diff --git a/test/message/payload.cpp b/test/message/payload.cpp
new file mode 100644
index 0000000..9d20ff0
--- /dev/null
+++ b/test/message/payload.cpp
@@ -0,0 +1,308 @@
+/**
+ * Copyright © 2018 Intel Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <ipmid/api.hpp>
+#include <ipmid/message.hpp>
+
+#include <gtest/gtest.h>
+
+TEST(Payload, InputSize)
+{
+    std::vector<uint8_t> i = {0xbf, 0x04, 0x86, 0x00, 0x02};
+    size_t input_size = i.size();
+    ipmi::message::Payload p(std::forward<std::vector<uint8_t>>(i));
+    ASSERT_EQ(input_size, p.size());
+}
+
+TEST(Payload, OutputSize)
+{
+    ipmi::message::Payload p;
+    ASSERT_EQ(0, p.size());
+    std::vector<uint8_t> i = {0xbf, 0x04, 0x86, 0x00, 0x02};
+    p.pack(i);
+    ASSERT_EQ(i.size(), p.size());
+    p.pack(i);
+    p.pack(i);
+    ASSERT_EQ(3 * i.size(), p.size());
+}
+
+TEST(Payload, Resize)
+{
+    std::vector<uint8_t> i = {0xbf, 0x04, 0x86, 0x00, 0x02};
+    ipmi::message::Payload p;
+    p.pack(i);
+    p.resize(16);
+    ASSERT_EQ(p.size(), 16);
+}
+
+TEST(Payload, Data)
+{
+    std::vector<uint8_t> i = {0xbf, 0x04, 0x86, 0x00, 0x02};
+    ipmi::message::Payload p;
+    p.pack(i);
+    ASSERT_NE(nullptr, p.data());
+}
+
+TEST(PayloadResponse, Append)
+{
+    std::string s("0123456789abcdef");
+    ipmi::message::Payload p;
+    p.append(s.data(), s.data() + s.size());
+    ASSERT_EQ(s.size(), p.size());
+}
+
+TEST(PayloadResponse, AppendDrain)
+{
+    std::string s("0123456789abcdef");
+    ipmi::message::Payload p;
+    bool b = true;
+    // first pack a lone bit
+    p.pack(b);
+    p.append(s.data(), s.data() + s.size());
+    // append will 'drain' first, padding the lone bit into a full byte
+    ASSERT_EQ(s.size() + 1, p.size());
+}
+
+TEST(PayloadResponse, AppendBits)
+{
+    ipmi::message::Payload p;
+    p.appendBits(3, 0b101);
+    ASSERT_EQ(p.bitStream, 0b101);
+    p.appendBits(4, 0b1100);
+    ASSERT_EQ(p.bitStream, 0b1100101);
+    p.appendBits(1, 0b1);
+    ASSERT_EQ(p.bitStream, 0);
+    ASSERT_EQ(p.bitCount, 0);
+    // appended 8 bits, should be one byte
+    ASSERT_EQ(p.size(), 1);
+    std::vector<uint8_t> k1 = {0b11100101};
+    ASSERT_EQ(p.raw, k1);
+    p.appendBits(7, 0b1110111);
+    // appended 7 more bits, should still be one byte
+    ASSERT_EQ(p.size(), 1);
+    p.drain();
+    // drain forces padding; should be two bytes now
+    ASSERT_EQ(p.size(), 2);
+    std::vector<uint8_t> k2 = {0b11100101, 0b01110111};
+    ASSERT_EQ(p.raw, k2);
+}
+
+TEST(PayloadResponse, Drain16Bits)
+{
+    ipmi::message::Payload p;
+    p.bitStream = 0b1011010011001111;
+    p.bitCount = 16;
+    p.drain();
+    ASSERT_EQ(p.size(), 2);
+    ASSERT_EQ(p.bitCount, 0);
+    ASSERT_EQ(p.bitStream, 0);
+    std::vector<uint8_t> k1 = {0b11001111, 0b10110100};
+    ASSERT_EQ(p.raw, k1);
+}
+
+TEST(PayloadResponse, Drain15Bits)
+{
+    ipmi::message::Payload p;
+    p.bitStream = 0b101101001100111;
+    p.bitCount = 15;
+    p.drain();
+    ASSERT_EQ(p.size(), 2);
+    ASSERT_EQ(p.bitCount, 0);
+    ASSERT_EQ(p.bitStream, 0);
+    std::vector<uint8_t> k1 = {0b1100111, 0b1011010};
+    ASSERT_EQ(p.raw, k1);
+}
+
+TEST(PayloadResponse, Drain15BitsWholeBytesOnly)
+{
+    ipmi::message::Payload p;
+    p.bitStream = 0b101101001100111;
+    p.bitCount = 15;
+    p.drain(true);
+    // only the first whole byte should have been 'drained' into p.raw
+    ASSERT_EQ(p.size(), 1);
+    ASSERT_EQ(p.bitCount, 7);
+    ASSERT_EQ(p.bitStream, 0b1011010);
+    std::vector<uint8_t> k1 = {0b1100111};
+    ASSERT_EQ(p.raw, k1);
+}
+
+TEST(PayloadRequest, Pop)
+{
+    std::vector<uint8_t> i = {0xbf, 0x04, 0x86, 0x00, 0x02};
+    ipmi::message::Payload p(std::forward<std::vector<uint8_t>>(i));
+    const auto& [vb, ve] = p.pop<uint8_t>(4);
+    std::vector<uint8_t> v(vb, ve);
+    std::vector<uint8_t> k = {0xbf, 0x04, 0x86, 0x00};
+    ASSERT_EQ(v, k);
+}
+
+TEST(PayloadRequest, FillBits)
+{
+    std::vector<uint8_t> i = {0xbf, 0x04, 0x86, 0x00, 0x02};
+    ipmi::message::Payload p(std::forward<std::vector<uint8_t>>(i));
+    p.fillBits(5);
+    ASSERT_FALSE(p.unpackError);
+    ASSERT_EQ(p.bitStream, 0xbf);
+    ASSERT_EQ(p.bitCount, 8);
+    // should still have 5 bits available, no change
+    p.fillBits(5);
+    ASSERT_FALSE(p.unpackError);
+    ASSERT_EQ(p.bitStream, 0xbf);
+    ASSERT_EQ(p.bitCount, 8);
+    // discard 5 bits (low order)
+    p.popBits(5);
+    // should add another byte into the stream (high order)
+    p.fillBits(5);
+    ASSERT_FALSE(p.unpackError);
+    ASSERT_EQ(p.bitStream, 0x25);
+    ASSERT_EQ(p.bitCount, 11);
+}
+
+TEST(PayloadRequest, FillBitsTooManyBits)
+{
+    std::vector<uint8_t> i = {1, 2, 3, 4, 5, 6, 7, 8, 9};
+    ipmi::message::Payload p(std::forward<std::vector<uint8_t>>(i));
+    p.fillBits(72);
+    ASSERT_TRUE(p.unpackError);
+}
+
+TEST(PayloadRequest, FillBitsNotEnoughBytes)
+{
+    std::vector<uint8_t> i = {1, 2, 3, 4};
+    ipmi::message::Payload p(std::forward<std::vector<uint8_t>>(i));
+    p.fillBits(48);
+    ASSERT_TRUE(p.unpackError);
+}
+
+TEST(PayloadRequest, PopBits)
+{
+    std::vector<uint8_t> i = {0xbf, 0x04, 0x86, 0x00, 0x02};
+    ipmi::message::Payload p(std::forward<std::vector<uint8_t>>(i));
+    p.fillBits(4);
+    uint8_t v = p.popBits(4);
+    ASSERT_FALSE(p.unpackError);
+    ASSERT_EQ(p.bitStream, 0x0b);
+    ASSERT_EQ(p.bitCount, 4);
+    ASSERT_EQ(v, 0x0f);
+}
+
+TEST(PayloadRequest, PopBitsNoFillBits)
+{
+    std::vector<uint8_t> i = {0xbf, 0x04, 0x86, 0x00, 0x02};
+    ipmi::message::Payload p(std::forward<std::vector<uint8_t>>(i));
+    p.popBits(4);
+    ASSERT_TRUE(p.unpackError);
+}
+
+TEST(PayloadRequest, DiscardBits)
+{
+    std::vector<uint8_t> i = {0xbf, 0x04, 0x86, 0x00, 0x02};
+    ipmi::message::Payload p(std::forward<std::vector<uint8_t>>(i));
+    p.fillBits(5);
+    ASSERT_FALSE(p.unpackError);
+    ASSERT_EQ(p.bitStream, 0xbf);
+    ASSERT_EQ(p.bitCount, 8);
+    p.discardBits();
+    ASSERT_FALSE(p.unpackError);
+    ASSERT_EQ(p.bitStream, 0);
+    ASSERT_EQ(p.bitCount, 0);
+}
+
+TEST(PayloadRequest, FullyUnpacked)
+{
+    std::vector<uint8_t> i = {0xbf, 0x04, 0x86, 0x00, 0x02};
+    ipmi::message::Payload p(std::forward<std::vector<uint8_t>>(i));
+    uint32_t v1;
+    p.unpack(v1);
+    // still one remaining byte
+    ASSERT_FALSE(p.fullyUnpacked());
+    p.fillBits(3);
+    p.popBits(3);
+    // still five remaining bits
+    ASSERT_FALSE(p.fullyUnpacked());
+    p.fillBits(5);
+    p.popBits(5);
+    // fully unpacked, should be no errors
+    ASSERT_TRUE(p.fullyUnpacked());
+    p.fillBits(4);
+    // fullyUnpacked fails because an attempt to unpack too many bytes
+    ASSERT_FALSE(p.fullyUnpacked());
+}
+
+TEST(PayloadRequest, ResetInternal)
+{
+    std::vector<uint8_t> i = {0xbf, 0x04, 0x86, 0x00, 0x02};
+    ipmi::message::Payload p(std::forward<std::vector<uint8_t>>(i));
+    p.fillBits(4);
+    p.unpackError = true;
+    p.reset();
+    ASSERT_EQ(p.rawIndex, 0);
+    ASSERT_EQ(p.bitStream, 0);
+    ASSERT_EQ(p.bitCount, 0);
+    ASSERT_FALSE(p.unpackError);
+}
+
+TEST(PayloadRequest, ResetUsage)
+{
+    // Payload.reset is used to rewind the unpacking to the initial
+    // state. This is needed so that OEM commands can unpack the group
+    // number or the IANA to determine which handler needs to be called
+    std::vector<uint8_t> i = {0x04, 0x86};
+    ipmi::message::Payload p(std::forward<std::vector<uint8_t>>(i));
+    uint8_t v1;
+    // check that the number of bytes matches
+    ASSERT_EQ(p.unpack(v1), 0);
+    // check that the payload was not fully unpacked
+    ASSERT_FALSE(p.fullyUnpacked());
+    uint8_t k1 = 0x04;
+    // check that the bytes were correctly unpacked (LSB first)
+    ASSERT_EQ(v1, k1);
+    // do a reset on the payload
+    p.reset();
+    // unpack a uint16
+    uint16_t v2;
+    // check that the number of bytes matches
+    ASSERT_EQ(p.unpack(v2), 0);
+    // check that the payload was fully unpacked
+    ASSERT_TRUE(p.fullyUnpacked());
+    uint16_t k2 = 0x8604;
+    // check that the bytes were correctly unpacked (LSB first)
+    ASSERT_EQ(v2, k2);
+}
+
+TEST(PayloadRequest, PartialPayload)
+{
+    std::vector<uint8_t> i = {0xbf, 0x04, 0x86, 0x00, 0x02};
+    ipmi::message::Payload p(std::forward<std::vector<uint8_t>>(i));
+    uint8_t v1;
+    ipmi::message::Payload localPayload;
+    // check that the number of bytes matches
+    ASSERT_EQ(p.unpack(v1, localPayload), 0);
+    // check that the payload was partially unpacked and not in error
+    ASSERT_FALSE(p.fullyUnpacked());
+    ASSERT_FALSE(p.unpackError);
+    // check that the 'extracted' payload is not fully unpacked
+    ASSERT_FALSE(localPayload.fullyUnpacked());
+    uint8_t k1 = 0xbf;
+    // check that the bytes were correctly unpacked (LSB first)
+    ASSERT_EQ(v1, k1);
+    uint32_t v2;
+    // unpack using the 'extracted' payload
+    ASSERT_EQ(localPayload.unpack(v2), 0);
+    ASSERT_TRUE(localPayload.fullyUnpacked());
+    uint32_t k2 = 0x02008604;
+    ASSERT_EQ(v2, k2);
+}