diff --git a/test/GPv2Signing.test.ts b/test/GPv2Signing.test.ts
deleted file mode 100644
index 5fa7be76..00000000
--- a/test/GPv2Signing.test.ts
+++ /dev/null
@@ -1,2 +0,0 @@
-// eslint-disable-next-line @typescript-eslint/no-empty-function
-describe("GPv2Signing", () => {});
diff --git a/test/GPv2Signing/CalldataManipulation.t.sol b/test/GPv2Signing/CalldataManipulation.t.sol
index c35feebb..a4829aaf 100644
--- a/test/GPv2Signing/CalldataManipulation.t.sol
+++ b/test/GPv2Signing/CalldataManipulation.t.sol
@@ -5,7 +5,7 @@ import {Vm} from "forge-std/Test.sol";
 
 import {GPv2Order, GPv2Signing, IERC20} from "src/contracts/mixins/GPv2Signing.sol";
 
-import {GPv2SigningTestInterface, Helper} from "./Helper.sol";
+import {Harness, Helper} from "./Helper.sol";
 
 import {Bytes} from "test/libraries/Bytes.sol";
 import {Order} from "test/libraries/Order.sol";
@@ -47,7 +47,7 @@ contract CalldataManipulation is Helper {
 
         IERC20[] memory tokens = encoder.tokens();
         bytes memory encodedTransactionData =
-            abi.encodeCall(GPv2SigningTestInterface.recoverOrderFromTradeTest, (tokens, encoder.trades[0]));
+            abi.encodeCall(Harness.recoverOrderFromTradeTest, (tokens, encoder.trades[0]));
 
         // calldata encoding:
         //  -  4 bytes: signature
diff --git a/test/GPv2Signing/Helper.sol b/test/GPv2Signing/Helper.sol
index 295b8880..994f38ed 100644
--- a/test/GPv2Signing/Helper.sol
+++ b/test/GPv2Signing/Helper.sol
@@ -3,15 +3,20 @@ pragma solidity ^0.8;
 
 import {Test} from "forge-std/Test.sol";
 
-import {GPv2Order} from "src/contracts/mixins/GPv2Signing.sol";
+import {GPv2Order, GPv2Signing, GPv2Trade, IERC20} from "src/contracts/mixins/GPv2Signing.sol";
 
 import {Sign} from "test/libraries/Sign.sol";
-import {GPv2SigningTestInterface} from "test/src/GPv2SigningTestInterface.sol";
 
-// TODO: move the content of `GPv2SigningTestInterface` here once all tests have
-// been removed.
-// solhint-disable-next-line no-empty-blocks
-contract Harness is GPv2SigningTestInterface {
+contract Harness is GPv2Signing {
+    function recoverOrderFromTradeTest(IERC20[] calldata tokens, GPv2Trade.Data calldata trade)
+        external
+        view
+        returns (GPv2Signing.RecoveredOrder memory recoveredOrder)
+    {
+        recoveredOrder = allocateRecoveredOrder();
+        recoverOrderFromTrade(recoveredOrder, tokens, trade);
+    }
+
     function recoverOrderSignerTest(GPv2Order.Data memory order, Sign.Signature calldata signature)
         public
         view
diff --git a/test/src/GPv2SigningTestInterface.sol b/test/src/GPv2SigningTestInterface.sol
deleted file mode 100644
index b0b20270..00000000
--- a/test/src/GPv2SigningTestInterface.sol
+++ /dev/null
@@ -1,27 +0,0 @@
-// SPDX-License-Identifier: LGPL-3.0-or-later
-// solhint-disable-next-line compiler-version
-pragma solidity >=0.7.6 <0.9.0;
-pragma abicoder v2;
-
-import "src/contracts/libraries/GPv2Order.sol";
-import "src/contracts/libraries/GPv2Trade.sol";
-import "src/contracts/mixins/GPv2Signing.sol";
-
-contract GPv2SigningTestInterface is GPv2Signing {
-    function recoverOrderFromTradeTest(IERC20[] calldata tokens, GPv2Trade.Data calldata trade)
-        external
-        view
-        returns (RecoveredOrder memory recoveredOrder)
-    {
-        recoveredOrder = allocateRecoveredOrder();
-        recoverOrderFromTrade(recoveredOrder, tokens, trade);
-    }
-
-    function recoverOrderSignerTest(
-        GPv2Order.Data memory order,
-        GPv2Signing.Scheme signingScheme,
-        bytes calldata signature
-    ) external view returns (address owner) {
-        (, owner) = recoverOrderSigner(order, signingScheme, signature);
-    }
-}