Fix: address policy checker review feedback

pkg/plugin/implementation/opapolicychecker/cmd/plugin_test.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"context"
+	"path/filepath"
+	"testing"
+)
+
+func TestProviderNewSuccess(t *testing.T) {
+	provider := provider{}
+	config := map[string]string{
+		"type":     "file",
+		"location": filepath.Join("..", "testdata", "example.rego"),
+		"query":    "data.policy.result",
+	}
+
+	checker, closer, err := provider.New(context.Background(), config)
+	if err != nil {
+		t.Fatalf("New() unexpected error: %v", err)
+	}
+	if checker == nil {
+		t.Fatal("New() returned nil checker")
+	}
+	if closer == nil {
+		t.Fatal("New() returned nil closer")
+	}
+
+	closer()
+}
+
+func TestProviderNewFailure(t *testing.T) {
+	provider := provider{}
+
+	_, _, err := provider.New(context.Background(), map[string]string{
+		"type":  "file",
+		"query": "data.policy.result",
+	})
+	if err == nil {
+		t.Fatal("expected error when required config is missing")
+	}
+}