refactor: use errors.Is instead of string parsing in isEngineIncompatibleError

Replace fragile string parsing with errors.Is check using the exported
ErrNoDriver sentinel error from the constraint framework. This is more
robust and won't break if error messages change in the framework.

Signed-off-by: Sertac Ozercan <[email protected]>

Author: sozercan

pkg/gator/bench/bench.go

@@ -2,16 +2,17 @@ package bench
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"runtime"
-	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
 
 	"github.com/open-policy-agent/frameworks/constraint/pkg/apis"
 	constraintclient "github.com/open-policy-agent/frameworks/constraint/pkg/client"
 	"github.com/open-policy-agent/frameworks/constraint/pkg/client/drivers/rego"
+	clienterrors "github.com/open-policy-agent/frameworks/constraint/pkg/client/errors"
 	"github.com/open-policy-agent/frameworks/constraint/pkg/client/reviews"
 	"github.com/open-policy-agent/gatekeeper/v3/pkg/drivers/k8scel"
 	"github.com/open-policy-agent/gatekeeper/v3/pkg/gator/reader"
@@ -346,20 +347,9 @@ func isEngineIncompatibleError(err error) bool {
 	if err == nil {
 		return false
 	}
-	errStr := err.Error()
-	// CEL engine returns this error when no CEL code block is present
-	if strings.Contains(errStr, "no CEL code") ||
-		strings.Contains(errStr, "missing CEL source") ||
-		strings.Contains(errStr, "No language driver is installed") ||
-		strings.Contains(errStr, "no validator for driver") {
-		return true
-	}
-	// Rego engine returns this error when no Rego code block is present
-	if strings.Contains(errStr, "no Rego code") ||
-		strings.Contains(errStr, "missing Rego source") {
-		return true
-	}
-	return false
+	// Use errors.Is to check for the sentinel error from the constraint framework.
+	// This is more robust than string matching and won't break if error messages change.
+	return errors.Is(err, clienterrors.ErrNoDriver)
 }
 
 // runSequentialBenchmark runs the benchmark sequentially (single-threaded).

pkg/gator/bench/bench_test.go

@@ -2,10 +2,13 @@ package bench
 
 import (
 	"bytes"
+	"fmt"
 	"os"
 	"path/filepath"
 	"strings"
 	"testing"
+
+	clienterrors "github.com/open-policy-agent/frameworks/constraint/pkg/client/errors"
 )
 
 func TestRun_MissingInputs(t *testing.T) {
@@ -667,33 +670,18 @@ func TestIsEngineIncompatibleError(t *testing.T) {
 			expected: false,
 		},
 		{
-			name:     "no CEL code error",
-			err:      &testError{msg: "no CEL code found"},
-			expected: true,
-		},
-		{
-			name:     "no language driver error",
-			err:      &testError{msg: "No language driver is installed"},
-			expected: true,
-		},
-		{
-			name:     "no Rego code error",
-			err:      &testError{msg: "no Rego code found"},
-			expected: true,
-		},
-		{
-			name:     "missing CEL source error",
-			err:      &testError{msg: "missing CEL source"},
+			name:     "ErrNoDriver directly",
+			err:      clienterrors.ErrNoDriver,
 			expected: true,
 		},
 		{
-			name:     "missing Rego source error",
-			err:      &testError{msg: "missing Rego source"},
+			name:     "ErrNoDriver wrapped",
+			err:      fmt.Errorf("constraint template error: %w", clienterrors.ErrNoDriver),
 			expected: true,
 		},
 		{
-			name:     "no validator for driver error",
-			err:      &testError{msg: "no validator for driver"},
+			name:     "ErrNoDriver double wrapped",
+			err:      fmt.Errorf("outer: %w", fmt.Errorf("inner: %w", clienterrors.ErrNoDriver)),
 			expected: true,
 		},
 		{

pkg/gator/bench/compare_test.go

@@ -419,5 +419,3 @@ func TestFormatComparison_WithRegression(t *testing.T) {
 		}
 	}
 }
-
-