feat(content): function signatures + test cases

backend/data/questions/merge-strings-alternately.yaml

@@ -9,6 +9,26 @@ categories:
 patterns:
   - two-pointers
 
+function_signature: "def merge_alternately(word1: str, word2: str) -> str:"
+
+test_cases:
+  visible:
+    - input: { word1: "abc", word2: "pqr" }
+      expected: "apbqcr"
+    - input: { word1: "ab", word2: "pqrs" }
+      expected: "apbqrs"
+    - input: { word1: "abcd", word2: "pq" }
+      expected: "apbqcd"
+  hidden:
+    - input: { word1: "a", word2: "b" }
+      expected: "ab"
+    - input: { word1: "a", word2: "xyz" }
+      expected: "axyz"
+    - input: { word1: "xyz", word2: "a" }
+      expected: "xayz"
+    - input: { word1: "hello", word2: "world" }
+      expected: "hweolrllod"
+
 description: |
   You are given two strings `word1` and `word2`. Merge the strings by adding letters in alternating order, starting with `word1`. If a string is longer than the other, append the additional letters onto the end of the merged string.