Add extension normalization command

tests/contract/extension_validation_test.go

@@ -0,0 +1,102 @@
+package contract
+
+import (
+	"context"
+	"errors"
+	"path/filepath"
+	"testing"
+
+	"github.com/rogeecn/renamer/internal/extension"
+	"github.com/rogeecn/renamer/internal/listing"
+)
+
+func TestParseArgsValidation(t *testing.T) {
+	cases := []struct {
+		name string
+		args []string
+	}{
+		{"tooFew", []string{".jpg"}},
+		{"emptySource", []string{" ", ".jpg"}},
+		{"missingDotSource", []string{"jpg", ".png"}},
+		{"missingDotTarget", []string{".jpg", "png"}},
+	}
+
+	for _, tc := range cases {
+		_, err := extension.ParseArgs(tc.args)
+		if err == nil {
+			t.Fatalf("expected error for case %s", tc.name)
+		}
+	}
+
+	_, err := extension.ParseArgs([]string{".jpg", ".JPG"})
+	if err == nil {
+		t.Fatalf("expected error when all sources match target")
+	}
+
+	parsed, err := extension.ParseArgs([]string{".jpeg", ".JPG", ".jpg"})
+	if err != nil {
+		t.Fatalf("unexpected error for valid args: %v", err)
+	}
+	if len(parsed.SourcesCanonical) != 1 || parsed.SourcesCanonical[0] != ".jpeg" {
+		t.Fatalf("expected canonical list to contain .jpeg only, got %#v", parsed.SourcesCanonical)
+	}
+	if len(parsed.NoOps) != 1 {
+		t.Fatalf("expected .jpg to be treated as no-op")
+	}
+}
+
+func TestPreviewDetectsConflicts(t *testing.T) {
+	tmp := t.TempDir()
+	writeTestFile(t, filepath.Join(tmp, "report.jpeg"))
+	writeTestFile(t, filepath.Join(tmp, "report.jpg"))
+
+	scope := &listing.ListingRequest{
+		WorkingDir:         tmp,
+		IncludeDirectories: false,
+		Recursive:          false,
+		IncludeHidden:      false,
+		Format:             listing.FormatTable,
+	}
+	if err := scope.Validate(); err != nil {
+		t.Fatalf("validate scope: %v", err)
+	}
+
+	req := extension.NewRequest(scope)
+	parsed, err := extension.ParseArgs([]string{".jpeg", ".jpg"})
+	if err != nil {
+		t.Fatalf("parse error: %v", err)
+	}
+	req.SetExtensions(parsed.SourcesCanonical, parsed.SourcesDisplay, parsed.Target)
+	req.SetWarnings(parsed.Duplicates, parsed.NoOps)
+
+	summary, planned, err := extension.Preview(context.Background(), req, nil)
+	if err != nil {
+		t.Fatalf("preview error: %v", err)
+	}
+	if !summary.HasConflicts() {
+		t.Fatalf("expected conflict when target already exists")
+	}
+	if len(planned) != 0 {
+		t.Fatalf("expected no operations due to conflict, got %d", len(planned))
+	}
+	if len(summary.Warnings) == 0 {
+		t.Fatalf("expected warning recorded for conflict")
+	}
+
+	// Apply should be skipped by caller; invoking directly without operations should no-op.
+	req.SetExecutionMode(false, true)
+	entry, err := extension.Apply(context.Background(), req, planned, summary)
+	if err != nil {
+		t.Fatalf("apply error: %v", err)
+	}
+	if len(entry.Operations) != 0 {
+		t.Fatalf("expected zero operations recorded when conflicts present")
+	}
+
+	if _, err := extension.ParseArgs([]string{".jpeg", ".jpg"}); err != nil {
+		// ensure previous parse errors do not leak state
+		if !errors.Is(err, nil) {
+			// unreachable, but keeps staticcheck happy
+		}
+	}
+}