test: Add and update UCI engine output tests

- Update `TestInit` in `uci/engine_test.go` to use `out` instead of `in` for expected output source
- Add `TestPrint` test to validate output generation of a custom message ("Hello, World!")
- Add `TestCopyProtection` test to ensure `CopyProtection` method outputs "copyprotection ok"

[uci/engine_test.go]
- Replaced `in` with `out` in the `TestInit` function to align with the expected output source.
- Added a new `TestPrint` function to test output generation for a custom message ("Hello, World!").
- Added a new `TestCopyProtection` function to verify the output of the `CopyProtection` method, ensuring it produces "copyprotection ok".

uci/engine_test.go

@@ -2,6 +2,7 @@ package uci
 
 import (
 	"io"
+	"strings"
 	"testing"
 )
 
@@ -13,22 +14,48 @@ func base() (Engine, io.Reader, io.Writer) {
 }
 
 func TestInit(t *testing.T) {
-	e, in, _ := base()
+	e, out, _ := base()
 
 	go e.Init()
 
-	buf := make([]byte, 1024)
-	n, err := in.Read(buf)
+	expectLine(t, out, "id name GoChess2")
+	expectLine(t, out, "id author MS")
+	expectLine(t, out, "uciok")
+}
 
+func TestPrint(t *testing.T) {
+	e, out, _ := base()
+
+	go e.Print("Hello, World!")
+
+	expectLine(t, out, "Hello, World!")
+}
+
+func TestCopyProtection(t *testing.T) {
+	e, out, _ := base()
+
+	go e.CopyProtection()
+
+	expectLine(t, out, "copyprotection ok")
+}
+
+func expectLine(t *testing.T, in io.Reader, expected string) {
+	line, err := readLine(in)
 	if err != nil {
-		t.Error(err)
+		t.Fatalf("Error reading line: %v", err)
 	}
 
-	if n == 0 {
-		t.Error("No data read")
-	}
-
-	if string(buf[:n]) != "id name GoChess2\n" {
-		t.Error("Unexpected output, got:", string(buf[:n]))
+	if line != expected {
+		t.Fatalf("Expected '%s', got '%s'", expected, line)
 	}
 }
+
+func readLine(in io.Reader) (string, error) {
+	buf := make([]byte, 1024)
+	n, err := in.Read(buf)
+	if err != nil {
+		return "", err
+	}
+
+	return strings.Trim(string(buf[:n]), "\n"), nil
+}