Add insert command

tests/integration/insert_validation_test.go

@@ -0,0 +1,55 @@
+package integration
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"testing"
+
+	renamercmd "github.com/rogeecn/renamer/cmd"
+)
+
+func TestInsertValidationConflictsBlockApply(t *testing.T) {
+	t.Parallel()
+
+	tmp := t.TempDir()
+	createInsertValidationFile(t, filepath.Join(tmp, "baseline.txt"))
+	createInsertValidationFile(t, filepath.Join(tmp, "baseline_MARKED.txt"))
+
+	var out bytes.Buffer
+	cmd := renamercmd.NewRootCommand()
+	cmd.SetOut(&out)
+	cmd.SetErr(&out)
+	cmd.SetArgs([]string{"insert", "$", "_MARKED", "--yes", "--path", tmp})
+
+	if err := cmd.Execute(); err == nil {
+		t.Fatalf("expected command to fail when conflicts present")
+	}
+}
+
+func TestInsertValidationInvalidPosition(t *testing.T) {
+	t.Parallel()
+
+	tmp := t.TempDir()
+	createInsertValidationFile(t, filepath.Join(tmp, "短.txt"))
+
+	var out bytes.Buffer
+	cmd := renamercmd.NewRootCommand()
+	cmd.SetOut(&out)
+	cmd.SetErr(&out)
+	cmd.SetArgs([]string{"insert", "50", "X", "--dry-run", "--path", tmp})
+
+	if err := cmd.Execute(); err == nil {
+		t.Fatalf("expected invalid position to produce error")
+	}
+}
+
+func createInsertValidationFile(t *testing.T, path string) {
+	t.Helper()
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		t.Fatalf("mkdir %s: %v", path, err)
+	}
+	if err := os.WriteFile(path, []byte("validation"), 0o644); err != nil {
+		t.Fatalf("write file %s: %v", path, err)
+	}
+}