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30 // This sample shows how to test code relying on some global flag variables.
31 // Combine() helps with generating all possible combinations of such flags,
32 // and each test is given one combination as a parameter.
34 // Use class definitions to test from this header.
35 #include "prime_tables.h"
36 #include "gtest/gtest.h"
39 // Suppose we want to introduce a new, improved implementation of PrimeTable
40 // which combines speed of PrecalcPrimeTable and versatility of
41 // OnTheFlyPrimeTable (see prime_tables.h). Inside it instantiates both
42 // PrecalcPrimeTable and OnTheFlyPrimeTable and uses the one that is more
43 // appropriate under the circumstances. But in low memory conditions, it can be
44 // told to instantiate without PrecalcPrimeTable instance at all and use only
45 // OnTheFlyPrimeTable.
46 class HybridPrimeTable : public PrimeTable {
48 HybridPrimeTable(bool force_on_the_fly, int max_precalculated)
49 : on_the_fly_impl_(new OnTheFlyPrimeTable),
50 precalc_impl_(force_on_the_fly
52 : new PreCalculatedPrimeTable(max_precalculated)),
53 max_precalculated_(max_precalculated) {}
54 ~HybridPrimeTable() override {
55 delete on_the_fly_impl_;
59 bool IsPrime(int n) const override {
60 if (precalc_impl_ != nullptr && n < max_precalculated_)
61 return precalc_impl_->IsPrime(n);
63 return on_the_fly_impl_->IsPrime(n);
66 int GetNextPrime(int p) const override {
68 if (precalc_impl_ != nullptr && p < max_precalculated_)
69 next_prime = precalc_impl_->GetNextPrime(p);
71 return next_prime != -1 ? next_prime : on_the_fly_impl_->GetNextPrime(p);
75 OnTheFlyPrimeTable* on_the_fly_impl_;
76 PreCalculatedPrimeTable* precalc_impl_;
77 int max_precalculated_;
80 using ::testing::Bool;
81 using ::testing::Combine;
82 using ::testing::TestWithParam;
83 using ::testing::Values;
85 // To test all code paths for HybridPrimeTable we must test it with numbers
86 // both within and outside PreCalculatedPrimeTable's capacity and also with
87 // PreCalculatedPrimeTable disabled. We do this by defining fixture which will
88 // accept different combinations of parameters for instantiating a
89 // HybridPrimeTable instance.
90 class PrimeTableTest : public TestWithParam< ::std::tuple<bool, int> > {
92 void SetUp() override {
93 bool force_on_the_fly;
94 int max_precalculated;
95 std::tie(force_on_the_fly, max_precalculated) = GetParam();
96 table_ = new HybridPrimeTable(force_on_the_fly, max_precalculated);
98 void TearDown() override {
102 HybridPrimeTable* table_;
105 TEST_P(PrimeTableTest, ReturnsFalseForNonPrimes) {
106 // Inside the test body, you can refer to the test parameter by GetParam().
107 // In this case, the test parameter is a PrimeTable interface pointer which
108 // we can use directly.
109 // Please note that you can also save it in the fixture's SetUp() method
110 // or constructor and use saved copy in the tests.
112 EXPECT_FALSE(table_->IsPrime(-5));
113 EXPECT_FALSE(table_->IsPrime(0));
114 EXPECT_FALSE(table_->IsPrime(1));
115 EXPECT_FALSE(table_->IsPrime(4));
116 EXPECT_FALSE(table_->IsPrime(6));
117 EXPECT_FALSE(table_->IsPrime(100));
120 TEST_P(PrimeTableTest, ReturnsTrueForPrimes) {
121 EXPECT_TRUE(table_->IsPrime(2));
122 EXPECT_TRUE(table_->IsPrime(3));
123 EXPECT_TRUE(table_->IsPrime(5));
124 EXPECT_TRUE(table_->IsPrime(7));
125 EXPECT_TRUE(table_->IsPrime(11));
126 EXPECT_TRUE(table_->IsPrime(131));
129 TEST_P(PrimeTableTest, CanGetNextPrime) {
130 EXPECT_EQ(2, table_->GetNextPrime(0));
131 EXPECT_EQ(3, table_->GetNextPrime(2));
132 EXPECT_EQ(5, table_->GetNextPrime(3));
133 EXPECT_EQ(7, table_->GetNextPrime(5));
134 EXPECT_EQ(11, table_->GetNextPrime(7));
135 EXPECT_EQ(131, table_->GetNextPrime(128));
138 // In order to run value-parameterized tests, you need to instantiate them,
139 // or bind them to a list of values which will be used as test parameters.
140 // You can instantiate them in a different translation module, or even
141 // instantiate them several times.
143 // Here, we instantiate our tests with a list of parameters. We must combine
144 // all variations of the boolean flag suppressing PrecalcPrimeTable and some
145 // meaningful values for tests. We choose a small value (1), and a value that
146 // will put some of the tested numbers beyond the capability of the
147 // PrecalcPrimeTable instance and some inside it (10). Combine will produce all
148 // possible combinations.
149 INSTANTIATE_TEST_SUITE_P(MeaningfulTestParameters, PrimeTableTest,
150 Combine(Bool(), Values(1, 10)));