Micro-blog: Add tests for different languages

Feedback from @SaschaMann
#1509 (comment)

> I think it would be nice to add some test cases that aren't emoji or
> English - perhaps cases with germanic umlauts, cyrillic and/or greek
> letters, historic scripts etc. - because that's one of the main uses
> and goals of unicode.

I've added German, Bulgarian, and Greek examples. All of them have
non-English characters.

None of these characters use multiple UTF-16 codepoints. As such, if you
use a UTF-8 programming language you may first have trouble with the
German example, but if you use a UTF-16 language you will probably first
have trouble at the Emoji example.

I chose not to add an example with historic scripts, because I'm not
aware of any that display nicely in my terminal or text-editor. Perhaps
in future some could be added.

I wanted another example that would be problematic in UTF-16, so I added
a poker hand example using playing cards.

exercises/micro-blog/canonical-data.json

@@ -9,8 +9,9 @@
     "This exercise is probably too easy in languages that use Unicode aware",
     "string slicing.",
     "",
-    "When adding additional tests to the problem specification, prefer tests",
-    "that pass and fail the same for UTF-8 and UTF-16.",
+    "When adding additional tests to the problem specification, consider that",
+    "in progress solutions might not fail due to UTF-8 and UTF-16",
+    "differences.",
     "",
     "Avoid adding tests that involve characters (graphemes) that are made up",
     "of multiple characters, or introduce them as a more advanced step.",
@@ -38,6 +39,38 @@
           },
           "expected": "Hello"
         },
+        {
+          "description": "German language short (broth)",
+          "property": "truncate",
+          "input": {
+            "phrase": "brühe"
+          },
+          "expected": "brühe"
+        },
+        {
+          "description": "Bulgarian language short (good)",
+          "property": "truncate",
+          "input": {
+            "phrase": "Добър"
+          },
+          "expected": "Добър"
+        },
+        {
+          "description": "Greek language short (health)",
+          "property": "truncate",
+          "input": {
+            "phrase": "υγειά"
+          },
+          "expected": "υγειά"
+        },
+        {
+          "description": "Maths short",
+          "property": "truncate",
+          "input": {
+            "phrase": "a=πr²"
+          },
+          "expected": "a=πr²"
+        },
         {
           "description": "English and emoji short",
           "property": "truncate",
@@ -61,6 +94,14 @@
             "phrase": "❄🌡🤧🤒🏥🕰😀"
           },
           "expected": "❄🌡🤧🤒🏥"
+        },
+        {
+          "description": "Royal Flush?",
+          "property": "truncate",
+          "input": {
+            "phrase": "🃎🂸🃅🃋🃍🃁🃊"
+          },
+          "expected": "🃎🂸🃅🃋🃍"
         }
       ]
     }