4. Unit Tests

4. Unit Tests

In this section, we use googletest as the tool of unit test. The installation source is from this website: https://github.com/google/googletest. The function of googletest is to use assertions to check whether the output value of a programme is corresponded to the expected value. If does not correspond, the system will report a failure. There are two kinds of assertions, namely ASSERT and EXPECT. The former can produce a serious failure if detects an error in the programme, then stop the running of the programme. The latter can generate a slight failure and do not stop the program even if a mistake detected.

The commands in googletest are as follow: ASSERT_TRUE(condition_1), or EXPECT_TURE(condition_1): judge whether condition_1 is true. ASSERT_EQ(value_1,value_2), or EXPECT_EQ(value_1,value_2): judge whether value_1 equals to value_2. ASSERT_NE(value_1,value_2), or EXPECT_NE(value_1,value_2): judge whether value_1 inequals to value_2. ASSERT_LT(value_1,value_2), or EXPECT_LT(value_1,value_2): judge whether value_1 less than value_2. ASSERT_LE(value_1,value_2), or EXPECT_LE(value_1,value_2): judge whether value_1 less than or equal to value_2. ASSERT_GT(value_1,value_2), or EXPECT_GT(value_1,value_2): judge whether value_1 greater than value_2. ASSERT_GE(value_1,value_2), or EXPECT_GE(value_1,value_2): judge whether value_1 greater than or equal to value_2.

To try the viability of this test, we defined two functions, one calculates the absolute value of a number, another figures out the cube of a number.the codes are as follow:

#include #include "gtest/gtest.h" int cube(int a) {return aaa;} int abs(int x) {return x>0 ? x : -x;}

Then we typed several googletest commands as follow:

TEST(TestCube, JudgeTrueOrFalse) { EXPECT_EQ(cube(2),8); ASSERT_NE(100,cube(5)); ASSERT_LT(300,cube(8)); EXPECT_LE(125,cube(5)); ASSERT_GE(1000,cube(10)); }

TEST(TestAbs,JudgeTrueOrFalse) { ASSERT_TRUE(abs(2)==2); ASSERT_TRUE(abs(-5)==5); ASSERT_FALSE(abs(-3)==-3); EXPECT_EQ(abs(-3),abs(3)); EXPECT_NE(abs(0),1); ASSERT_GT(abs(-5),0); ASSERT_LT(abs(4),6); ASSERT_LE(-2,abs(-3)); ASSERT_GE(abs(-1),0); } int main() { ::testing::InitGoogleTest(); return RUN_ALL_TESTS(); }

In this case, there is no failure, the result is shown as follow: [==========] Running 2 tests from 2 test suites. [----------] Global test environment set-up. [----------] 1 test from TestCube [ RUN ] TestCube.JudgeTrueOrFalse [ OK ] TestCube.JudgeTrueOrFalse (0 ms) [----------] 1 test from TestCube (2 ms total)

[----------] 1 test from TestAbs [ RUN ] TestAbs.JudgeTrueOrFalse [ OK ] TestAbs.JudgeTrueOrFalse (0 ms) [----------] 1 test from TestAbs (2 ms total)

[----------] Global test environment tear-down [==========] 2 tests from 2 test suites ran. (12 ms total) [ PASSED ] 2 tests.

Process finished with exit code 0

To test the serious failure of the command ASSERT*, we changed all the commands in the test for the cube function into mistake, and all of them use ASSERT*, but remain all the commands in the test for absolute value correct:

TEST(TestCube, JudgeTrueOrFalse) { ASSERT_EQ(cube(2),7); ASSERT_NE(125,cube(5)); ASSERT_LT(600,cube(8)); ASSERT_LE(126,cube(5)); ASSERT_GE(998,cube(10)); }

After running, the results reveal as follow: [==========] Running 2 tests from 2 test suites. [----------] Global test environment set-up. [----------] 1 test from TestCube [ RUN ] TestCube.JudgeTrueOrFalse D:/study in Britain/Mechatronics/googletest/try_google_test_1/main.cpp:9: Failure Expected equality of these values: cube(2) Which is: 8 7 [ FAILED ] TestCube.JudgeTrueOrFalse (3 ms) [----------] 1 test from TestCube (5 ms total)

[----------] 1 test from TestAbs [ RUN ] TestAbs.JudgeTrueOrFalse [ OK ] TestAbs.JudgeTrueOrFalse (0 ms) [----------] 1 test from TestAbs (1 ms total)

[----------] Global test environment tear-down [==========] 2 tests from 2 test suites ran. (13 ms total) [ PASSED ] 1 test. [ FAILED ] 1 test, listed below: [ FAILED ] TestCube.JudgeTrueOrFalse

1 FAILED TEST

Process finished with exit code 1

Obviously, there should be five failures in the test for cube, but the system only reports one failure, namely ASSERT_EQ(cube(2),7). This means it stops the test for this function after detecting one failure. However, the test for absolute value remains "OK", which means the failure in testing one function does not affect another function's test.