Add tests for encoding and decoding Flag

feature/make-flag-codable

Author: roanutil

Tests/ArgumentEncodingTests/FlagTests.swift

@@ -27,4 +27,52 @@ final class FlagTests: XCTestCase {
         }
         XCTAssertEqual(args, ["--verbose"])
     }
+
+    private struct FlagContainer: Equatable, Codable {
+        @Flag var flag: Bool
+    }
+
+    private struct BoolContainer: Equatable, Codable {
+        var flag: Bool
+    }
+
+    func testFlagEncode() throws {
+        let encoder = JSONEncoder()
+
+        let flagFalse = Flag("key", enabled: false)
+        XCTAssertEqual(try encoder.encode(flagFalse), try encoder.encode(false))
+
+        let flagTrue = Flag("key", enabled: true)
+        XCTAssertEqual(try encoder.encode(flagTrue), try encoder.encode(true))
+
+        let containerFalse = FlagContainer(flag: false)
+        XCTAssertEqual(try encoder.encode(containerFalse), try encoder.encode(BoolContainer(flag: false)))
+
+        let containerTrue = FlagContainer(flag: true)
+        XCTAssertEqual(try encoder.encode(containerTrue), try encoder.encode(BoolContainer(flag: true)))
+    }
+
+    func testFlagDecode() throws {
+        let decoder = JSONDecoder()
+
+        let encodedTrue = try XCTUnwrap("true".data(using: .utf8))
+        let encodedFalse = try XCTUnwrap("false".data(using: .utf8))
+
+        let encodedContainerTrue = try XCTUnwrap("""
+        {
+            "flag": true
+        }
+        """.data(using: .utf8))
+        let encodedContainerFalse = try XCTUnwrap("""
+        {
+            "flag": false
+        }
+        """.data(using: .utf8))
+
+        XCTAssertEqual(try decoder.decode(Flag.self, from: encodedTrue), Flag(wrappedValue: true))
+        XCTAssertEqual(try decoder.decode(Flag.self, from: encodedFalse), Flag(wrappedValue: false))
+
+        XCTAssertEqual(try decoder.decode(FlagContainer.self, from: encodedContainerTrue), FlagContainer(flag: true))
+        XCTAssertEqual(try decoder.decode(FlagContainer.self, from: encodedContainerFalse), FlagContainer(flag: false))
+    }
 }