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29 //
30 // Author: wan@google.com (Zhanyong Wan)
31
32 // This sample shows how to test common properties of multiple
33 // implementations of the same interface (aka interface tests).
34
35 // The interface and its implementations are in this header.
36 #include "prime_tables.h"
37
38 #include <gtest/gtest.h>
39
40 // First, we define some factory functions for creating instances of
41 // the implementations. You may be able to skip this step if all your
42 // implementations can be constructed the same way.
43
44 template <class T>
45 PrimeTable* CreatePrimeTable();
46
47 template <>
CreatePrimeTable()48 PrimeTable* CreatePrimeTable<OnTheFlyPrimeTable>() {
49 return new OnTheFlyPrimeTable;
50 }
51
52 template <>
CreatePrimeTable()53 PrimeTable* CreatePrimeTable<PreCalculatedPrimeTable>() {
54 return new PreCalculatedPrimeTable(10000);
55 }
56
57 // Then we define a test fixture class template.
58 template <class T>
59 class PrimeTableTest : public testing::Test {
60 protected:
61 // The ctor calls the factory function to create a prime table
62 // implemented by T.
PrimeTableTest()63 PrimeTableTest() : table_(CreatePrimeTable<T>()) {}
64
~PrimeTableTest()65 virtual ~PrimeTableTest() { delete table_; }
66
67 // Note that we test an implementation via the base interface
68 // instead of the actual implementation class. This is important
69 // for keeping the tests close to the real world scenario, where the
70 // implementation is invoked via the base interface. It avoids
71 // got-yas where the implementation class has a method that shadows
72 // a method with the same name (but slightly different argument
73 // types) in the base interface, for example.
74 PrimeTable* const table_;
75 };
76
77 #if GTEST_HAS_TYPED_TEST
78
79 using testing::Types;
80
81 // Google Test offers two ways for reusing tests for different types.
82 // The first is called "typed tests". You should use it if you
83 // already know *all* the types you are gonna exercise when you write
84 // the tests.
85
86 // To write a typed test case, first use
87 //
88 // TYPED_TEST_CASE(TestCaseName, TypeList);
89 //
90 // to declare it and specify the type parameters. As with TEST_F,
91 // TestCaseName must match the test fixture name.
92
93 // The list of types we want to test.
94 typedef Types<OnTheFlyPrimeTable, PreCalculatedPrimeTable> Implementations;
95
96 TYPED_TEST_CASE(PrimeTableTest, Implementations);
97
98 // Then use TYPED_TEST(TestCaseName, TestName) to define a typed test,
99 // similar to TEST_F.
TYPED_TEST(PrimeTableTest,ReturnsFalseForNonPrimes)100 TYPED_TEST(PrimeTableTest, ReturnsFalseForNonPrimes) {
101 // Inside the test body, you can refer to the type parameter by
102 // TypeParam, and refer to the fixture class by TestFixture. We
103 // don't need them in this example.
104
105 // Since we are in the template world, C++ requires explicitly
106 // writing 'this->' when referring to members of the fixture class.
107 // This is something you have to learn to live with.
108 EXPECT_FALSE(this->table_->IsPrime(-5));
109 EXPECT_FALSE(this->table_->IsPrime(0));
110 EXPECT_FALSE(this->table_->IsPrime(1));
111 EXPECT_FALSE(this->table_->IsPrime(4));
112 EXPECT_FALSE(this->table_->IsPrime(6));
113 EXPECT_FALSE(this->table_->IsPrime(100));
114 }
115
TYPED_TEST(PrimeTableTest,ReturnsTrueForPrimes)116 TYPED_TEST(PrimeTableTest, ReturnsTrueForPrimes) {
117 EXPECT_TRUE(this->table_->IsPrime(2));
118 EXPECT_TRUE(this->table_->IsPrime(3));
119 EXPECT_TRUE(this->table_->IsPrime(5));
120 EXPECT_TRUE(this->table_->IsPrime(7));
121 EXPECT_TRUE(this->table_->IsPrime(11));
122 EXPECT_TRUE(this->table_->IsPrime(131));
123 }
124
TYPED_TEST(PrimeTableTest,CanGetNextPrime)125 TYPED_TEST(PrimeTableTest, CanGetNextPrime) {
126 EXPECT_EQ(2, this->table_->GetNextPrime(0));
127 EXPECT_EQ(3, this->table_->GetNextPrime(2));
128 EXPECT_EQ(5, this->table_->GetNextPrime(3));
129 EXPECT_EQ(7, this->table_->GetNextPrime(5));
130 EXPECT_EQ(11, this->table_->GetNextPrime(7));
131 EXPECT_EQ(131, this->table_->GetNextPrime(128));
132 }
133
134 // That's it! Google Test will repeat each TYPED_TEST for each type
135 // in the type list specified in TYPED_TEST_CASE. Sit back and be
136 // happy that you don't have to define them multiple times.
137
138 #endif // GTEST_HAS_TYPED_TEST
139
140 #if GTEST_HAS_TYPED_TEST_P
141
142 using testing::Types;
143
144 // Sometimes, however, you don't yet know all the types that you want
145 // to test when you write the tests. For example, if you are the
146 // author of an interface and expect other people to implement it, you
147 // might want to write a set of tests to make sure each implementation
148 // conforms to some basic requirements, but you don't know what
149 // implementations will be written in the future.
150 //
151 // How can you write the tests without committing to the type
152 // parameters? That's what "type-parameterized tests" can do for you.
153 // It is a bit more involved than typed tests, but in return you get a
154 // test pattern that can be reused in many contexts, which is a big
155 // win. Here's how you do it:
156
157 // First, define a test fixture class template. Here we just reuse
158 // the PrimeTableTest fixture defined earlier:
159
160 template <class T>
161 class PrimeTableTest2 : public PrimeTableTest<T> {
162 };
163
164 // Then, declare the test case. The argument is the name of the test
165 // fixture, and also the name of the test case (as usual). The _P
166 // suffix is for "parameterized" or "pattern".
167 TYPED_TEST_CASE_P(PrimeTableTest2);
168
169 // Next, use TYPED_TEST_P(TestCaseName, TestName) to define a test,
170 // similar to what you do with TEST_F.
TYPED_TEST_P(PrimeTableTest2,ReturnsFalseForNonPrimes)171 TYPED_TEST_P(PrimeTableTest2, ReturnsFalseForNonPrimes) {
172 EXPECT_FALSE(this->table_->IsPrime(-5));
173 EXPECT_FALSE(this->table_->IsPrime(0));
174 EXPECT_FALSE(this->table_->IsPrime(1));
175 EXPECT_FALSE(this->table_->IsPrime(4));
176 EXPECT_FALSE(this->table_->IsPrime(6));
177 EXPECT_FALSE(this->table_->IsPrime(100));
178 }
179
TYPED_TEST_P(PrimeTableTest2,ReturnsTrueForPrimes)180 TYPED_TEST_P(PrimeTableTest2, ReturnsTrueForPrimes) {
181 EXPECT_TRUE(this->table_->IsPrime(2));
182 EXPECT_TRUE(this->table_->IsPrime(3));
183 EXPECT_TRUE(this->table_->IsPrime(5));
184 EXPECT_TRUE(this->table_->IsPrime(7));
185 EXPECT_TRUE(this->table_->IsPrime(11));
186 EXPECT_TRUE(this->table_->IsPrime(131));
187 }
188
TYPED_TEST_P(PrimeTableTest2,CanGetNextPrime)189 TYPED_TEST_P(PrimeTableTest2, CanGetNextPrime) {
190 EXPECT_EQ(2, this->table_->GetNextPrime(0));
191 EXPECT_EQ(3, this->table_->GetNextPrime(2));
192 EXPECT_EQ(5, this->table_->GetNextPrime(3));
193 EXPECT_EQ(7, this->table_->GetNextPrime(5));
194 EXPECT_EQ(11, this->table_->GetNextPrime(7));
195 EXPECT_EQ(131, this->table_->GetNextPrime(128));
196 }
197
198 // Type-parameterized tests involve one extra step: you have to
199 // enumerate the tests you defined:
200 REGISTER_TYPED_TEST_CASE_P(
201 PrimeTableTest2, // The first argument is the test case name.
202 // The rest of the arguments are the test names.
203 ReturnsFalseForNonPrimes, ReturnsTrueForPrimes, CanGetNextPrime);
204
205 // At this point the test pattern is done. However, you don't have
206 // any real test yet as you haven't said which types you want to run
207 // the tests with.
208
209 // To turn the abstract test pattern into real tests, you instantiate
210 // it with a list of types. Usually the test pattern will be defined
211 // in a .h file, and anyone can #include and instantiate it. You can
212 // even instantiate it more than once in the same program. To tell
213 // different instances apart, you give each of them a name, which will
214 // become part of the test case name and can be used in test filters.
215
216 // The list of types we want to test. Note that it doesn't have to be
217 // defined at the time we write the TYPED_TEST_P()s.
218 typedef Types<OnTheFlyPrimeTable, PreCalculatedPrimeTable>
219 PrimeTableImplementations;
220 INSTANTIATE_TYPED_TEST_CASE_P(OnTheFlyAndPreCalculated, // Instance name
221 PrimeTableTest2, // Test case name
222 PrimeTableImplementations); // Type list
223
224 #endif // GTEST_HAS_TYPED_TEST_P
225