Fix snapshot filename collisions on case-insensitive filesystems

dotnet/test/Harness/E2ETestContext.cs

@@ -70,12 +70,9 @@ private static string GetCliPath(string repoRoot)
 
     public async Task ConfigureForTestAsync(string testFile, [CallerMemberName] string? testName = null)
     {
-        // Convert PascalCase method names to snake_case matching snapshot filenames
-        // e.g., Should_Create_A_Session_With_AvailableTools -> should_create_a_session_with_availableTools
-        var sanitizedName = Regex.Replace(testName!, @"_([A-Z])([A-Z]+)(_|$)", m =>
-            "_" + char.ToLowerInvariant(m.Groups[1].Value[0]) + m.Groups[2].Value.ToLowerInvariant() + m.Groups[3].Value);
-        sanitizedName = Regex.Replace(sanitizedName, @"(^|_)([A-Z])(?=[a-z]|_|$)", m =>
-            m.Groups[1].Value + char.ToLowerInvariant(m.Groups[2].Value[0]));
+        // Convert test method names to lowercase snake_case for snapshot filenames
+        // to avoid case collisions on case-insensitive filesystems (macOS/Windows)
+        var sanitizedName = Regex.Replace(testName!, @"[^a-zA-Z0-9]", "_").ToLowerInvariant();
         var snapshotPath = Path.Combine(_repoRoot, "test", "snapshots", testFile, $"{sanitizedName}.yaml");
         await _proxy.ConfigureAsync(snapshotPath, WorkDir);
     }

go/e2e/testharness/context.go

@@ -99,7 +99,7 @@ func (c *TestContext) ConfigureForTest(t *testing.T) {
 	parts := strings.SplitN(testName, "/", 2)
 
 	testFile := strings.ToLower(strings.TrimPrefix(parts[0], "Test"))
-	sanitizedName := regexp.MustCompile(`[^a-zA-Z0-9]`).ReplaceAllString(parts[1], "_")
+	sanitizedName := strings.ToLower(regexp.MustCompile(`[^a-zA-Z0-9]`).ReplaceAllString(parts[1], "_"))
 	snapshotPath := filepath.Join("..", "..", "test", "snapshots", testFile, sanitizedName+".yaml")
 
 	absSnapshotPath, err := filepath.Abs(snapshotPath)

nodejs/test/e2e/harness/sdkTestContext.ts

@@ -81,7 +81,7 @@ function getTrafficCapturePath(testContext: TestContext): string {
     }
 
     const testFileName = basename(testFilePath, suffix);
-    const taskNameAsFilename = testContext.task.name.replace(/[^a-z0-9]/gi, "_");
+    const taskNameAsFilename = testContext.task.name.replace(/[^a-z0-9]/gi, "_").toLowerCase();
     return join(SNAPSHOTS_DIR, testFileName, `${taskNameAsFilename}.yaml`);
 }
 

python/e2e/testharness/context.py

@@ -97,7 +97,7 @@ async def configure_for_test(self, test_file: str, test_name: str):
             test_file: The test file name (e.g., "session" from "test_session.py")
             test_name: The test name (e.g., "should_have_stateful_conversation")
         """
-        sanitized_name = re.sub(r"[^a-zA-Z0-9]", "_", test_name)
+        sanitized_name = re.sub(r"[^a-zA-Z0-9]", "_", test_name).lower()
         snapshot_path = SNAPSHOTS_DIR / test_file / f"{sanitized_name}.yaml"
         abs_snapshot_path = str(snapshot_path.resolve())