test: add test to check that abi_str is in human readable format

ethers-contract/ethers-contract-abigen/src/contract.rs

@@ -255,3 +255,74 @@ fn parse_abi(abi_str: &str) -> Result<(Abi, bool, AbiParser)> {
     };
     Ok(res)
 }
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_abi_str_is_human_readable() {
+        let abi_str = r#"{
+            "abi": [
+              {
+                "type": "function",
+                "name": "allowance",
+                "inputs": [
+                  {
+                    "internalType": "address",
+                    "name": "owner",
+                    "type": "address"
+                  },
+                  {
+                    "internalType": "address",
+                    "name": "spender",
+                    "type": "address"
+                  }
+                ],
+                "outputs": [
+                  {
+                    "internalType": "uint256",
+                    "name": "",
+                    "type": "uint256"
+                  }
+                ],
+                "constant": false,
+                "stateMutability": "view"
+              },
+              {
+                "type": "function",
+                "name": "approve",
+                "inputs": [
+                  {
+                    "internalType": "address",
+                    "name": "spender",
+                    "type": "address"
+                  },
+                  {
+                    "internalType": "uint256",
+                    "name": "amount",
+                    "type": "uint256"
+                  }
+                ],
+                "outputs": [
+                  {
+                    "internalType": "bool",
+                    "name": "",
+                    "type": "bool"
+                  }
+                ],
+                "constant": false,
+                "stateMutability": "nonpayable"
+              }
+            ],
+            "bin": "0x",
+            "bin-runtime": "0x"
+          }"#;
+
+        let (abi, _, _) = parse_abi(&abi_str).unwrap();
+        let abi_str = serde_json::to_string(&abi).context("fail to serialize abi to json").unwrap();
+
+        assert!(&abi_str.starts_with('['));
+    }
+}