add tests

Author: blva

tools/cli/internal/apiversion/version.go

@@ -150,7 +150,7 @@ func (v *APIVersion) IsPreview() bool {
 }
 
 func IsPreviewSabilityLevel(value string) bool {
-	return strings.Contains(value, PreviewStabilityLevel)
+	return strings.EqualFold(value, PreviewStabilityLevel) || strings.Contains(value, PreviewStabilityLevel) // we also need string match given private preview versions like "private-preview-<name>"
 }
 
 func IsStableSabilityLevel(value string) bool {

tools/cli/test/data/base_spec_with_preview.json

@@ -4038,7 +4038,10 @@
                   "$ref": "#/components/schemas/PaginatedAtlasGroupView"
                 },
                 "x-xgen-version": "preview",
-                "x-sunset": "2025-06-30"
+                "x-sunset": "2025-06-30",
+                "x-xgen-preview": {
+                    "name": "new-feature"                
+                }
               }
             }
           },