op-bindings: Check for duplicate artifacts

Checks for duplicate artifacts when instantiating the `hardhat` object. This armors against an issue in the regentool where the regentool was passing in the deployments directory rather than the network directory. This led to artifacts being non-deterministically chosen based on however `fs.WalkDir` iterated over the deployments directory.

Fixes ENG-3054

op-bindings/hardhat/hardhat.go

@@ -76,6 +76,7 @@ func (h *Hardhat) init() error {
 // initDeployments reads all of the deployment json files from disk and then
 // caches the deserialized `Deployment` structs.
 func (h *Hardhat) initDeployments() error {
+	knownDeployments := make(map[string]string)
 	for _, deploymentPath := range h.DeploymentPaths {
 		fileSystem := os.DirFS(filepath.Join(deploymentPath, h.network))
 		err := fs.WalkDir(fileSystem, ".", func(path string, d fs.DirEntry, err error) error {
@@ -103,7 +104,16 @@ func (h *Hardhat) initDeployments() error {
 			}
 
 			deployment.Name = filepath.Base(name[:len(name)-5])
+			if knownDeployments[deployment.Name] != "" {
+				return fmt.Errorf(
+					"discovered duplicate deployment %s. old: %s, new: %s",
+					deployment.Name,
+					knownDeployments[deployment.Name],
+					name,
+				)
+			}
 			h.deployments = append(h.deployments, &deployment)
+			knownDeployments[deployment.Name] = name
 			return nil
 		})
 		if err != nil {

op-bindings/hardhat/hardhat_test.go

@@ -146,6 +146,20 @@ func TestHardhatGetDeployments(t *testing.T) {
 	require.NotNil(t, deployment)
 }
 
+func TestHardhatGetDeploymentsDuplicates(t *testing.T) {
+	t.Parallel()
+
+	// Set the network to an empty string to simulate
+	// an invalid network name.
+	_, err := hardhat.New(
+		"",
+		[]string{"testdata/artifacts"},
+		[]string{"testdata/deployments"},
+	)
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "duplicate deployment")
+}
+
 func TestHardhatGetStorageLayout(t *testing.T) {
 	t.Parallel()