verbose toggle prints when on

  when the verbose flag is given then it prints
  trace information.
  when the verbose flag is false, then it
  does not print trace information

  this fixes issue:
  #5

Author: xchapter7x

pkg/commands/eval.go

@@ -50,11 +50,14 @@ func (s *EvalCommand) Execute(args []string) error {
 }
 
 func (s *EvalCommand) setDefaults() {
-	s.Writer = new(bytes.Buffer)
-	if s.Verbose {
+	if s.Writer == nil {
 		s.Writer = os.Stdout
 	}
 
+	if !s.Verbose {
+		s.Writer = new(bytes.Buffer)
+	}
+
 	if s.Namespace == "" {
 		s.Namespace = "main"
 	}

pkg/commands/eval_test.go

@@ -18,6 +18,7 @@ func TestEvalCommand(t *testing.T) {
 			policy    string
 			failsWith error
 			skip      bool
+			verbose   bool
 		}{
 			{
 				name:      "invalid policy path given",
@@ -130,6 +131,22 @@ func TestEvalCommand(t *testing.T) {
 				policy:    "testdata/policy/individuals/no_passing_valid.rego",
 				failsWith: commands.PolicyFailure,
 			},
+			{
+				name:      "verbosity on success should print trace information",
+				template:  "testdata/templates",
+				values:    []string{"testdata/values.yml", "testdata/added_values.yml"},
+				policy:    "testdata/policy/individuals/multiple_values.rego",
+				failsWith: nil,
+				verbose:   true,
+			},
+			{
+				name:      "verbosity on failure should print trace information",
+				template:  "testdata/templates",
+				values:    []string{"testdata/values.yml"},
+				policy:    "testdata/policy/individuals/no_passing_valid.rego",
+				failsWith: commands.PolicyFailure,
+				verbose:   true,
+			},
 		} {
 			t.Run(tt.name, func(t *testing.T) {
 				if tt.skip {
@@ -142,12 +159,21 @@ func TestEvalCommand(t *testing.T) {
 					Template: tt.template,
 					Policy:   tt.policy,
 					Values:   tt.values,
+					Verbose:  tt.verbose,
 				}
 				err := evalCmd.Execute([]string{})
 				if err != nil && !errors.Is(err, tt.failsWith) {
 					t.Errorf("expected error:\n%v\ngot:\n%v", tt.failsWith, err)
 				}
 
+				if !tt.verbose && stdOut.Len() > 0 {
+					t.Errorf("when verbose is off this should always be empty, but it contains %v bytes", stdOut.Len())
+				}
+
+				if tt.verbose && stdOut.Len() == 0 {
+					t.Errorf("we expected to print verbose trace information, but it is empty")
+				}
+
 				if err == nil && tt.failsWith != nil {
 					t.Errorf("expected a failing policy %w but no failures found", tt.failsWith)
 				}

pkg/commands/util.go

@@ -203,7 +203,6 @@ func getQueryList(policy string) map[string]int {
 }
 
 func evalPolicyOnInput(writer io.Writer, policy string, namespace string, input interface{}) error {
-	bufWriter := new(bytes.Buffer)
 	testResults := make(map[string]bool)
 	ctx := context.Background()
 	var results rego.ResultSet
@@ -244,9 +243,9 @@ func evalPolicyOnInput(writer io.Writer, policy string, namespace string, input
 
 		if len(resultSet) > 0 {
 			results = append(results, resultSet...)
-			topdown.PrettyTrace(bufWriter, *buf)
-			fmt.Fprint(writer, bufWriter.String())
 		}
+
+		topdown.PrettyTrace(writer, *buf)
 	}
 
 	if len(queryList) <= 0 {