}")
     print(f"torch.cuda.is_available: {torch.cuda.is_available()}")
 
-    # Turn 1.11.0aHASH into 1.11 (major.minor only)
-    version = ".".join(torchvision.__version__.split(".")[:2])
-    if version >= "0.16":
-        print(f"{torch.ops.image._jpeg_version() = }")
-        assert torch.ops.image._is_compiled_against_turbo()
+    # The "a0" after the semantic version should only be present on the main branch or nightly builds,
+    # but not release branches.
+    if re.match(r"\d+\.\d+\.\d+(?!a0)\+", torchvision.__version__):
+        try:
+            from torchvision import prototype
+        except ModuleNotFoundError:
+            pass
+        else:
+            raise AssertionError(
+                "torchvision.prototype available on a release version. "
+                "Run rm -r torchvision/prototype test/test_prototype* .github/workflows/prototype*"
+            )
+
+    print(f"{torch.ops.image._jpeg_version() = }")
+    assert torch.ops.image._is_compiled_against_turbo()
 
     smoke_test_torchvision()
     smoke_test_torchvision_read_decode()