ContainerRegistry: Reject capital letters in repository names

Author: euanh

Sources/ContainerRegistry/ImageReference.swift

@@ -113,8 +113,9 @@ extension ImageReference {
     public struct Repository: Sendable, Equatable, CustomStringConvertible, CustomDebugStringConvertible {
         var value: String
 
-        public enum ValidationError: Error {
+        public enum ValidationError: Error, Equatable {
             case emptyString
+            case containsUppercaseLetters(String)
         }
 
         public init(_ rawValue: String) throws {
@@ -124,6 +125,10 @@ extension ImageReference {
                 throw ValidationError.emptyString
             }
 
+            if (rawValue.contains { $0.isUppercase }) {
+                throw ValidationError.containsUppercaseLetters(rawValue)
+            }
+
             value = rawValue
         }
 

Tests/ContainerRegistryTests/ImageReferenceTests.swift

@@ -170,6 +170,14 @@ struct ReferenceTests {
         #expect(throws: ImageReference.Repository.ValidationError.emptyString) {
             try ImageReference(fromString: "example.com/")
         }
+
+        #expect(throws: ImageReference.Repository.ValidationError.containsUppercaseLetters("helloWorld")) {
+            try ImageReference(fromString: "helloWorld", defaultRegistry: "default")
+        }
+
+        #expect(throws: ImageReference.Repository.ValidationError.containsUppercaseLetters("helloWorld")) {
+            try ImageReference(fromString: "localhost:5555/helloWorld")
+        }
     }
 
     @Test