Add --group flag to override group name for stdin input

acceptance.bats

@@ -530,3 +530,30 @@ EOF"
   [ "$status" -eq 1 ]
   [[ "$output" =~ "10 tests, 3 passed, 0 warnings, 7 failures, 0 exceptions" ]]
 }
+
+@test "File name override flag replaces stdin filename in output" {
+  run bash -c "./conftest test --file-name-override='my-custom-file.yaml' -p examples/kubernetes/policy - < examples/kubernetes/service.yaml"
+  [ "$status" -eq 0 ]
+  [[ "$output" =~ "my-custom-file.yaml" ]]
+  [[ ! "$output" =~ "-" ]]
+}
+
+@test "File name override flag does not affect regular files" {
+  run ./conftest test --file-name-override='override.yaml' -p examples/kubernetes/policy examples/kubernetes/service.yaml
+  [ "$status" -eq 0 ]
+  [[ "$output" =~ "examples/kubernetes/service.yaml" ]]
+  [[ ! "$output" =~ "override.yaml" ]]
+}
+
+@test "File name override flag works with JSON output" {
+  run bash -c "./conftest test --file-name-override='custom.json' --output json -p examples/kubernetes/policy - < examples/kubernetes/service.yaml"
+  [ "$status" -eq 0 ]
+  [[ "$output" =~ "\"filename\":\"custom.json\"" ]]
+  [[ ! "$output" =~ "\"filename\":\"-\"" ]]
+}
+
+@test "Without file name override flag, stdin shows as dash" {
+  run bash -c "./conftest test -p examples/kubernetes/policy - < examples/kubernetes/service.yaml"
+  [ "$status" -eq 0 ]
+  [[ "$output" =~ "-" ]]
+}

internal/commands/test.go

@@ -115,6 +115,7 @@ func NewTestCommand(ctx context.Context) *cobra.Command {
 				"junit-hide-message",
 				"quiet",
 				"tls",
+				"file-name-override",
 			}
 			for _, name := range flagNames {
 				if err := viper.BindPFlag(name, cmd.Flags().Lookup(name)); err != nil {
@@ -196,6 +197,7 @@ func NewTestCommand(ctx context.Context) *cobra.Command {
 
 	cmd.Flags().StringSlice("proto-file-dirs", []string{}, "A list of directories containing Protocol Buffer definitions")
 	cmd.Flags().Bool("tls", true, "Use TLS to access the registry")
+	cmd.Flags().String("file-name-override", "", "Override the file name for stdin input (used for output formatting)")
 
 	return &cmd
 }

runner/test.go

@@ -35,6 +35,7 @@ type TestRunner struct {
 	Combine            bool
 	Quiet              bool
 	Output             string
+	FileNameOverride   string `mapstructure:"file-name-override"`
 }
 
 // Run executes the TestRunner, verifying all Rego policies against the given
@@ -110,6 +111,15 @@ func (t *TestRunner) Run(ctx context.Context, fileList []string) (output.CheckRe
 		}
 	}
 
+	// Override file name for stdin input if --file-name-override flag is provided
+	if t.FileNameOverride != "" {
+		for i := range results {
+			if results[i].FileName == "-" {
+				results[i].FileName = t.FileNameOverride
+			}
+		}
+	}
+
 	return results, nil
 }
 

runner/test_test.go

@@ -0,0 +1,155 @@
+package runner
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestTestRunner_FileNameOverrideFlag(t *testing.T) {
+	// Create a temporary directory for test files
+	tmpDir := t.TempDir()
+
+	// Create a test policy file
+	policyDir := filepath.Join(tmpDir, "policy")
+	if err := os.Mkdir(policyDir, 0755); err != nil {
+		t.Fatalf("Failed to create policy directory: %v", err)
+	}
+
+	policyContent := `package main
+
+deny contains msg if {
+	input.kind == "Deployment"
+	input.metadata.name == "test"
+	msg := "test deployment found"
+}
+`
+	policyFile := filepath.Join(policyDir, "test.rego")
+	if err := os.WriteFile(policyFile, []byte(policyContent), 0644); err != nil {
+		t.Fatalf("Failed to write policy file: %v", err)
+	}
+
+	// Test cases
+	tests := []struct {
+		name             string
+		fileNameOverride string
+		expectedFileName string
+	}{
+		{
+			name:             "with file-name-override",
+			fileNameOverride: "my-custom-file.yaml",
+			expectedFileName: "my-custom-file.yaml",
+		},
+		{
+			name:             "without file-name-override",
+			fileNameOverride: "",
+			expectedFileName: "-",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			// Create TestRunner with FileNameOverride set
+			runner := TestRunner{
+				Policy:           []string{policyDir},
+				Namespace:        []string{"main"},
+				FileNameOverride: tc.fileNameOverride,
+				RegoVersion:      "v1",
+			}
+
+			// Create stdin input by using "-" as the file path
+			fileList := []string{"-"}
+
+			// Mock stdin with test data
+			oldStdin := os.Stdin
+			r, w, _ := os.Pipe()
+			os.Stdin = r
+			testInput := `{
+	"apiVersion": "apps/v1",
+	"kind": "Deployment",
+	"metadata": {
+		"name": "test"
+	}
+}`
+			w.Write([]byte(testInput))
+			w.Close()
+			defer func() { os.Stdin = oldStdin }()
+
+			// Run the test
+			ctx := t.Context()
+			results, err := runner.Run(ctx, fileList)
+			if err != nil {
+				t.Fatalf("Run failed: %v", err)
+			}
+
+			// Verify results
+			if len(results) == 0 {
+				t.Fatal("Expected at least one result")
+			}
+
+			// Check that the filename was properly overridden
+			if results[0].FileName != tc.expectedFileName {
+				t.Errorf("Expected filename to be '%s', got '%s'", tc.expectedFileName, results[0].FileName)
+			}
+		})
+	}
+}
+
+func TestTestRunner_FileNameOverrideOnlyAffectsStdin(t *testing.T) {
+	// Create a temporary directory for test files
+	tmpDir := t.TempDir()
+
+	// Create a test policy file
+	policyDir := filepath.Join(tmpDir, "policy")
+	if err := os.Mkdir(policyDir, 0755); err != nil {
+		t.Fatalf("Failed to create policy directory: %v", err)
+	}
+
+	policyContent := `package main
+
+deny contains msg if {
+	input.kind == "Deployment"
+	msg := "deployment found"
+}
+`
+	policyFile := filepath.Join(policyDir, "test.rego")
+	if err := os.WriteFile(policyFile, []byte(policyContent), 0644); err != nil {
+		t.Fatalf("Failed to write policy file: %v", err)
+	}
+
+	// Create a test config file
+	configContent := `apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: test-file
+`
+	configFile := filepath.Join(tmpDir, "deployment.yaml")
+	if err := os.WriteFile(configFile, []byte(configContent), 0644); err != nil {
+		t.Fatalf("Failed to write config file: %v", err)
+	}
+
+	// Create TestRunner with FileNameOverride set
+	runner := TestRunner{
+		Policy:           []string{policyDir},
+		Namespace:        []string{"main"},
+		FileNameOverride: "overridden-name.yaml",
+		RegoVersion:      "v1",
+	}
+
+	// Run with a regular file (not stdin)
+	ctx := t.Context()
+	results, err := runner.Run(ctx, []string{configFile})
+	if err != nil {
+		t.Fatalf("Run failed: %v", err)
+	}
+
+	// Verify results
+	if len(results) == 0 {
+		t.Fatal("Expected at least one result")
+	}
+
+	// Check that the regular file name was NOT overridden
+	if results[0].FileName != configFile {
+		t.Errorf("Expected filename to remain '%s', got '%s'", configFile, results[0].FileName)
+	}
+}