add multipart/mixed formatting, base64 line-wrapped encoding to MessageFormatter

2026-03-14 13:32:23 +01:00
parent 968dd91f80
commit 0b9bbe1255
2 changed files with 149 additions and 0 deletions
@@ -173,4 +173,77 @@ struct MessageFormatterTests {
 		#expect(dateString.contains(","))
 		#expect(dateString.count > 20)
 	}
+
+	// MARK: - Multipart Formatting
+
+	@Test("format with attachments produces multipart/mixed")
+	func multipartWithAttachment() {
+		let message = OutgoingMessage(
+			from: EmailAddress(address: "alice@example.com"),
+			to: [EmailAddress(address: "bob@example.com")],
+			subject: "With attachment",
+			bodyText: "See attached.",
+			messageId: "test@example.com"
+		)
+		let attachments: [(filename: String, mimeType: String, data: Data)] = [
+			(filename: "test.pdf", mimeType: "application/pdf", data: Data("PDF content".utf8)),
+		]
+
+		let formatted = MessageFormatter.formatMultipart(message, attachments: attachments)
+
+		#expect(formatted.contains("Content-Type: multipart/mixed; boundary="))
+		#expect(formatted.contains("Content-Type: text/plain; charset=utf-8"))
+		#expect(formatted.contains("Content-Type: application/pdf; name=\"test.pdf\""))
+		#expect(formatted.contains("Content-Disposition: attachment; filename=\"test.pdf\""))
+		#expect(formatted.contains("Content-Transfer-Encoding: base64"))
+		#expect(formatted.contains("See attached."))
+	}
+
+	@Test("format without attachments produces single-part")
+	func singlePartNoAttachments() {
+		let message = OutgoingMessage(
+			from: EmailAddress(address: "alice@example.com"),
+			to: [EmailAddress(address: "bob@example.com")],
+			subject: "Plain",
+			bodyText: "Just text.",
+			messageId: "test@example.com"
+		)
+
+		let formatted = MessageFormatter.format(message)
+
+		#expect(formatted.contains("Content-Type: text/plain; charset=utf-8"))
+		#expect(!formatted.contains("multipart"))
+	}
+
+	@Test("base64 encoding wraps at 76 characters")
+	func base64LineWrapping() {
+		let data = Data(repeating: 0xFF, count: 100)
+		let encoded = MessageFormatter.base64Encode(data)
+		let lines = encoded.components(separatedBy: "\r\n")
+		for line in lines where !line.isEmpty {
+			#expect(line.count <= 76)
+		}
+	}
+
+	@Test("multiple attachments produce correct number of boundary sections")
+	func multipleAttachments() {
+		let message = OutgoingMessage(
+			from: EmailAddress(address: "alice@example.com"),
+			to: [EmailAddress(address: "bob@example.com")],
+			subject: "Multi",
+			bodyText: "Files.",
+			messageId: "test@example.com"
+		)
+		let attachments: [(filename: String, mimeType: String, data: Data)] = [
+			(filename: "a.pdf", mimeType: "application/pdf", data: Data("A".utf8)),
+			(filename: "b.jpg", mimeType: "image/jpeg", data: Data("B".utf8)),
+		]
+
+		let formatted = MessageFormatter.formatMultipart(message, attachments: attachments)
+
+		#expect(formatted.contains("a.pdf"))
+		#expect(formatted.contains("b.jpg"))
+		#expect(formatted.contains("application/pdf"))
+		#expect(formatted.contains("image/jpeg"))
+	}
 }