make the thing

Tests/ariaTests/ariaTests.swift

@@ -1,8 +1,30 @@
+import Foundation
 import Testing
+
 @testable import aria
 
-@Test func example() async throws {
-    // Write your test here and use APIs like `#expect(...)` to check expected conditions.
-    // Swift Testing Documentation
-    // https://developer.apple.com/documentation/testing
+@Test func addUriParamsEncodesPositionalArray() throws {
+	let params = Aria2.AddUriParams(
+		secret: "s3cret",
+		uris: ["https://example.com/file.zip"],
+		options: ["dir": "/tmp"]
+	)
+
+	let data = try JSONEncoder().encode(params)
+	let value = try JSONSerialization.jsonObject(with: data) as! [Any]
+
+	#expect(value.count == 3)
+	#expect(value[0] as? String == "token:s3cret")
+	#expect(value[1] as? [String] == ["https://example.com/file.zip"])
+	#expect(value[2] as? [String: String] == ["dir": "/tmp"])
+}
+
+@Test func addUriParamsOmitsSecretAndOptions() throws {
+	let params = Aria2.AddUriParams(secret: nil, uris: ["magnet:?xt=1"], options: [:])
+
+	let data = try JSONEncoder().encode(params)
+	let value = try JSONSerialization.jsonObject(with: data) as! [Any]
+
+	#expect(value.count == 1)
+	#expect(value[0] as? [String] == ["magnet:?xt=1"])
 }