1 files changed, 189 insertions, 0 deletions
diff --git a/internal/resource/link/link_test.go b/internal/resource/link/link_test.go
new file mode 100644
index 0000000..8da674b
--- /dev/null
+++ b/internal/resource/link/link_test.go
@@ -0,0 +1,189 @@
+package link
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestHaveSymlinkCreateAndIdempotent(t *testing.T) {
+	dir := t.TempDir()
+	target := filepath.Join(dir, "target.txt")
+	link := filepath.Join(dir, "link.txt")
+	if err := os.WriteFile(target, []byte("t"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	Have(link, IsSymlink(target))
+	got, err := os.Readlink(link)
+	if err != nil {
+		t.Fatalf("readlink: %v", err)
+	}
+	if got != target {
+		t.Errorf("expected link -> %s, got %s", target, got)
+	}
+
+	// Re-applying the same link should be a no-op (tested directly to avoid the
+	// one-per-process resource registry rejecting a duplicate registration).
+	l := &Link{path: link, kind: symlinkKind, target: target}
+	if err := ensureSymlink(l); err != nil {
+		t.Fatalf("idempotent apply: %v", err)
+	}
+}
+
+func TestHaveSymlinkRepoints(t *testing.T) {
+	dir := t.TempDir()
+	old := filepath.Join(dir, "old.txt")
+	newT := filepath.Join(dir, "new.txt")
+	link := filepath.Join(dir, "link")
+	for _, p := range []string{old, newT} {
+		if err := os.WriteFile(p, []byte("x"), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if err := os.Symlink(old, link); err != nil {
+		t.Fatal(err)
+	}
+
+	Have(link, IsSymlink(newT))
+	got, err := os.Readlink(link)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got != newT {
+		t.Errorf("expected repoint to %s, got %s", newT, got)
+	}
+}
+
+func TestHaveSymlinkMovesRealFileAside(t *testing.T) {
+	dir := t.TempDir()
+	target := filepath.Join(dir, "target.txt")
+	link := filepath.Join(dir, "real")
+	if err := os.WriteFile(target, []byte("t"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(link, []byte("original"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	Have(link, IsSymlink(target))
+
+	got, err := os.Readlink(link)
+	if err != nil {
+		t.Fatalf("expected %s to be a symlink: %v", link, err)
+	}
+	if got != target {
+		t.Errorf("expected link -> %s, got %s", target, got)
+	}
+	if data, err := os.ReadFile(link + ".old"); err != nil || string(data) != "original" {
+		t.Errorf("expected original content preserved in %s.old, got %q err %v", link, string(data), err)
+	}
+}
+
+func TestHaveHardlinkCreateAndIdempotent(t *testing.T) {
+	dir := t.TempDir()
+	target := filepath.Join(dir, "target.txt")
+	link := filepath.Join(dir, "link.txt")
+	if err := os.WriteFile(target, []byte("payload"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	Have(link, IsHardlink(target))
+
+	ti, err := os.Stat(target)
+	if err != nil {
+		t.Fatal(err)
+	}
+	li, err := os.Stat(link)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !sameInode(ti, li) {
+		t.Errorf("expected %s and %s to share an inode", link, target)
+	}
+
+	// Re-applying the same link should be a no-op (direct call to avoid the
+	// one-per-process resource registry rejecting a duplicate registration).
+	l := &Link{path: link, kind: hardlinkKind, target: target}
+	if err := ensureHardlink(l); err != nil {
+		t.Fatalf("idempotent apply: %v", err)
+	}
+}
+
+func TestHaveHardlinkMovesRealFileAside(t *testing.T) {
+	dir := t.TempDir()
+	target := filepath.Join(dir, "target.txt")
+	link := filepath.Join(dir, "real")
+	if err := os.WriteFile(target, []byte("payload"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(link, []byte("original"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	Have(link, IsHardlink(target))
+
+	ti, err := os.Stat(target)
+	if err != nil {
+		t.Fatal(err)
+	}
+	li, err := os.Stat(link)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !sameInode(ti, li) {
+		t.Errorf("expected %s to be hardlinked to %s", link, target)
+	}
+	if data, err := os.ReadFile(link + ".old"); err != nil || string(data) != "original" {
+		t.Errorf("expected original content preserved in %s.old, got %q err %v", link, string(data), err)
+	}
+}
+
+func TestHaveHardlinkMissingTarget(t *testing.T) {
+	dir := t.TempDir()
+	link := filepath.Join(dir, "link")
+	if err := Ensure(link, IsHardlink(filepath.Join(dir, "nope"))); err == nil {
+		t.Error("expected error when hardlink target does not exist")
+	}
+}
+
+func TestHaveAbsentSymlink(t *testing.T) {
+	dir := t.TempDir()
+	target := filepath.Join(dir, "target.txt")
+	link := filepath.Join(dir, "link.txt")
+	if err := os.WriteFile(target, []byte("t"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Symlink(target, link); err != nil {
+		t.Fatal(err)
+	}
+
+	Have(link, IsAbsent())
+	if _, err := os.Lstat(link); !os.IsNotExist(err) {
+		t.Errorf("expected %s to be removed", link)
+	}
+
+	// Idempotent: removing a missing link is not an error (direct call to
+	// avoid duplicate registration in the one-per-process registry).
+	if err := ensureAbsent(link); err != nil {
+		t.Fatalf("absent on missing link: %v", err)
+	}
+}
+
+func TestHaveAbsentWithoutKindRegistersGenericLink(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "whatever")
+
+	l := build(path, IsAbsent())
+	if got := l.resourceType(); got != "Link" {
+		t.Errorf("expected generic resource type %q, got %q", "Link", got)
+	}
+}
+
+func TestBuildRequiresKindOrAbsent(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "nope")
+	if err := Ensure(path); err == nil {
+		t.Error("expected error when neither IsSymlink, IsHardlink, nor IsAbsent is set")
+	}
+}