feat: While closing OpsLog will keep the same size and position for next launch

internal/steppir/steppir_test.go

@@ -0,0 +1,84 @@
+package steppir
+
+import (
+	"encoding/binary"
+	"testing"
+)
+
+// The exact bytes are the correctness checksum. If buildSet ever drifts from the
+// three-source-agreed layout, this fails — a wrong packet is a silently mistuned
+// antenna, far worse than a compile error.
+func TestBuildSetLayout(t *testing.T) {
+	// 14.074 MHz, normal, set-freq. freq/10 = 1_407_400 = 0x00 0x15 0x79 0xA8.
+	pkt := buildSet(14_074_000, DirNormal, '1')
+	want := []byte{'@', 'A', 0x00, 0x15, 0x79, 0xA8, 0x00, 0x00, '1', 0x00, 0x0D}
+	if len(pkt) != 11 {
+		t.Fatalf("packet is %d bytes, want 11", len(pkt))
+	}
+	for i := range want {
+		if pkt[i] != want[i] {
+			t.Fatalf("byte %d = 0x%02X, want 0x%02X\n got %X\nwant %X", i, pkt[i], want[i], pkt, want)
+		}
+	}
+	// Frequency must round-trip: bytes [2:6] × 10 = Hz.
+	if got := int(binary.BigEndian.Uint32(pkt[2:6])) * 10; got != 14_074_000 {
+		t.Fatalf("freq round-trip = %d, want 14074000", got)
+	}
+}
+
+func TestBuildSetDirectionAndCommand(t *testing.T) {
+	cases := []struct {
+		dir     int
+		cmd     byte
+		wantDir byte
+		wantCmd byte
+	}{
+		{DirNormal, '1', 0x00, '1'},
+		{Dir180, '1', 0x40, '1'},
+		{DirBi, '1', 0x80, '1'},
+		{DirNormal, 'S', 0x00, 'S'}, // retract / home
+		{DirNormal, 'R', 0x00, 'R'}, // autotrack on
+	}
+	for _, c := range cases {
+		pkt := buildSet(21_000_000, c.dir, c.cmd)
+		if pkt[7] != c.wantDir {
+			t.Errorf("dir %d → byte 0x%02X, want 0x%02X", c.dir, pkt[7], c.wantDir)
+		}
+		if pkt[8] != c.wantCmd {
+			t.Errorf("cmd %q → byte 0x%02X, want 0x%02X", c.cmd, pkt[8], c.wantCmd)
+		}
+	}
+}
+
+// parseStatus decodes what the controller sends back — the inverse of buildSet's
+// frequency field, plus the direction nibble.
+func TestParseStatus(t *testing.T) {
+	frame := []byte{0x00, 0x00, 0x00, 0x15, 0x79, 0xA8, 0x01, 0x40, '1', '2', 0x0D}
+	st, err := parseStatus(frame)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if st.Frequency != 14074 {
+		t.Errorf("freq = %d kHz, want 14074", st.Frequency)
+	}
+	if st.Direction != Dir180 {
+		t.Errorf("direction = %d, want %d (180°)", st.Direction, Dir180)
+	}
+	if st.MotorsMoving != 0 { // 0x01 is the always-set bit, not motion
+		t.Errorf("moving = %d, want 0 (only the always-on bit set)", st.MotorsMoving)
+	}
+
+	// Motors busy: a bit beyond 0x01 is set.
+	frame[6] = 0x07
+	st, _ = parseStatus(frame)
+	if st.MotorsMoving == 0 {
+		t.Error("active-motors 0x07 should read as moving")
+	}
+
+	// 0xFF is "command received", not motion.
+	frame[6] = 0xFF
+	st, _ = parseStatus(frame)
+	if st.MotorsMoving != 0 {
+		t.Error("active-motors 0xFF (command received) must not read as moving")
+	}
+}