allow external functions to optionally act on evaluation result.

Signed-off-by: Pushpalanka Jayawardhana <pushpalanka.jayawardhana@zalando.de>

envoyauth/response.go

@@ -35,13 +35,20 @@ type StopFunc = func()
 type TransactionCloser func(ctx context.Context, err error) error
 
 // NewEvalResult creates a new EvalResult and a StopFunc that is used to stop the timer for metrics
-func NewEvalResult() (*EvalResult, StopFunc, error) {
+func NewEvalResult(opts ...func(*EvalResult)) (*EvalResult, StopFunc, error) {
 	var err error
 
-	er := EvalResult{
+	er := &EvalResult{
 		Metrics: metrics.New(),
 	}
-	er.DecisionID, err = util.UUID4()
+
+	for _, opt := range opts {
+		opt(er)
+	}
+
+	if er.DecisionID == "" {
+		er.DecisionID, err = util.UUID4()
+	}
 
 	if err != nil {
 		return nil, nil, err
@@ -53,7 +60,7 @@ func NewEvalResult() (*EvalResult, StopFunc, error) {
 		_ = er.Metrics.Timer(metrics.ServerHandler).Stop()
 	}
 
-	return &er, stop, nil
+	return er, stop, nil
 }
 
 // GetTxn creates a read transaction suitable for the configured EvalResult object

envoyauth/response_test.go

@@ -396,3 +396,23 @@ func TestGetDynamicMetadataWithBooleanDecision(t *testing.T) {
 		t.Fatalf("Expected no result but got %v", result)
 	}
 }
+
+func TestNewEvalResultWithDecisionID(t *testing.T) {
+	type Opt func(*EvalResult)
+
+	withDecisionID := func(decisionID string) Opt {
+		return func(result *EvalResult) {
+			result.DecisionID = decisionID
+		}
+	}
+
+	expectedDecisionID := "some-decision-id"
+
+	er, _, err := NewEvalResult(withDecisionID(expectedDecisionID))
+	if err != nil {
+		t.Fatalf("NewEvalResult() error = %v, wantErr %v", err, false)
+	}
+	if er.DecisionID != expectedDecisionID {
+		t.Errorf("Expected DecisionID to be '%v', got '%v'", expectedDecisionID, er.DecisionID)
+	}
+}