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// Copyright 2015 The Chromium 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 "cast/streaming/expanded_value_base.h"
#include "gtest/gtest.h"
namespace openscreen {
namespace cast {
namespace {
// A basic subclass of ExpandedValueBase to use for testing.
class TestValue : public ExpandedValueBase<int64_t, TestValue> {
public:
explicit TestValue(int64_t value) : ExpandedValueBase(value) {}
};
} // namespace
// Tests the various scenarios of truncating and then re-expanding values, and
// confirming the correct behavior. Note that, while the code below just tests
// truncation/expansion to/from 8 bits, the 16- and 32-bit cases are implicitly
// confirmed because the Expand() method uses the compiler to derive all of its
// constants (based on the type of its argument).
TEST(ExpandedValueBaseTest, TruncationAndExpansion) {
// Test that expansion works when the reference is always equal to the value
// that was truncated.
for (int64_t i = -512; i <= 512; ++i) {
const TestValue original_value(i);
const uint8_t truncated = original_value.lower_8_bits();
const TestValue reference(i);
ASSERT_EQ(original_value, reference.Expand(truncated)) << "i=" << i;
}
// Test that expansion works when the reference is always one less than the
// value that was truncated.
for (int64_t i = -512; i <= 512; ++i) {
const TestValue original_value(i);
const uint8_t truncated = original_value.lower_8_bits();
const TestValue reference(i - 1);
ASSERT_EQ(original_value, reference.Expand(truncated)) << "i=" << i;
}
// Test that expansion works when the reference is always one greater than the
// value that was truncated.
for (int64_t i = -512; i <= 512; ++i) {
const TestValue original_value(i);
const uint8_t truncated = original_value.lower_8_bits();
const TestValue reference(i + 1);
ASSERT_EQ(original_value, reference.Expand(truncated)) << "i=" << i;
}
// Test cases where the difference between the original value and the fixed
// reference is within the range [-128,+127]. The truncated value should
// always be re-expanded to the original value.
for (int64_t bias = -5; bias <= 5; ++bias) {
for (int64_t i = -128; i <= 127; ++i) {
const TestValue original_value(bias + i);
const uint8_t truncated = original_value.lower_8_bits();
const TestValue reference(bias);
ASSERT_EQ(original_value, reference.Expand(truncated))
<< "bias=" << bias << ", i=" << i;
}
}
// Test cases where the difference between the original value and the fixed
// reference is within the range [+128,+255]. When the truncated value is
// re-expanded, it should be 256 less than the original value.
for (int64_t bias = -5; bias <= 5; ++bias) {
for (int64_t i = 128; i <= 255; ++i) {
// Example: Let |original_value| be 192. Then, the truncated 8-bit value
// will be 0xc0. When a |reference| of zero is asked to expand 0xc0 back
// to the original value, it should produce -64 since -64 is closer to
// |reference| than 192.
const TestValue original_value(bias + i);
const uint8_t truncated = original_value.lower_8_bits();
const TestValue reexpanded_value(bias + i - 256);
ASSERT_EQ(reexpanded_value.lower_8_bits(), truncated);
const TestValue reference(bias);
ASSERT_EQ(reexpanded_value, reference.Expand(truncated))
<< "bias=" << bias << ", i=" << i;
}
}
// Test cases where the difference between the original value and the fixed
// reference is within the range [-256,-129]. When the truncated value is
// re-expanded, it should be 256 more than the original value.
for (int64_t bias = -5; bias <= 5; ++bias) {
for (int64_t i = -256; i <= -129; ++i) {
// Example: Let |original_value| be -192. Then, the truncated 8-bit value
// will be 0x40. When a |reference| of zero is asked to expand 0x40 back
// to the original value, it should produce 64 since 64 is closer to the
// |reference| than -192.
const TestValue original_value(bias + i);
const uint8_t truncated = original_value.lower_8_bits();
const TestValue reexpanded_value(bias + i + 256);
ASSERT_EQ(reexpanded_value.lower_8_bits(), truncated);
const TestValue reference(bias);
ASSERT_EQ(reexpanded_value, reference.Expand(truncated))
<< "bias=" << bias << ", i=" << i;
}
}
}
} // namespace cast
} // namespace openscreen
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