1 files changed, 100 insertions, 0 deletions
diff --git a/terminal_test.go b/terminal_test.go
new file mode 100644
index 0000000..b0686ed
--- /dev/null
+++ b/terminal_test.go
@@ -0,0 +1,100 @@
+package main
+
+import (
+	"slices"
+	"testing"
+)
+
+// This could be way more extensive, but we're not aiming for perfection.
+var tests = []struct {
+	push, want string
+}{
+	{
+		// Escaping and UTF-8.
+		"\x03\x1bž\bř",
+		"^C^[ř\n",
+	},
+	{
+		// Several kinds of sequences to be ignored.
+		"\x1bc\x1b[?7l\x1b[2J\x1b[0;1mSeaBIOS\rTea",
+		"TeaBIOS\n",
+	},
+	{
+		// New origin and absolute positioning.
+		"Line 1\n\x1bcWine B\nFine 3\x1b[1;6H2\x1b[HL\nL",
+		"Line 1\nLine 2\nLine 3\n",
+	},
+	{
+		// In-line positioning (without corner cases).
+		"A\x1b[CB\x1b[2C?\x1b[DC\x1b[2D\b->",
+		"A B->C\n",
+	},
+	{
+		// Up and down.
+		"\nB\x1bMA\v\vC" + "\x1b[4EG" + "\x1b[FF" + "\x1b[2FD" + "\x1b[EE",
+		" A\nB\nC\nD\nE\nF\nG\n",
+	},
+	{
+		// In-line erasing.
+		"1234\b\b\x1b[K\n5678\b\b\x1b[0K\n" + "abcd\b\b\x1b[1K\nefgh\x1b[2K",
+		"12\n56\n  cd\n\n",
+	},
+}
+
+func TestTerminal(t *testing.T) {
+	for _, test := range tests {
+		tw := terminalWriter{}
+		if _, err := tw.Write([]byte(test.push)); err != nil {
+			t.Errorf("%#v: %s", test.push, err)
+			continue
+		}
+		have := string(tw.Serialize(0))
+		if have != test.want {
+			t.Errorf("%#v: %#v; want %#v", test.push, have, test.want)
+		}
+	}
+}
+
+func TestTerminalExploded(t *testing.T) {
+Loop:
+	for _, test := range tests {
+		tw := terminalWriter{}
+		for _, b := range []byte(test.push) {
+			if _, err := tw.Write([]byte{b}); err != nil {
+				t.Errorf("%#v: %s", test.push, err)
+				continue Loop
+			}
+		}
+		have := string(tw.Serialize(0))
+		if have != test.want {
+			t.Errorf("%#v: %#v; want %#v", test.push, have, test.want)
+		}
+	}
+}
+
+func TestTerminalUpdateGroups(t *testing.T) {
+	tw := terminalWriter{}
+	collect := func() (have []int) {
+		for _, line := range tw.lines {
+			have = append(have, line.updateGroup)
+		}
+		return
+	}
+
+	// 0: A      0 0 0
+	// 1: B X    1 1 1
+	// 2: C Y 1  2 1 1
+	// 3:   Z 2    3 2
+	// 4:     3      4
+	tw.Write([]byte("A\nB\nC\x1b[FX\nY\nZ"))
+	have, want := collect(), []int{0, 1, 1, 3}
+	if !slices.Equal(want, have) {
+		t.Errorf("update groups: %+v; want: %+v", have, want)
+	}
+
+	tw.Write([]byte("\x1b[F1\n2\n3"))
+	have, want = collect(), []int{0, 1, 1, 2, 4}
+	if !slices.Equal(want, have) {
+		t.Errorf("update groups: %+v; want: %+v", have, want)
+	}
+}