Added tests for JSON format (#4248).

src.ts/_tests/test-abi.ts

@@ -151,8 +151,26 @@ describe("Test Interface", function() {
         assert.equal(log.args[0], "0x8ba1f109551bD432803012645Ac136ddd64DBA72");
         assert.equal(log.args[1], "0xAC1639CF97a3A46D431e6d1216f576622894cBB5");
         assert.equal(log.args[2], BigInt(234));
+
+    });
+
+    // See #4248
+    it("formats JSON ABI parameters with default empty string for `name` key", function() {
+        assert.deepEqual(JSON.parse(iface.getFunction("balanceOf")!.format('json')), {
+            constant: false,
+            inputs: [
+                { name: "owner", type: "address" }
+            ],
+            name: "balanceOf",
+            outputs: [
+                { name: "", type: "uint256" }
+            ],
+            payable: false,
+            type: "function",
         });
     });
+});
+
 
 describe("Tests Legacy ABI formats", function() {