WIP

tests/clipboredtests/ClipboardEncryptionServiceTests.swift

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+import CryptoKit
+import XCTest
+@testable import ClipBored
+
+final class ClipboardEncryptionServiceTests: XCTestCase {
+  func testProtectAndUnprotectRoundTrip() throws {
+    let service = makeService(byte: 7)
+    let value = "secret clipboard value \(UUID().uuidString)"
+
+    let protected = try XCTUnwrap(service.protect(value))
+
+    XCTAssertTrue(ClipboardEncryptionService.isProtected(protected))
+    XCTAssertFalse(protected.contains(value))
+    XCTAssertEqual(service.unprotect(protected), value)
+  }
+
+  func testUnprotectLeavesPlaintextValuesUntouched() {
+    let service = makeService(byte: 7)
+    let value = "plain clipboard value"
+
+    XCTAssertEqual(service.unprotect(value), value)
+  }
+
+  func testMarkerLookingPlaintextIsStillEncryptable() throws {
+    let service = makeService(byte: 7)
+    let value = ClipboardEncryptionService.marker + "not encrypted user text"
+
+    let protected = try XCTUnwrap(service.protect(value))
+
+    XCTAssertNotEqual(protected, value)
+    XCTAssertEqual(service.unprotect(protected), value)
+    XCTAssertEqual(service.unprotect(value), value)
+  }
+
+  func testWrongKeyCannotDecryptProtectedValue() throws {
+    let service = makeService(byte: 7)
+    let wrongService = makeService(byte: 9)
+    let protected = try XCTUnwrap(service.protect("keyed secret"))
+
+    XCTAssertNil(wrongService.unprotect(protected))
+  }
+
+  func testProtectDataAndUnprotectDataRoundTrip() throws {
+    let service = makeService(byte: 7)
+    let data = Data((0..<128).map { UInt8($0) })
+
+    let protected = service.protectData(data)
+
+    XCTAssertTrue(ClipboardEncryptionService.isProtected(protected))
+    XCTAssertNotEqual(protected, data)
+    XCTAssertEqual(service.unprotectData(protected), data)
+  }
+
+  func testWrongKeyCannotDecryptProtectedData() {
+    let service = makeService(byte: 7)
+    let wrongService = makeService(byte: 9)
+    let protected = service.protectData(Data("binary secret".utf8))
+
+    XCTAssertNil(wrongService.unprotectData(protected))
+  }
+
+  func testProtectFallsBackToPlaintextWhenKeyIsUnavailable() {
+    let service = ClipboardEncryptionService(keyProvider: { nil })
+
+    XCTAssertEqual(service.protect("available only in memory"), "available only in memory")
+    XCTAssertEqual(service.protectData(Data("available only in memory".utf8)), Data("available only in memory".utf8))
+  }
+
+  private func makeService(byte: UInt8) -> ClipboardEncryptionService {
+    let keyData = Data(repeating: byte, count: 32)
+    return ClipboardEncryptionService(keyProvider: { SymmetricKey(data: keyData) })
+  }
+}