Function TestUnsafePutVarUint32PhysicalWriteWidth

go/fory/buffer_test.go:89–114

TestUnsafePutVarUint32PhysicalWriteWidth verifies that UnsafePutVarUint32 performs an 8-byte physical write for 5-byte varints and that Reserve(8) (as required by the contract) keeps those 8 bytes within the backing array.

(t *testing.T)

// an 8-byte physical write for 5-byte varints and that Reserve(8) (as required by
// the contract) keeps those 8 bytes within the backing array.
func TestUnsafePutVarUint32PhysicalWriteWidth(t *testing.T) {
	const sentinelByte = byte(0xAB)
	const totalCap = 16
	backing := make([]byte, totalCap, totalCap)

	// Fill [8, totalCap) with sentinels; [0, 8) is the reserved window.
	for i := 8; i < totalCap; i++ {
		backing[i] = sentinelByte
	}

	// Expose 8 bytes of len, matching Reserve(8) contract.
	buf := NewByteBuffer(backing[:8])

	// Reserve(8) should return immediately as len(data) is already 8.
	buf.Reserve(8)

	// Encode value >= 2^28 (5 varint bytes) which triggers 8-byte bulk write.
	written := buf.UnsafePutVarUint32(0, 1<<28)
	require.Equal(t, 5, written, "expected 5 logical bytes written")

	// Verify bytes [8, totalCap) remain untouched by the 8-byte bulk write.
	for i := 8; i < totalCap; i++ {
		require.Equal(t, sentinelByte, backing[i],
			"byte at index %d is outside the 8-byte reserved window and must not be written", i)
	}
}

func TestReadVarUint32RejectsOverflowFifthByte(t *testing.T) {
	for _, data := range [][]byte{