1 files changed, 70 insertions, 0 deletions
diff --git a/internal/repl/commands_test.go b/internal/repl/commands_test.go
new file mode 100644
index 0000000..7a37579
--- /dev/null
+++ b/internal/repl/commands_test.go
@@ -0,0 +1,70 @@
+package repl
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestExecuteCommandHelp(t *testing.T) {
+	output, err := ExecuteCommand("help")
+	if err != nil {
+		t.Fatalf("ExecuteCommand('help') returned error: %v", err)
+	}
+	if output == "" {
+		t.Error("ExecuteCommand('help') returned empty output")
+	}
+	if !strings.Contains(output, "PERC") {
+		t.Errorf("ExecuteCommand('help') output should contain 'PERC', got: %s", output[:50])
+	}
+}
+
+func TestExecuteCommandHelpWithSubcommand(t *testing.T) {
+	output, err := ExecuteCommand("help clear")
+	if err != nil {
+		t.Fatalf("ExecuteCommand('help clear') returned error: %v", err)
+	}
+	if output == "" {
+		t.Error("ExecuteCommand('help clear') returned empty output")
+	}
+	if !strings.Contains(output, "Clear") {
+		t.Errorf("ExecuteCommand('help clear') output should contain 'Clear', got: %s", output[:50])
+	}
+}
+
+func TestExecuteCommandUnknownCommand(t *testing.T) {
+	_, err := ExecuteCommand("unknown")
+	if err == nil {
+		t.Error("ExecuteCommand('unknown') should return error, got nil")
+	}
+	if !strings.Contains(err.Error(), "unknown command") {
+		t.Errorf("Error should mention 'unknown command', got: %v", err)
+	}
+}
+
+func TestExecuteCommandClear(t *testing.T) {
+	_, err := ExecuteCommand("clear")
+	if err != nil {
+		t.Fatalf("ExecuteCommand('clear') returned error: %v", err)
+	}
+}
+
+func TestExecuteCommandQuit(t *testing.T) {
+	_, err := ExecuteCommand("quit")
+	if err != nil {
+		t.Fatalf("ExecuteCommand('quit') returned error: %v", err)
+	}
+}
+
+func TestExecuteCommandExit(t *testing.T) {
+	_, err := ExecuteCommand("exit")
+	if err != nil {
+		t.Fatalf("ExecuteCommand('exit') returned error: %v", err)
+	}
+}
+
+func TestExecuteCommandEmpty(t *testing.T) {
+	_, err := ExecuteCommand("")
+	if err != nil {
+		t.Fatalf("ExecuteCommand('') returned error: %v", err)
+	}
+}