// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <assert.h>
#include <stdio.h>

#include <hid-parser/item.h>
#include <hid-parser/parser.h>
#include <hid-parser/report.h>
#include <hid-parser/units.h>
#include <hid-parser/usages.h>

#include <unistd.h>
#include <unittest/unittest.h>

// See hid-utest-data.cpp for the definitions of the test data
extern "C" const uint8_t push_pop_test[62];
extern "C" const uint8_t minmax_signed_test[68];

// Tests that the max values of the MinMax are parsed as unsigned
// data when the min values are >= 0. Also tests that the max values
// are parsed as signed data when the min values are < 0.
bool parse_minmax_signed() {
    BEGIN_TEST;

    hid::DeviceDescriptor* dev = nullptr;
    auto res = hid::ParseReportDescriptor(minmax_signed_test, sizeof(minmax_signed_test), &dev);
    ASSERT_EQ(res, hid::ParseResult::kParseOk);

    const auto fields = dev->report[0].input_fields;

    EXPECT_EQ(fields[0].attr.logc_mm.min, 0);
    EXPECT_EQ(fields[0].attr.logc_mm.max, 0xFF);
    EXPECT_EQ(fields[0].attr.phys_mm.min, 0);
    EXPECT_EQ(fields[0].attr.phys_mm.max, 0xFFFF);

    EXPECT_EQ(fields[1].attr.logc_mm.min, -5);
    EXPECT_EQ(fields[1].attr.logc_mm.max, -1);
    EXPECT_EQ(fields[1].attr.phys_mm.min, -5);
    EXPECT_EQ(fields[1].attr.phys_mm.max, -1);

    END_TEST;
}

// Test that the push and pop operations complete successfully.
// Pushing saves all of the GLOBAL items.
// Popping restores the previously saved GLOBAL items
bool parse_push_pop() {
    BEGIN_TEST;
    hid::DeviceDescriptor* dev = nullptr;
    auto res = hid::ParseReportDescriptor(push_pop_test, sizeof(push_pop_test), &dev);
    ASSERT_EQ(res, hid::ParseResult::kParseOk);

    // A single report with id zero, this means no report id.
    ASSERT_EQ(dev->rep_count, 1u);
    EXPECT_EQ(dev->report[0].report_id, 0);

    // The only report has 12 fields.
    EXPECT_EQ(dev->report[0].input_count, 12);
    const auto fields = dev->report[0].input_fields;

    // All fields are input type with report id = 0.
    for (uint8_t ix = 0; ix != dev->report[0].input_count; ++ix) {
        EXPECT_EQ(fields[ix].report_id, 0);
        EXPECT_EQ(fields[ix].type, hid::kInput);
    }

    // First 3 fields are the buttons, with usages 1, 2, 3, in the button page.
    auto expected_flags = hid::kData | hid::kAbsolute | hid::kScalar;

    for (uint8_t ix = 0; ix != 3; ++ix) {
        EXPECT_EQ(fields[ix].attr.usage.page, hid::usage::Page::kButton);
        EXPECT_EQ(fields[ix].attr.usage.usage, uint32_t(ix + 1));
        EXPECT_EQ(fields[ix].attr.bit_sz, 1);
        EXPECT_EQ(fields[ix].attr.logc_mm.min, 0);
        EXPECT_EQ(fields[ix].attr.logc_mm.max, 1);
        EXPECT_EQ(expected_flags & fields[ix].flags, expected_flags);
    }

    // Next field is 5 bits constant. Aka padding.
    EXPECT_EQ(fields[3].attr.bit_sz, 5);
    EXPECT_EQ(hid::kConstant & fields[3].flags, hid::kConstant);

    // Next comes 'X' field, 8 bits data, relative.
    expected_flags = hid::kData | hid::kRelative | hid::kScalar;

    EXPECT_EQ(fields[4].attr.usage.page, hid::usage::Page::kGenericDesktop);
    EXPECT_EQ(fields[4].attr.usage.usage, hid::usage::GenericDesktop::kX);
    EXPECT_EQ(fields[4].attr.bit_sz, 8);
    EXPECT_EQ(fields[4].attr.logc_mm.min, -127);
    EXPECT_EQ(fields[4].attr.logc_mm.max, 127);
    EXPECT_EQ(fields[4].attr.phys_mm.min, 0);
    EXPECT_EQ(fields[4].attr.phys_mm.max, 0);
    EXPECT_EQ(expected_flags & fields[4].flags, expected_flags);

    // Next comes 'Y' field, same as 'X'.
    EXPECT_EQ(fields[5].attr.usage.page, hid::usage::Page::kGenericDesktop);
    EXPECT_EQ(fields[5].attr.usage.usage, hid::usage::GenericDesktop::kY);
    EXPECT_EQ(fields[5].attr.bit_sz, 8);
    EXPECT_EQ(fields[5].attr.logc_mm.min, -127);
    EXPECT_EQ(fields[5].attr.logc_mm.max, 127);
    EXPECT_EQ(fields[5].attr.phys_mm.min, 0);
    EXPECT_EQ(fields[5].attr.phys_mm.max, 0);
    EXPECT_EQ(expected_flags & fields[4].flags, expected_flags);

    // Next comes 'X' and 'Y' field again
    expected_flags = hid::kData | hid::kRelative | hid::kScalar;
    EXPECT_EQ(fields[6].attr.usage.page, hid::usage::Page::kGenericDesktop);
    EXPECT_EQ(fields[6].attr.usage.usage, 0);
    EXPECT_EQ(fields[6].attr.bit_sz, 8);
    EXPECT_EQ(fields[6].attr.logc_mm.min, -127);
    EXPECT_EQ(fields[6].attr.logc_mm.max, 127);
    EXPECT_EQ(fields[6].attr.phys_mm.min, 0);
    EXPECT_EQ(fields[6].attr.phys_mm.max, 0);
    EXPECT_EQ(expected_flags & fields[6].flags, expected_flags);
    EXPECT_EQ(fields[7].attr.usage.page, hid::usage::Page::kGenericDesktop);
    EXPECT_EQ(fields[7].attr.usage.usage, 0);
    EXPECT_EQ(fields[7].attr.bit_sz, 8);
    EXPECT_EQ(fields[7].attr.logc_mm.min, -127);
    EXPECT_EQ(fields[7].attr.logc_mm.max, 127);
    EXPECT_EQ(fields[7].attr.phys_mm.min, 0);
    EXPECT_EQ(fields[7].attr.phys_mm.max, 0);
    EXPECT_EQ(expected_flags & fields[7].flags, expected_flags);

    // Next is the popped padding field
    EXPECT_EQ(fields[8].attr.bit_sz, 5);
    EXPECT_EQ(hid::kConstant & fields[8].flags, hid::kConstant);

    // Last 3 fields are the popped buttons
    expected_flags = hid::kData | hid::kAbsolute | hid::kScalar;

    for (uint8_t ix = 9; ix != 12; ++ix) {
        EXPECT_EQ(fields[ix].attr.usage.page, hid::usage::Page::kButton);
        EXPECT_EQ(fields[ix].attr.usage.usage, 0);
        EXPECT_EQ(fields[ix].attr.bit_sz, 1);
        EXPECT_EQ(fields[ix].attr.logc_mm.min, 0);
        EXPECT_EQ(fields[ix].attr.logc_mm.max, 1);
        EXPECT_EQ(expected_flags & fields[ix].flags, expected_flags);
    }

    END_TEST;
}

bool usage_helper() {
    BEGIN_TEST;
    auto usage = hid::USAGE(hid::usage::Page::kDigitizer, hid::usage::Digitizer::kContactID);
    EXPECT_EQ(usage.page, static_cast<uint16_t>(hid::usage::Page::kDigitizer));
    EXPECT_EQ(usage.usage, static_cast<uint32_t>(hid::usage::Digitizer::kContactID));
    END_TEST;
}

bool minmax_operators() {
    BEGIN_TEST;
    EXPECT_TRUE((hid::MinMax{-1, 1} == hid::MinMax{-1, 1}));
    EXPECT_FALSE((hid::MinMax{0, 1} == hid::MinMax{-1, 1}));
    EXPECT_FALSE((hid::MinMax{-1, 1} == hid::MinMax{0, 1}));
    EXPECT_FALSE((hid::MinMax{-1, 2} == hid::MinMax{-1, 1}));
    EXPECT_FALSE((hid::MinMax{-1, 1} == hid::MinMax{-1, 2}));
    EXPECT_FALSE((hid::MinMax{0, 2} == hid::MinMax{-1, 1}));
    END_TEST;
}

bool usage_operators() {
    BEGIN_TEST;
    EXPECT_TRUE(
        hid::USAGE(hid::usage::Page::kDigitizer, hid::usage::Digitizer::kContactID) ==
        hid::USAGE(hid::usage::Page::kDigitizer, hid::usage::Digitizer::kContactID));
    EXPECT_FALSE(
        hid::USAGE(hid::usage::Page::kDigitizer, hid::usage::Digitizer::kTipSwitch) ==
        hid::USAGE(hid::usage::Page::kDigitizer, hid::usage::Digitizer::kContactID));
    EXPECT_FALSE(
        hid::USAGE(hid::usage::Page::kGenericDesktop, hid::usage::GenericDesktop::kX) ==
        hid::USAGE(hid::usage::Page::kDigitizer, hid::usage::Digitizer::kContactID));
    END_TEST;
}

bool extract_tests() {
    BEGIN_TEST;
    uint8_t report[] = {0x0F, 0x0F, 0x0F, 0x0F, 0x0F};
    size_t report_len = sizeof(report);
    hid::Attributes attr;
    bool ret;

    uint8_t int8;
    attr.offset = 0;
    attr.bit_sz = 8;
    ret = ExtractUint(report, report_len, attr, &int8);
    EXPECT_TRUE(ret);
    EXPECT_EQ(int8, 0x0F);

    attr.offset = 2;
    attr.bit_sz = 6;
    ret = ExtractUint(report, report_len, attr, &int8);
    EXPECT_TRUE(ret);
    EXPECT_EQ(int8, 0x03);

    attr.offset = 3;
    attr.bit_sz = 2;
    ret = ExtractUint(report, report_len, attr, &int8);
    EXPECT_TRUE(ret);
    EXPECT_EQ(int8, 0x01);

    // Test over a byte boundary
    attr.offset = 4;
    attr.bit_sz = 8;
    ret = ExtractUint(report, report_len, attr, &int8);
    EXPECT_TRUE(ret);
    EXPECT_EQ(int8, 0xF0);

    uint16_t int16;
    attr.offset = 0;
    attr.bit_sz = 16;
    ret = ExtractUint(report, report_len, attr, &int16);
    EXPECT_TRUE(ret);
    EXPECT_EQ(int16, 0x0F0F);

    attr.offset = 4;
    attr.bit_sz = 16;
    ret = ExtractUint(report, report_len, attr, &int16);
    EXPECT_TRUE(ret);
    EXPECT_EQ(int16, 0xF0F0);

    uint32_t int32;
    attr.offset = 0;
    attr.bit_sz = 32;
    ret = ExtractUint(report, report_len, attr, &int32);
    EXPECT_TRUE(ret);
    EXPECT_EQ(int32, 0x0F0F0F0F);

    attr.offset = 4;
    attr.bit_sz = 32;
    ret = ExtractUint(report, report_len, attr, &int32);
    EXPECT_TRUE(ret);
    EXPECT_EQ(int32, 0xF0F0F0F0);

    // Test that it fails if the attr is too large
    attr.offset = 0;
    attr.bit_sz = 9;
    ret = ExtractUint(report, report_len, attr, &int8);
    EXPECT_FALSE(ret);

    // Test that it fails if it goes past the end of the report
    attr.offset = 36;
    attr.bit_sz = 16;
    ret = ExtractUint(report, report_len, attr, &int16);
    EXPECT_FALSE(ret);

    END_TEST;
}

bool extract_as_unit_tests() {
    BEGIN_TEST;

    uint8_t report[] = {0x0F, 10, 0x0F, 0x0F, 0x0F};
    size_t report_len = sizeof(report);
    hid::Attributes attr = {};
    bool ret;
    double val_out;

    // Test a signed conversion with the same logc / physical max
    attr.offset = 0;
    attr.bit_sz = 8;

    attr.logc_mm.max = 100;
    attr.logc_mm.min = -100;
    attr.phys_mm.max = 100;
    attr.phys_mm.min = -100;

    ret = ExtractAsUnit(report, report_len, attr, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), 0x0F);

    // Test that a signed conversion actually sign extends
    attr.offset = 0;
    attr.bit_sz = 4;

    attr.logc_mm.max = 10;
    attr.logc_mm.min = -10;
    attr.phys_mm.max = 10;
    attr.phys_mm.min = -10;

    ret = ExtractAsUnit(report, report_len, attr, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), -1);

    // Test an unsigned conversion
    attr.offset = 0;
    attr.bit_sz = 4;

    attr.logc_mm.max = 100;
    attr.logc_mm.min = 0;
    attr.phys_mm.max = 100;
    attr.phys_mm.min = 0;

    ret = ExtractAsUnit(report, report_len, attr, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<uint32_t>(val_out), 0xF);

    // Test a signed conversion with a negative number that x3 the number
    attr.offset = 0;
    attr.bit_sz = 4;

    attr.logc_mm.max = 10;
    attr.logc_mm.min = -10;
    attr.phys_mm.max = 30;
    attr.phys_mm.min = -30;

    ret = ExtractAsUnit(report, report_len, attr, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), -3);

    // Test an unsigned conversion with a negative number that x2.5 the number
    attr.offset = 8;
    attr.bit_sz = 8;

    attr.logc_mm.max = 10;
    attr.logc_mm.min = 0;
    attr.phys_mm.max = 25;
    attr.phys_mm.min = 0;

    ret = ExtractAsUnit(report, report_len, attr, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), 25);

    // Test that when phys max and min are 0, there is no scaling
    attr.offset = 8;
    attr.bit_sz = 8;

    attr.logc_mm.max = 100;
    attr.logc_mm.min = 0;
    attr.phys_mm.max = 0;
    attr.phys_mm.min = 0;

    ret = ExtractAsUnit(report, report_len, attr, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), 10);

    // Test ExtractWithUnit
    attr.offset = 8;
    attr.bit_sz = 8;

    attr.logc_mm.max = 10;
    attr.logc_mm.min = 0;
    attr.phys_mm.max = 25;
    attr.phys_mm.min = 0;

    // 25 * 10^0 cm = 250 * 10^-1 cm
    hid::Unit unit_in;
    unit_in.type = 0;
    hid::unit::SetSystem(unit_in, hid::unit::System::si_linear);
    hid::unit::SetLengthExp(unit_in, 1);
    unit_in.exp = 0;

    hid::Unit unit_out;
    unit_out.type = 0;
    hid::unit::SetSystem(unit_out, hid::unit::System::si_linear);
    hid::unit::SetLengthExp(unit_out, 1);
    unit_out.exp = -1;

    attr.unit = unit_in;

    ret = ExtractWithUnit(report, report_len, attr, unit_out, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), 250);

    END_TEST;
}

bool unit_tests() {
    BEGIN_TEST;
    hid::Unit unit_in;
    hid::Unit unit_out;
    bool ret;
    double val_out;

    // Test the unit type setting/getting.
    {
        unit_in.type = 0;
        hid::unit::SetSystem(unit_in, hid::unit::System::si_linear);
        hid::unit::SetLengthExp(unit_in, 2);
        hid::unit::SetMassExp(unit_in, 3);
        hid::unit::SetTimeExp(unit_in, 7);
        hid::unit::SetTemperatureExp(unit_in, -1);
        hid::unit::SetCurrentExp(unit_in, -2);
        hid::unit::SetLuminousExp(unit_in, -8);

        auto sys = hid::unit::GetSystem(unit_in);
        EXPECT_EQ(sys, hid::unit::System::si_linear);

        int exp = hid::unit::GetLengthExp(unit_in);
        EXPECT_EQ(exp, 2);
        exp = hid::unit::GetMassExp(unit_in);
        EXPECT_EQ(exp, 3);
        exp = hid::unit::GetTimeExp(unit_in);
        EXPECT_EQ(exp, 7);
        exp = hid::unit::GetTemperatureExp(unit_in);
        EXPECT_EQ(exp, -1);
        exp = hid::unit::GetCurrentExp(unit_in);
        EXPECT_EQ(exp, -2);
        exp = hid::unit::GetLuminousExp(unit_in);
        EXPECT_EQ(exp, -8);
    }

    // Test same units convert to lower exponent.
    // 1 * 10^0 cm = 100 * 10^-1 cm
    unit_in.type = 0;
    hid::unit::SetSystem(unit_in, hid::unit::System::si_linear);
    hid::unit::SetLengthExp(unit_in, 1);
    unit_in.exp = 0;

    unit_out.type = 0;
    hid::unit::SetSystem(unit_out, hid::unit::System::si_linear);
    hid::unit::SetLengthExp(unit_out, 1);
    unit_out.exp = -2;

    ret = hid::unit::ConvertUnits(unit_in, 1, unit_out, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), 100);

    // Test same units convert to higher exponent.
    // 100 * 10^0 cm = 1 * 10^2 cm
    unit_in.type = 0;
    hid::unit::SetSystem(unit_in, hid::unit::System::si_linear);
    hid::unit::SetLengthExp(unit_in, 1);
    unit_in.exp = 0;

    unit_out.type = 0;
    hid::unit::SetSystem(unit_out, hid::unit::System::si_linear);
    hid::unit::SetLengthExp(unit_out, 1);
    unit_out.exp = 2;

    ret = hid::unit::ConvertUnits(unit_in, 100, unit_out, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), 1);

    // Distance Conversion Tests.

    // 100 * 10^1 inches == 25 * 10^2 cm
    unit_in.type = 0;
    hid::unit::SetSystem(unit_in, hid::unit::System::eng_linear);
    hid::unit::SetLengthExp(unit_in, 1);
    unit_in.exp = 1;

    unit_out.type = 0;
    hid::unit::SetSystem(unit_out, hid::unit::System::si_linear);
    hid::unit::SetLengthExp(unit_out, 1);
    unit_out.exp = 2;

    ret = hid::unit::ConvertUnits(unit_in, 100, unit_out, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), 25);

    // 1 * 10^2 cm == 39 * 10^0 in
    unit_in.type = 0;
    hid::unit::SetSystem(unit_in, hid::unit::System::si_linear);
    hid::unit::SetLengthExp(unit_in, 1);
    unit_in.exp = 2;

    unit_out.type = 0;
    hid::unit::SetSystem(unit_out, hid::unit::System::eng_linear);
    hid::unit::SetLengthExp(unit_out, 1);
    unit_out.exp = 0;

    ret = hid::unit::ConvertUnits(unit_in, 1, unit_out, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), 39);

    // 100 * 10^0 cm^3 == 6 * 10^0 in^3
    unit_in.type = 0;
    hid::unit::SetSystem(unit_in, hid::unit::System::si_linear);
    hid::unit::SetLengthExp(unit_in, 3);
    unit_in.exp = 0;

    unit_out.type = 0;
    hid::unit::SetSystem(unit_out, hid::unit::System::eng_linear);
    hid::unit::SetLengthExp(unit_out, 3);
    unit_out.exp = 0;

    ret = hid::unit::ConvertUnits(unit_in, 100, unit_out, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), 6);

    // 1 * 10^0 in^3 == 16 * 10^0 cm^3
    unit_in.type = 0;
    hid::unit::SetSystem(unit_in, hid::unit::System::eng_linear);
    hid::unit::SetLengthExp(unit_in, 3);
    unit_in.exp = 0;

    unit_out.type = 0;
    hid::unit::SetSystem(unit_out, hid::unit::System::si_linear);
    hid::unit::SetLengthExp(unit_out, 3);
    unit_out.exp = 0;

    ret = hid::unit::ConvertUnits(unit_in, 1, unit_out, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), 16);

    // 180 degrees = 3 radians
    unit_in.type = 0;
    hid::unit::SetSystem(unit_in, hid::unit::System::eng_rotation);
    hid::unit::SetLengthExp(unit_in, 1);
    unit_in.exp = 0;

    unit_out.type = 0;
    hid::unit::SetSystem(unit_out, hid::unit::System::si_rotation);
    hid::unit::SetLengthExp(unit_out, 1);
    unit_out.exp = 0;

    ret = hid::unit::ConvertUnits(unit_in, 180, unit_out, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), 3);

    // 3 radians = 171 degrees
    unit_in.type = 0;
    hid::unit::SetSystem(unit_in, hid::unit::System::si_rotation);
    hid::unit::SetLengthExp(unit_in, 1);
    unit_in.exp = 0;

    unit_out.type = 0;
    hid::unit::SetSystem(unit_out, hid::unit::System::eng_rotation);
    hid::unit::SetLengthExp(unit_out, 1);
    unit_out.exp = 0;

    ret = hid::unit::ConvertUnits(unit_in, 3, unit_out, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), 171);

    // Mass Converson Tests.
    // 1 slug = 14593 grams
    unit_in.type = 0;
    hid::unit::SetSystem(unit_in, hid::unit::System::eng_linear);
    hid::unit::SetMassExp(unit_in, 1);
    unit_in.exp = 0;

    unit_out.type = 0;
    hid::unit::SetSystem(unit_out, hid::unit::System::si_linear);
    hid::unit::SetMassExp(unit_out, 1);
    unit_out.exp = 0;

    ret = hid::unit::ConvertUnits(unit_in, 1, unit_out, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), 14593);

    // 200000 grams = 13 slugs
    unit_in.type = 0;
    hid::unit::SetSystem(unit_in, hid::unit::System::si_linear);
    hid::unit::SetMassExp(unit_in, 1);
    unit_in.exp = 0;

    unit_out.type = 0;
    hid::unit::SetSystem(unit_out, hid::unit::System::eng_linear);
    hid::unit::SetMassExp(unit_out, 1);
    unit_out.exp = 0;

    ret = hid::unit::ConvertUnits(unit_in, 200000, unit_out, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), 13);

    // Temperature Conversion Tests.
    // 32 F = 273 K
    unit_in.type = 0;
    hid::unit::SetSystem(unit_in, hid::unit::System::eng_linear);
    hid::unit::SetTemperatureExp(unit_in, 1);
    unit_in.exp = 0;

    unit_out.type = 0;
    hid::unit::SetSystem(unit_out, hid::unit::System::si_linear);
    hid::unit::SetTemperatureExp(unit_out, 1);
    unit_out.exp = 0;

    ret = hid::unit::ConvertUnits(unit_in, 32, unit_out, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), 273);

    // 273 K = 31 F
    unit_in.type = 0;
    hid::unit::SetSystem(unit_in, hid::unit::System::si_linear);
    hid::unit::SetTemperatureExp(unit_in, 1);
    unit_in.exp = 0;

    unit_out.type = 0;
    hid::unit::SetSystem(unit_out, hid::unit::System::eng_linear);
    hid::unit::SetTemperatureExp(unit_out, 1);
    unit_out.exp = 0;

    ret = hid::unit::ConvertUnits(unit_in, 273, unit_out, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), 31);

    // Misc Tests.
    // SlugUnits to Newtons (Force conversion).
    // 100 * 10^0 slug * in / seconds^2 == 37 * 10^5 g * cm / seconds^2
    unit_in.type = 0;
    hid::unit::SetSystem(unit_in, hid::unit::System::eng_linear);
    hid::unit::SetMassExp(unit_in, 1);
    hid::unit::SetLengthExp(unit_in, 1);
    hid::unit::SetTimeExp(unit_in, -2);
    unit_in.exp = 0;

    unit_out.type = 0;
    hid::unit::SetSystem(unit_out, hid::unit::System::si_linear);
    hid::unit::SetMassExp(unit_out, 1);
    hid::unit::SetLengthExp(unit_out, 1);
    hid::unit::SetTimeExp(unit_out, -2);
    unit_out.exp = 5;

    ret = hid::unit::ConvertUnits(unit_in, 100, unit_out, &val_out);
    EXPECT_TRUE(ret);
    EXPECT_EQ(static_cast<int32_t>(val_out), 37);

    // Failure Tests.
    // Can't convert between different units.
    unit_in.type = 0;
    hid::unit::SetSystem(unit_in, hid::unit::System::eng_linear);
    hid::unit::SetMassExp(unit_in, 1);
    unit_in.exp = 0;

    unit_out.type = 0;
    hid::unit::SetSystem(unit_out, hid::unit::System::si_linear);
    hid::unit::SetMassExp(unit_out, 2);
    unit_out.exp = 0;

    ret = hid::unit::ConvertUnits(unit_in, 1, unit_out, &val_out);
    EXPECT_FALSE(ret);

    // Can't convert between rotation and linear distance.
    unit_in.type = 0;
    hid::unit::SetSystem(unit_in, hid::unit::System::eng_rotation);
    hid::unit::SetLengthExp(unit_in, 1);
    unit_in.exp = 0;

    unit_out.type = 0;
    hid::unit::SetSystem(unit_out, hid::unit::System::si_linear);
    hid::unit::SetLengthExp(unit_out, 1);
    unit_out.exp = 0;

    ret = hid::unit::ConvertUnits(unit_in, 1, unit_out, &val_out);
    EXPECT_FALSE(ret);

    END_TEST;
}

BEGIN_TEST_CASE(hidparser_helper_tests)
RUN_TEST(parse_minmax_signed)
RUN_TEST(parse_push_pop)
RUN_TEST(usage_helper)
RUN_TEST(minmax_operators)
RUN_TEST(usage_operators)
RUN_TEST(extract_tests)
RUN_TEST(extract_as_unit_tests)
RUN_TEST(unit_tests)
END_TEST_CASE(hidparser_helper_tests)