add fetchFullMessage, fetchSection to IMAPClient for MIME attachment retrieval

Packages/MagnumOpusCore/Tests/SyncEngineTests/MockIMAPClient.swift

@@ -22,6 +22,10 @@ final class MockIMAPClient: IMAPClientProtocol, @unchecked Sendable {
 	var expungedMailboxes: [String] = []
 	var appendedMessages: [(mailbox: String, message: Data, flags: [String])] = []
 	var serverCapabilities: Set<String> = ["IMAP4rev1", "MOVE"]
+	var fullMessages: [Int: String] = [:]
+	var sections: [String: Data] = [:] // key: "uid-section"
+	var fetchFullMessageCalls: [Int] = []
+	var fetchSectionCalls: [(uid: Int, mailbox: String, section: String)] = []
 
 	func connect() async throws {
 		connectCalled = true
@@ -61,6 +65,18 @@ final class MockIMAPClient: IMAPClientProtocol, @unchecked Sendable {
 		bodies[uid] ?? (nil, nil)
 	}
 
+	// MARK: - v0.5 attachment/MIME operations
+
+	func fetchFullMessage(uid: Int) async throws -> String {
+		fetchFullMessageCalls.append(uid)
+		return fullMessages[uid] ?? ""
+	}
+
+	func fetchSection(uid: Int, mailbox: String, section: String) async throws -> Data {
+		fetchSectionCalls.append((uid: uid, mailbox: mailbox, section: section))
+		return sections["\(uid)-\(section)"] ?? Data()
+	}
+
 	// MARK: - v0.3 write operations
 
 	func storeFlags(uid: Int, mailbox: String, add: [String], remove: [String]) async throws {