1 // Copyright 2015 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "cast/streaming/expanded_value_base.h"
6
7 #include "gtest/gtest.h"
8
9 namespace openscreen {
10 namespace cast {
11
12 namespace {
13
14 // A basic subclass of ExpandedValueBase to use for testing.
15 class TestValue : public ExpandedValueBase<int64_t, TestValue> {
16 public:
TestValue(int64_t value)17 explicit TestValue(int64_t value) : ExpandedValueBase(value) {}
18 };
19
20 } // namespace
21
22 // Tests the various scenarios of truncating and then re-expanding values, and
23 // confirming the correct behavior. Note that, while the code below just tests
24 // truncation/expansion to/from 8 bits, the 16- and 32-bit cases are implicitly
25 // confirmed because the Expand() method uses the compiler to derive all of its
26 // constants (based on the type of its argument).
TEST(ExpandedValueBaseTest,TruncationAndExpansion)27 TEST(ExpandedValueBaseTest, TruncationAndExpansion) {
28 // Test that expansion works when the reference is always equal to the value
29 // that was truncated.
30 for (int64_t i = -512; i <= 512; ++i) {
31 const TestValue original_value(i);
32 const uint8_t truncated = original_value.lower_8_bits();
33 const TestValue reference(i);
34 ASSERT_EQ(original_value, reference.Expand(truncated)) << "i=" << i;
35 }
36
37 // Test that expansion works when the reference is always one less than the
38 // value that was truncated.
39 for (int64_t i = -512; i <= 512; ++i) {
40 const TestValue original_value(i);
41 const uint8_t truncated = original_value.lower_8_bits();
42 const TestValue reference(i - 1);
43 ASSERT_EQ(original_value, reference.Expand(truncated)) << "i=" << i;
44 }
45
46 // Test that expansion works when the reference is always one greater than the
47 // value that was truncated.
48 for (int64_t i = -512; i <= 512; ++i) {
49 const TestValue original_value(i);
50 const uint8_t truncated = original_value.lower_8_bits();
51 const TestValue reference(i + 1);
52 ASSERT_EQ(original_value, reference.Expand(truncated)) << "i=" << i;
53 }
54
55 // Test cases where the difference between the original value and the fixed
56 // reference is within the range [-128,+127]. The truncated value should
57 // always be re-expanded to the original value.
58 for (int64_t bias = -5; bias <= 5; ++bias) {
59 for (int64_t i = -128; i <= 127; ++i) {
60 const TestValue original_value(bias + i);
61 const uint8_t truncated = original_value.lower_8_bits();
62 const TestValue reference(bias);
63 ASSERT_EQ(original_value, reference.Expand(truncated))
64 << "bias=" << bias << ", i=" << i;
65 }
66 }
67
68 // Test cases where the difference between the original value and the fixed
69 // reference is within the range [+128,+255]. When the truncated value is
70 // re-expanded, it should be 256 less than the original value.
71 for (int64_t bias = -5; bias <= 5; ++bias) {
72 for (int64_t i = 128; i <= 255; ++i) {
73 // Example: Let |original_value| be 192. Then, the truncated 8-bit value
74 // will be 0xc0. When a |reference| of zero is asked to expand 0xc0 back
75 // to the original value, it should produce -64 since -64 is closer to
76 // |reference| than 192.
77 const TestValue original_value(bias + i);
78 const uint8_t truncated = original_value.lower_8_bits();
79 const TestValue reexpanded_value(bias + i - 256);
80 ASSERT_EQ(reexpanded_value.lower_8_bits(), truncated);
81 const TestValue reference(bias);
82 ASSERT_EQ(reexpanded_value, reference.Expand(truncated))
83 << "bias=" << bias << ", i=" << i;
84 }
85 }
86
87 // Test cases where the difference between the original value and the fixed
88 // reference is within the range [-256,-129]. When the truncated value is
89 // re-expanded, it should be 256 more than the original value.
90 for (int64_t bias = -5; bias <= 5; ++bias) {
91 for (int64_t i = -256; i <= -129; ++i) {
92 // Example: Let |original_value| be -192. Then, the truncated 8-bit value
93 // will be 0x40. When a |reference| of zero is asked to expand 0x40 back
94 // to the original value, it should produce 64 since 64 is closer to the
95 // |reference| than -192.
96 const TestValue original_value(bias + i);
97 const uint8_t truncated = original_value.lower_8_bits();
98 const TestValue reexpanded_value(bias + i + 256);
99 ASSERT_EQ(reexpanded_value.lower_8_bits(), truncated);
100 const TestValue reference(bias);
101 ASSERT_EQ(reexpanded_value, reference.Expand(truncated))
102 << "bias=" << bias << ", i=" << i;
103 }
104 }
105 }
106
107 } // namespace cast
108 } // namespace openscreen
109