Add int adapter.

test/Push3IntAdapter.t.sol

@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.20;
+
+import {Test} from "forge-std/Test.sol";
+import {Push3Interpreter} from "../src/Push3Interpreter.sol";
+import {Push3IntAdapter} from "../src/Push3IntAdapter.sol";
+
+/**
+ * @title Push3IntAdapterTest
+ * @dev Foundry test for the Push3IntAdapter contract, 
+ *      which composes with the Push3Interpreter.
+ */
+contract Push3IntAdapterTest is Test {
+    Push3Interpreter public interpreter;
+    Push3IntAdapter public adapter;
+
+    function setUp() public {
+        // 1) Deploy the interpreter
+        interpreter = new Push3Interpreter();
+
+        // 2) Deploy the adapter, referencing the interpreter address
+        adapter = new Push3IntAdapter(address(interpreter));
+    }
+
+    /**
+     * @notice Test run1In1Out with a minimal code array. 
+     * For example, we might do a program that just leaves its input unchanged 
+     * (like a NOOP). 
+     */
+    function test_run1In1Out_noop() public {
+        bytes memory code = hex"03000100";
+
+        int256 inputVal = 123;
+        int256 result = adapter.run1In1Out(code, inputVal);
+
+        // We expect the code does nothing => output == input
+        assertEq(result, inputVal, "Expected same value out");
+    }
+
+    /**
+     * @notice Test run2In1Out. We'll push 5, 7, do an op that leaves 12.
+     */
+    function test_run2In1Out_plus() public {
+        bytes memory code = hex"03000101";
+
+        int256 in1 = 5;
+        int256 in2 = 7;
+        int256 result = adapter.run2In1Out(code, in1, in2);
+        
+        assertEq(result, 12, "Expected 5 + 7 = 12");
+    }
+
+    /**
+     * @notice Test run1In2Out. Push a constant to a stack with 1.
+     * For now, we do a placeholder code. 
+     */
+    function test_run1In2Out() public {
+        bytes memory code = hex"0300050200000003";
+
+        int256 inVal = 42;
+        (int256 top, int256 secondTop) = adapter.run1In2Out(code, inVal);
+
+        assertEq(top, 3, "top stack val mismatch");
+        assertEq(secondTop, 42, "second top stack val mismatch");
+    }
+
+    /**
+     * @notice Test run0InNOut. 
+     * We'll feed a code that pushes some constants, and see the final stack.
+     */
+    function test_run0InNOut() public {
+        
+        bytes memory code = hex"03000A02000000030200000005";
+
+        int256[] memory stackResult = adapter.run0InNOut(code);
+
+        assertEq(stackResult.length, 2, "Expected 2 final stack items");
+        assertEq(stackResult[0], 3, "Item 0 mismatch");
+        assertEq(stackResult[1], 5, "Item 1 mismatch");
+    }
+}