Update reverse-string missing test cases

exercises/practice/reverse-string/.docs/instructions.append.md

@@ -0,0 +1,14 @@
+# Additional Instructions
+
+## Grapheme Clusters
+
+Unicode supports a lot of characters and languages.
+The displayed 'graphemes' are constructed from code points.
+Their combination and _order_ is the basis of the resulting grapheme.
+Imagine, a simple algorithm that might flip the 'dots' from one place to another during reversal: `Noël` becomes `leöN`.
+Now consider more [complex constructions][grapheme-construction] like the Bengali word `ঝিল্লি`, which consists of six code points.
+
+As graphemes make the string reversal process a lot more complicated, we made the respective test cases optional.
+You can try them out by setting the `TEST_GRAPHEMES` compiler flag or editing the test file accordingly.
+
+[grapheme-construction]: https://r12a.github.io/uniview/?charlist=%E0%A6%9D%E0%A6%BF%E0%A6%B2%E0%A7%8D%E0%A6%B2%E0%A6%BF

exercises/practice/reverse-string/.meta/tests.toml

@@ -1,6 +1,13 @@
-# This is an auto-generated file. Regular comments will be removed when this
-# file is regenerated. Regenerating will not touch any manually added keys,
-# so comments can be added in a "comment" key.
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
 
 [c3b7d806-dced-49ee-8543-933fd1719b1c]
 description = "an empty string"
@@ -19,3 +26,12 @@ description = "a palindrome"
 
 [b9e7dec1-c6df-40bd-9fa3-cd7ded010c4c]
 description = "an even-sized word"
+
+[1bed0f8a-13b0-4bd3-9d59-3d0593326fa2]
+description = "wide characters"
+
+[93d7e1b8-f60f-4f3c-9559-4056e10d2ead]
+description = "grapheme cluster with pre-combined form"
+
+[1028b2c1-6763-4459-8540-2da47ca512d9]
+description = "grapheme clusters"

exercises/practice/reverse-string/reverse_string_test.cpp

@@ -5,24 +5,52 @@
 #include "test/catch.hpp"
 #endif
 
-TEST_CASE("an_empty_string") {
+/*
+If property based testing tools are available, a good property to test is
+reversing a string twice: reverse(reverse(string)) == string
+*/
+
+TEST_CASE("an empty string", "[c3b7d806-dced-49ee-8543-933fd1719b1c]") {
     REQUIRE("" == reverse_string::reverse_string(""));
 }
 
 #if defined(EXERCISM_RUN_ALL_TESTS)
-TEST_CASE("a_word") {
+
+TEST_CASE("a word", "[01ebf55b-bebb-414e-9dec-06f7bb0bee3c]") {
     REQUIRE("tobor" == reverse_string::reverse_string("robot"));
 }
 
-TEST_CASE("a_capitalized_word") {
+TEST_CASE("a capitalized word", "[0f7c07e4-efd1-4aaa-a07a-90b49ce0b746]") {
     REQUIRE("nemaR" == reverse_string::reverse_string("Ramen"));
 }
 
-TEST_CASE("a_sentence_with_punctuation") {
+TEST_CASE("a sentence with punctuation",
+          "[71854b9c-f200-4469-9f5c-1e8e5eff5614]") {
     REQUIRE("!yrgnuh m'I" == reverse_string::reverse_string("I'm hungry!"));
 }
 
-TEST_CASE("a_palindrome") {
+TEST_CASE("a palindrome", "[1f8ed2f3-56f3-459b-8f3e-6d8d654a1f6c]") {
     REQUIRE("racecar" == reverse_string::reverse_string("racecar"));
 }
+
+TEST_CASE("an even-sized word", "[b9e7dec1-c6df-40bd-9fa3-cd7ded010c4c]") {
+    REQUIRE("reward" == reverse_string::reverse_string("drawer"));
+}
+
+#if defined(TEST_GRAPHEMES)
+TEST_CASE("wide characters", "[1bed0f8a-13b0-4bd3-9d59-3d0593326fa2]") {
+    REQUIRE("猫子" == reverse_string::reverse_string("子猫"));
+}
+
+TEST_CASE("grapheme cluster with pre-combined form",
+          "[93d7e1b8-f60f-4f3c-9559-4056e10d2ead]") {
+    REQUIRE("dnatsnehctsrüW" ==
+            reverse_string::reverse_string("Würstchenstand"));
+}
+
+TEST_CASE("grapheme clusters", "[1028b2c1-6763-4459-8540-2da47ca512d9]") {
+    REQUIRE("มรกแรปโนยขีเผู้" == reverse_string::reverse_string("ผู้เขียนโปรแกรม"));
+}
+#endif
+
 #endif