1 // Copyright 2008 Google Inc.
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3 //
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7 //
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29 //
30 // Author: vladl@google.com (Vlad Losev)
31
32 // This sample shows how to test code relying on some global flag variables.
33 // Combine() helps with generating all possible combinations of such flags,
34 // and each test is given one combination as a parameter.
35
36 // Use class definitions to test from this header.
37 #include "prime_tables.h"
38
39 #include <gtest/gtest.h>
40
41 #if GTEST_HAS_COMBINE
42
43 // Suppose we want to introduce a new, improved implementation of PrimeTable
44 // which combines speed of PrecalcPrimeTable and versatility of
45 // OnTheFlyPrimeTable (see prime_tables.h). Inside it instantiates both
46 // PrecalcPrimeTable and OnTheFlyPrimeTable and uses the one that is more
47 // appropriate under the circumstances. But in low memory conditions, it can be
48 // told to instantiate without PrecalcPrimeTable instance at all and use only
49 // OnTheFlyPrimeTable.
50 class HybridPrimeTable : public PrimeTable {
51 public:
HybridPrimeTable(bool force_on_the_fly,int max_precalculated)52 HybridPrimeTable(bool force_on_the_fly, int max_precalculated)
53 : on_the_fly_impl_(new OnTheFlyPrimeTable),
54 precalc_impl_(force_on_the_fly ? NULL :
55 new PreCalculatedPrimeTable(max_precalculated)),
56 max_precalculated_(max_precalculated) {}
~HybridPrimeTable()57 virtual ~HybridPrimeTable() {
58 delete on_the_fly_impl_;
59 delete precalc_impl_;
60 }
61
IsPrime(int n) const62 virtual bool IsPrime(int n) const {
63 if (precalc_impl_ != NULL && n < max_precalculated_)
64 return precalc_impl_->IsPrime(n);
65 else
66 return on_the_fly_impl_->IsPrime(n);
67 }
68
GetNextPrime(int p) const69 virtual int GetNextPrime(int p) const {
70 int next_prime = -1;
71 if (precalc_impl_ != NULL && p < max_precalculated_)
72 next_prime = precalc_impl_->GetNextPrime(p);
73
74 return next_prime != -1 ? next_prime : on_the_fly_impl_->GetNextPrime(p);
75 }
76
77 private:
78 OnTheFlyPrimeTable* on_the_fly_impl_;
79 PreCalculatedPrimeTable* precalc_impl_;
80 int max_precalculated_;
81 };
82
83 using ::testing::TestWithParam;
84 using ::testing::Bool;
85 using ::testing::Values;
86 using ::testing::Combine;
87
88 // To test all code paths for HybridPrimeTable we must test it with numbers
89 // both within and outside PreCalculatedPrimeTable's capacity and also with
90 // PreCalculatedPrimeTable disabled. We do this by defining fixture which will
91 // accept different combinations of parameters for instantiating a
92 // HybridPrimeTable instance.
93 class PrimeTableTest : public TestWithParam< ::std::tr1::tuple<bool, int> > {
94 protected:
SetUp()95 virtual void SetUp() {
96 // This can be written as
97 //
98 // bool force_on_the_fly;
99 // int max_precalculated;
100 // tie(force_on_the_fly, max_precalculated) = GetParam();
101 //
102 // once the Google C++ Style Guide allows use of ::std::tr1::tie.
103 //
104 bool force_on_the_fly = ::std::tr1::get<0>(GetParam());
105 int max_precalculated = ::std::tr1::get<1>(GetParam());
106 table_ = new HybridPrimeTable(force_on_the_fly, max_precalculated);
107 }
TearDown()108 virtual void TearDown() {
109 delete table_;
110 table_ = NULL;
111 }
112 HybridPrimeTable* table_;
113 };
114
TEST_P(PrimeTableTest,ReturnsFalseForNonPrimes)115 TEST_P(PrimeTableTest, ReturnsFalseForNonPrimes) {
116 // Inside the test body, you can refer to the test parameter by GetParam().
117 // In this case, the test parameter is a PrimeTable interface pointer which
118 // we can use directly.
119 // Please note that you can also save it in the fixture's SetUp() method
120 // or constructor and use saved copy in the tests.
121
122 EXPECT_FALSE(table_->IsPrime(-5));
123 EXPECT_FALSE(table_->IsPrime(0));
124 EXPECT_FALSE(table_->IsPrime(1));
125 EXPECT_FALSE(table_->IsPrime(4));
126 EXPECT_FALSE(table_->IsPrime(6));
127 EXPECT_FALSE(table_->IsPrime(100));
128 }
129
TEST_P(PrimeTableTest,ReturnsTrueForPrimes)130 TEST_P(PrimeTableTest, ReturnsTrueForPrimes) {
131 EXPECT_TRUE(table_->IsPrime(2));
132 EXPECT_TRUE(table_->IsPrime(3));
133 EXPECT_TRUE(table_->IsPrime(5));
134 EXPECT_TRUE(table_->IsPrime(7));
135 EXPECT_TRUE(table_->IsPrime(11));
136 EXPECT_TRUE(table_->IsPrime(131));
137 }
138
TEST_P(PrimeTableTest,CanGetNextPrime)139 TEST_P(PrimeTableTest, CanGetNextPrime) {
140 EXPECT_EQ(2, table_->GetNextPrime(0));
141 EXPECT_EQ(3, table_->GetNextPrime(2));
142 EXPECT_EQ(5, table_->GetNextPrime(3));
143 EXPECT_EQ(7, table_->GetNextPrime(5));
144 EXPECT_EQ(11, table_->GetNextPrime(7));
145 EXPECT_EQ(131, table_->GetNextPrime(128));
146 }
147
148 // In order to run value-parameterized tests, you need to instantiate them,
149 // or bind them to a list of values which will be used as test parameters.
150 // You can instantiate them in a different translation module, or even
151 // instantiate them several times.
152 //
153 // Here, we instantiate our tests with a list of parameters. We must combine
154 // all variations of the boolean flag suppressing PrecalcPrimeTable and some
155 // meaningful values for tests. We choose a small value (1), and a value that
156 // will put some of the tested numbers beyond the capability of the
157 // PrecalcPrimeTable instance and some inside it (10). Combine will produce all
158 // possible combinations.
159 INSTANTIATE_TEST_CASE_P(MeaningfulTestParameters,
160 PrimeTableTest,
161 Combine(Bool(), Values(1, 10)));
162
163 #else
164
165 // Google Test may not support Combine() with some compilers. If we
166 // use conditional compilation to compile out all code referring to
167 // the gtest_main library, MSVC linker will not link that library at
168 // all and consequently complain about missing entry point defined in
169 // that library (fatal error LNK1561: entry point must be
170 // defined). This dummy test keeps gtest_main linked in.
TEST(DummyTest,CombineIsNotSupportedOnThisPlatform)171 TEST(DummyTest, CombineIsNotSupportedOnThisPlatform) {}
172
173 #endif // GTEST_HAS_COMBINE
174