Add tests for remainder of MASError

AppTests/MASErrorTestCase.swift

@@ -29,7 +29,8 @@ class MASErrorTestCase: XCTestCase {
 
     override func setUp() {
         super.setUp()
-        nserror = NSError(domain: errorDomain, code: 999) //, userInfo: ["NSLocalizedDescriptionKey": "foo"])
+        nserror = NSError(domain: errorDomain, code: 999)
+        localizedDescription = "foo"
     }
 
     override func tearDown() {
@@ -49,8 +50,52 @@ class MASErrorTestCase: XCTestCase {
     }
 
     func testSignInFailedError() {
-        localizedDescription = "foo"
         error = .signInFailed(error: nserror)
-        XCTAssertEqual("Sign in failed: foo", error.description)
+        XCTAssertEqual(error.description, "Sign in failed: foo")
+    }
+
+    func testAlreadySignedIn() {
+        error = .alreadySignedIn
+        XCTAssertEqual(error.description, "Already signed in")
+    }
+
+    func testPurchaseFailed() {
+        error = .purchaseFailed(error: nil)
+        XCTAssertEqual(error.description, "Download request failed")
+    }
+
+    func testPurchaseFailedError() {
+        error = .purchaseFailed(error: nserror)
+        XCTAssertEqual(error.description, "Download request failed: foo")
+    }
+
+    func testDownloadFailed() {
+        error = .downloadFailed(error: nil)
+        XCTAssertEqual(error.description, "Download failed")
+    }
+
+    func testDownloadFailedError() {
+        error = .downloadFailed(error: nserror)
+        XCTAssertEqual(error.description, "Download failed: foo")
+    }
+
+    func testNoDownloads() {
+        error = .noDownloads
+        XCTAssertEqual(error.description, "No downloads began")
+    }
+
+    func testCancelled() {
+        error = .cancelled
+        XCTAssertEqual(error.description, "Download cancelled")
+    }
+
+    func testSearchFailed() {
+        error = .searchFailed
+        XCTAssertEqual(error.description, "Search failed")
+    }
+
+    func testNoSearchResultsFound() {
+        error = .noSearchResultsFound
+        XCTAssertEqual(error.description, "No results found")
     }
 }