1 files changed, 85 insertions, 0 deletions
diff --git a/hotline/decode_test.go b/hotline/decode_test.go
new file mode 100644
index 0000000..663f7ce
--- /dev/null
+++ b/hotline/decode_test.go
@@ -0,0 +1,85 @@
+package hotline
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestClientIDFromBytes(t *testing.T) {
+	tests := []struct {
+		name   string
+		b      []byte
+		want   ClientID
+		wantOk bool
+	}{
+		{name: "valid 2 bytes", b: []byte{0x00, 0x05}, want: ClientID{0x00, 0x05}, wantOk: true},
+		{name: "nil", b: nil, wantOk: false},
+		{name: "too short", b: []byte{0x01}, wantOk: false},
+		{name: "too long", b: []byte{0x01, 0x02, 0x03}, wantOk: false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, ok := ClientIDFromBytes(tt.b)
+			assert.Equal(t, tt.wantOk, ok)
+			if tt.wantOk {
+				assert.Equal(t, tt.want, got)
+			}
+		})
+	}
+}
+
+func TestChatIDFromBytes(t *testing.T) {
+	tests := []struct {
+		name   string
+		b      []byte
+		want   ChatID
+		wantOk bool
+	}{
+		{name: "valid 4 bytes", b: []byte{0x00, 0x00, 0x00, 0x09}, want: ChatID{0x00, 0x00, 0x00, 0x09}, wantOk: true},
+		{name: "nil", b: nil, wantOk: false},
+		{name: "too short", b: []byte{0x01, 0x02, 0x03}, wantOk: false},
+		{name: "too long", b: []byte{0x01, 0x02, 0x03, 0x04, 0x05}, wantOk: false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, ok := ChatIDFromBytes(tt.b)
+			assert.Equal(t, tt.wantOk, ok)
+			if tt.wantOk {
+				assert.Equal(t, tt.want, got)
+			}
+		})
+	}
+}
+
+func TestFileResumeData_UnmarshalBinary(t *testing.T) {
+	// A well-formed buffer: 42-byte header with ForkCount=1, plus one 16-byte fork.
+	valid := make([]byte, resumeDataHeaderLen+forkInfoLen)
+	valid[41] = 1 // ForkCount low byte
+
+	t.Run("valid single-fork buffer parses", func(t *testing.T) {
+		var frd FileResumeData
+		require.NoError(t, frd.UnmarshalBinary(valid))
+		assert.Len(t, frd.ForkInfoList, 1)
+	})
+
+	t.Run("buffer shorter than header returns error, no panic", func(t *testing.T) {
+		var frd FileResumeData
+		assert.Error(t, frd.UnmarshalBinary(make([]byte, 10)))
+	})
+
+	t.Run("fork count overrunning the buffer returns error, no panic", func(t *testing.T) {
+		b := make([]byte, resumeDataHeaderLen) // header only, no fork bytes
+		b[41] = 3                              // claims 3 forks that aren't present
+		var frd FileResumeData
+		assert.Error(t, frd.UnmarshalBinary(b))
+	})
+
+	t.Run("zero fork count yields an empty list", func(t *testing.T) {
+		b := make([]byte, resumeDataHeaderLen)
+		var frd FileResumeData
+		require.NoError(t, frd.UnmarshalBinary(b))
+		assert.Empty(t, frd.ForkInfoList)
+	})
+}