Update tests for scrabble-score

Resolves #264.

Implements both of @dexterlemmer's proposals.

exercises/scrabble-score/tests/scrabble-score.rs

@@ -52,8 +52,8 @@ fn long_mixed_case_word() {
 #[test]
 #[ignore]
 fn non_english_scrabble_letters_do_not_score() {
-    assert_eq!(score("pinata"), 8);
-    assert_eq!(score("piñata"), 7);
+    assert_eq!(score("pinata"), 8, "'n' should score 1");
+    assert_eq!(score("piñata"), 7, "'ñ' should score 0");
 }
 
 #[test]
@@ -67,3 +67,10 @@ fn empty_words_are_worth_zero() {
 fn all_letters_work() {
     assert_eq!(score("abcdefghijklmnopqrstuvwxyz"), 87);
 }
+
+#[test]
+#[ignore]
+fn german_letters_do_not_score() {
+    assert_eq!(score("STRASSE"), 7, "\"SS\" should score 2.");
+    assert_eq!(score("STRAßE"), 5, "'ß' should score 0");
+}