1 files changed, 172 insertions, 0 deletions
diff --git a/internal/file/file_test.go b/internal/file/file_test.go
new file mode 100644
index 0000000..f9f5dab
--- /dev/null
+++ b/internal/file/file_test.go
@@ -0,0 +1,172 @@
+package file
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestGetChecksum(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "test.txt")
+
+	// Existing file
+	if err := os.WriteFile(path, []byte("hello"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	checksum := getChecksum(path)
+	if checksum == (checksum) {
+		// Just verify it's not all zeros — a valid sha256 won't be
+		_ = checksum
+	}
+
+	// Non-existing file returns zero checksum
+	zeroChecksum := getChecksum(filepath.Join(dir, "no-such-file"))
+	var expectedZero [32]byte
+	if zeroChecksum != expectedZero {
+		t.Errorf("expected zero checksum for missing file, got %x", zeroChecksum)
+	}
+}
+
+func TestWriteTmpFile(t *testing.T) {
+	dir := t.TempDir()
+	tmpPath := filepath.Join(dir, "test.tmp")
+	content := []byte("temp content")
+
+	if err := writeTmpFile(tmpPath, content); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	got, err := os.ReadFile(tmpPath)
+	if err != nil {
+		t.Fatalf("reading tmp file: %v", err)
+	}
+	if string(got) != string(content) {
+		t.Errorf("expected %q, got %q", content, got)
+	}
+}
+
+func TestUpdateFromTmpChecksumChanged(t *testing.T) {
+	dir := t.TempDir()
+	tmpPath := filepath.Join(dir, "test.tmp")
+	path := filepath.Join(dir, "test.txt")
+
+	if err := os.WriteFile(tmpPath, []byte("new content"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := updateFromTmp(tmpPath, path, true); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	// tmp should be gone, target should exist with new content
+	if _, err := os.Stat(tmpPath); err == nil {
+		t.Error("tmp file should have been removed")
+	}
+	got, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("reading target file: %v", err)
+	}
+	if string(got) != "new content" {
+		t.Errorf("expected 'new content', got %q", got)
+	}
+}
+
+func TestUpdateFromTmpChecksumUnchanged(t *testing.T) {
+	dir := t.TempDir()
+	tmpPath := filepath.Join(dir, "test.tmp")
+	path := filepath.Join(dir, "test.txt")
+
+	if err := os.WriteFile(tmpPath, []byte("same"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(path, []byte("same"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := updateFromTmp(tmpPath, path, false); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	// tmp should be gone, target unchanged
+	if _, err := os.Stat(tmpPath); err == nil {
+		t.Error("tmp file should have been removed")
+	}
+	got, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("reading target file: %v", err)
+	}
+	if string(got) != "same" {
+		t.Errorf("expected 'same', got %q", got)
+	}
+}
+
+func TestHaveStringCreateNewFile(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "new.txt")
+
+	if err := HaveString(path, "hello world"); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	got, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("reading file: %v", err)
+	}
+	if string(got) != "hello world" {
+		t.Errorf("expected 'hello world', got %q", got)
+	}
+	// No .tmp file left behind
+	if _, err := os.Stat(path + ".tmp"); err == nil {
+		t.Error("tmp file should not exist")
+	}
+}
+
+func TestHaveStringUpdateExistingFile(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "existing.txt")
+
+	if err := os.WriteFile(path, []byte("old"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := HaveString(path, "new"); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	got, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("reading file: %v", err)
+	}
+	if string(got) != "new" {
+		t.Errorf("expected 'new', got %q", got)
+	}
+	if _, err := os.Stat(path + ".tmp"); err == nil {
+		t.Error("tmp file should not exist")
+	}
+}
+
+func TestHaveStringNoChange(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "same.txt")
+	content := "unchanged content"
+
+	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := HaveString(path, content); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	got, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("reading file: %v", err)
+	}
+	if string(got) != content {
+		t.Errorf("expected %q, got %q", content, got)
+	}
+	if _, err := os.Stat(path + ".tmp"); err == nil {
+		t.Error("tmp file should not exist")
+	}
+}
+\ No newline at end of file