Add Json test

Author: grandizzy

crates/forge/tests/cli/cmd.rs

@@ -2897,4 +2897,54 @@ Suite result: ok. 1 passed; 0 failed; 0 skipped; [ELAPSED]
 ...
 
 "#]]);
+
+    cmd.forge_fuse()
+        .args(["test", "--mt", "test_fallback_gas_report", "--gas-report", "--json"])
+        .assert_success()
+        .stdout_eq(
+            str![[r#"
+[
+  {
+    "contract": "test/DelegateProxyTest.sol:DelegateProxy",
+    "deployment": {
+      "gas": 108698,
+      "size": 315
+    },
+    "functions": {
+      "deposit()": {
+        "calls": 1,
+        "min": 21160,
+        "mean": 21160,
+        "median": 21160,
+        "max": 21160
+      },
+      "fallback()": {
+        "calls": 1,
+        "min": 29396,
+        "mean": 29396,
+        "median": 29396,
+        "max": 29396
+      }
+    }
+  },
+  {
+    "contract": "test/DelegateProxyTest.sol:ProxiedContract",
+    "deployment": {
+      "gas": 106511,
+      "size": 276
+    },
+    "functions": {
+      "deposit(uint256)": {
+        "calls": 1,
+        "min": 3320,
+        "mean": 3320,
+        "median": 3320,
+        "max": 3320
+      }
+    }
+  }
+]
+"#]]
+            .is_json(),
+        );
 });