1 files changed, 17 insertions, 0 deletions
diff --git a/internal/net/iac_test.go b/internal/net/iac_test.go
new file mode 100644
index 0000000..71570db
--- /dev/null
+++ b/internal/net/iac_test.go
@@ -0,0 +1,17 @@
+package net
+
+import "testing"
+
+// Regression: stripIAC required a third byte, so a trailing 2-byte IAC command
+// leaked its option byte into player input.
+func TestStripIACDropsTruncatedSequence(t *testing.T) {
+	got := stripIAC("abc" + string([]byte{iac, 0xf1}))
+	if got != "abc" {
+		t.Fatalf("stripIAC(truncated) = %q, want %q", got, "abc")
+	}
+	// A full subnegotiation is still removed.
+	got = stripIAC("x" + string([]byte{iac, sb, 1, 2}) + string([]byte{iac, se}) + "y")
+	if got != "xy" {
+		t.Fatalf("stripIAC(subnegotiation) = %q, want xy", got)
+	}
+}