Centralize mono/nuget skip predicate in conftest.py

Co-authored-by: oscarsj <1410188+oscarsj@users.noreply.github.com>

Author: Copilot

csharp/ql/integration-tests/posix/conftest.py

@@ -0,0 +1,20 @@
+import runs_on
+import pytest
+
+
+def _supports_mono_nuget():
+    """
+    Helper function to determine if the current platform supports Mono and nuget.
+    
+    Returns True if running on Linux or on macOS x86_64 (excluding macos-15 and macos-26).
+    macOS ARM runners (macos-15 and macos-26) are excluded due to issues with Mono and nuget.
+    """
+    return (
+        runs_on.linux
+        or (
+            runs_on.macos
+            and runs_on.x86_64
+            and not runs_on.macos_15
+            and not runs_on.macos_26
+        )
+    )

csharp/ql/integration-tests/posix/standalone_dependencies_no_framework/test.py

@@ -1,15 +1,9 @@
-import runs_on
 import pytest
 import os
+from conftest import _supports_mono_nuget
 
 
-# Skipping the test on the ARM runners, macos-15 and macos-26, as we're running
-# into trouble with Mono and nuget.
-@pytest.mark.only_if(
-    runs_on.linux
-    or (runs_on.macos and runs_on.x86_64
-        and not runs_on.macos_15 and not runs_on.macos_26)
-)
+@pytest.mark.only_if(_supports_mono_nuget())
 def test(codeql, csharp):
     os.environ["CODEQL_EXTRACTOR_CSHARP_BUILDLESS_DOTNET_FRAMEWORK_REFERENCES"] = (
         "/non-existent-path"

csharp/ql/integration-tests/posix/standalone_dependencies_nuget with_space/test.py

@@ -1,15 +1,9 @@
 import os
-import runs_on
 import pytest
+from conftest import _supports_mono_nuget
 
 
-# Skipping the test on the ARM runners, macos-15 and macos-26, as we're running
-# into trouble with Mono and nuget.
-@pytest.mark.only_if(
-    runs_on.linux
-    or (runs_on.macos and runs_on.x86_64
-        and not runs_on.macos_15 and not runs_on.macos_26)
-)
+@pytest.mark.only_if(_supports_mono_nuget())
 def test(codeql, csharp):
     # making sure we're not doing any fallback restore:
     os.environ["CODEQL_EXTRACTOR_CSHARP_BUILDLESS_NUGET_FEEDS_CHECK_FALLBACK_TIMEOUT"] = "1"

csharp/ql/integration-tests/posix/standalone_dependencies_nuget/test.py

@@ -1,19 +1,7 @@
-import runs_on
 import pytest
+from conftest import _supports_mono_nuget
 
 
-# Skipping the test on the ARM runners, macos-15 and macos-26, as we're running
-# into trouble with Mono and nuget.
-@pytest.mark.only_if(
-    runs_on.linux
-    or (
-        runs_on.macos
-        and runs_on.x86_64
-        and not (
-            runs_on.macos_15
-            or runs_on.macos_26
-        )
-    )
-)
+@pytest.mark.only_if(_supports_mono_nuget())
 def test(codeql, csharp):
     codeql.database.create(build_mode="none")

csharp/ql/integration-tests/posix/standalone_dependencies_nuget_no_sources/test.py

@@ -1,13 +1,7 @@
-import runs_on
 import pytest
+from conftest import _supports_mono_nuget
 
 
-# Skipping the test on the ARM runners, macos-15 and macos-26, as we're running
-# into trouble with Mono and nuget.
-@pytest.mark.only_if(
-    runs_on.linux
-    or (runs_on.macos and runs_on.x86_64
-        and not runs_on.macos_15 and not runs_on.macos_26)
-)
+@pytest.mark.only_if(_supports_mono_nuget())
 def test(codeql, csharp):
     codeql.database.create(source_root="proj", build_mode="none")