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package showcase
import (
"os"
"path/filepath"
"testing"
)
// TestCopyFile_CopiesContent verifies the basic success path still works
// after copyFile was changed to use a named return so that a destination
// Close() error can be surfaced without changing the happy-path result.
func TestCopyFile_CopiesContent(t *testing.T) {
t.Parallel()
dir := t.TempDir()
src := filepath.Join(dir, "source.txt")
dst := filepath.Join(dir, "dest.txt")
want := "hello showcase\n"
if err := os.WriteFile(src, []byte(want), 0644); err != nil {
t.Fatalf("failed to write source file: %v", err)
}
if err := copyFile(src, dst); err != nil {
t.Fatalf("copyFile() returned error: %v", err)
}
got, err := os.ReadFile(dst)
if err != nil {
t.Fatalf("failed to read destination file: %v", err)
}
if string(got) != want {
t.Fatalf("copyFile() wrote %q, want %q", string(got), want)
}
}
// TestCopyFile_MissingSourceReturnsError verifies that a missing source file
// still produces an error (and never a nil error masked by the deferred
// destination-close handling) and does not leave a destination file behind.
func TestCopyFile_MissingSourceReturnsError(t *testing.T) {
t.Parallel()
dir := t.TempDir()
src := filepath.Join(dir, "does-not-exist.txt")
dst := filepath.Join(dir, "dest.txt")
err := copyFile(src, dst)
if err == nil {
t.Fatal("copyFile() with missing source returned nil error, want non-nil")
}
if _, statErr := os.Stat(dst); statErr == nil {
t.Fatal("copyFile() with missing source created a destination file, want none")
}
}
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