ContainerRegistry: Reject capital letters in repository names

Author: euanh

Sources/ContainerRegistry/ImageReference.swift

@@ -45,8 +45,6 @@ func splitName(_ name: String) throws -> (String, String) {
     return (String(tagSplit[0]), String(tagSplit[1]))
 }
 
-/// Repository refers a repository (image namespace) on a container registry
-
 /// ImageReference points to an image stored on a container registry
 public struct ImageReference: Sendable, Equatable, CustomStringConvertible, CustomDebugStringConvertible {
     /// The registry which contains this image
@@ -111,6 +109,7 @@ public struct ImageReference: Sendable, Equatable, CustomStringConvertible, Cust
 }
 
 extension ImageReference {
+    /// Repository refers a repository (image namespace) on a container registry
     public struct Repository: Sendable, Equatable, CustomStringConvertible, CustomDebugStringConvertible {
         var value: String
 
@@ -121,6 +120,10 @@ extension ImageReference {
                 throw RepositoryParseError.emptyString
             }
 
+            if (rawValue.contains { $0.isUppercase }) {
+                throw RepositoryParseError.containsUppercaseLetters(rawValue)
+            }
+
             value = rawValue
         }
 
@@ -134,7 +137,8 @@ extension ImageReference {
         }
     }
 
-    public enum RepositoryParseError: Error {
+    public enum RepositoryParseError: Error, Equatable {
         case emptyString
+        case containsUppercaseLetters(String)
     }
 }

Tests/ContainerRegistryTests/ImageReferenceTests.swift

@@ -134,6 +134,18 @@ struct ReferenceTests {
         #expect(throws: ImageReference.RepositoryParseError.emptyString) {
             try ImageReference(fromString: "", defaultRegistry: "default")
         }
+
+        #expect(throws: ImageReference.RepositoryParseError.emptyString) {
+            try ImageReference(fromString: "example.com/")
+        }
+
+        #expect(throws: ImageReference.RepositoryParseError.containsUppercaseLetters("helloWorld")) {
+            try ImageReference(fromString: "helloWorld", defaultRegistry: "default")
+        }
+
+        #expect(throws: ImageReference.RepositoryParseError.containsUppercaseLetters("helloWorld")) {
+            try ImageReference(fromString: "localhost:5555/helloWorld")
+        }
     }
 
     @Test