feat(content): function signatures + test cases

backend/data/questions/basic-calculator.yaml

@@ -10,6 +10,30 @@ categories:
 patterns:
   - monotonic-stack
 
+function_signature: "def calculate(s: str) -> int:"
+
+test_cases:
+  visible:
+    - input: { s: "1 + 1" }
+      expected: 2
+    - input: { s: " 2-1 + 2 " }
+      expected: 3
+    - input: { s: "(1+(4+5+2)-3)+(6+8)" }
+      expected: 23
+  hidden:
+    - input: { s: "1" }
+      expected: 1
+    - input: { s: "-1" }
+      expected: -1
+    - input: { s: "-(3+2)" }
+      expected: -5
+    - input: { s: "1-(5)" }
+      expected: -4
+    - input: { s: "2147483647" }
+      expected: 2147483647
+    - input: { s: "1-(-2)" }
+      expected: 3
+
 description: |
   Given a string `s` representing a valid expression, implement a basic calculator to evaluate it, and return *the result of the evaluation*.