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diff --git a/docs/primer.md b/docs/primer.md index 44a1cb55..4901e1ab 100644 --- a/docs/primer.md +++ b/docs/primer.md @@ -1,84 +1,84 @@ -# Googletest Primer +# GoogleTest Primer -## Introduction: Why googletest? +## Introduction: Why GoogleTest? -*googletest* helps you write better C++ tests. +*GoogleTest* helps you write better C++ tests. -googletest is a testing framework developed by the Testing Technology team with +GoogleTest is a testing framework developed by the Testing Technology team with Google's specific requirements and constraints in mind. Whether you work on -Linux, Windows, or a Mac, if you write C++ code, googletest can help you. And it +Linux, Windows, or a Mac, if you write C++ code, GoogleTest can help you. And it supports *any* kind of tests, not just unit tests. -So what makes a good test, and how does googletest fit in? We believe: +So what makes a good test, and how does GoogleTest fit in? We believe: 1. Tests should be *independent* and *repeatable*. It's a pain to debug a test - that succeeds or fails as a result of other tests. googletest isolates the + that succeeds or fails as a result of other tests. GoogleTest isolates the tests by running each of them on a different object. When a test fails, - googletest allows you to run it in isolation for quick debugging. + GoogleTest allows you to run it in isolation for quick debugging. 2. Tests should be well *organized* and reflect the structure of the tested - code. googletest groups related tests into test suites that can share data + code. GoogleTest groups related tests into test suites that can share data and subroutines. This common pattern is easy to recognize and makes tests easy to maintain. Such consistency is especially helpful when people switch projects and start to work on a new code base. 3. Tests should be *portable* and *reusable*. Google has a lot of code that is - platform-neutral; its tests should also be platform-neutral. googletest + platform-neutral; its tests should also be platform-neutral. GoogleTest works on different OSes, with different compilers, with or without - exceptions, so googletest tests can work with a variety of configurations. + exceptions, so GoogleTest tests can work with a variety of configurations. 4. When tests fail, they should provide as much *information* about the problem - as possible. googletest doesn't stop at the first test failure. Instead, it + as possible. GoogleTest doesn't stop at the first test failure. Instead, it only stops the current test and continues with the next. You can also set up tests that report non-fatal failures after which the current test continues. Thus, you can detect and fix multiple bugs in a single run-edit-compile cycle. 5. The testing framework should liberate test writers from housekeeping chores - and let them focus on the test *content*. googletest automatically keeps + and let them focus on the test *content*. GoogleTest automatically keeps track of all tests defined, and doesn't require the user to enumerate them in order to run them. -6. Tests should be *fast*. With googletest, you can reuse shared resources +6. Tests should be *fast*. With GoogleTest, you can reuse shared resources across tests and pay for the set-up/tear-down only once, without making tests depend on each other. -Since googletest is based on the popular xUnit architecture, you'll feel right +Since GoogleTest is based on the popular xUnit architecture, you'll feel right at home if you've used JUnit or PyUnit before. If not, it will take you about 10 minutes to learn the basics and get started. So let's go! -## Beware of the nomenclature +## Beware of the Nomenclature {: .callout .note} -_Note:_ There might be some confusion arising from different definitions of the -terms _Test_, _Test Case_ and _Test Suite_, so beware of misunderstanding these. +*Note:* There might be some confusion arising from different definitions of the +terms *Test*, *Test Case* and *Test Suite*, so beware of misunderstanding these. -Historically, googletest started to use the term _Test Case_ for grouping +Historically, GoogleTest started to use the term *Test Case* for grouping related tests, whereas current publications, including International Software -Testing Qualifications Board ([ISTQB](http://www.istqb.org/)) materials and +Testing Qualifications Board ([ISTQB](https://www.istqb.org/)) materials and various textbooks on software quality, use the term -_[Test Suite][istqb test suite]_ for this. +*[Test Suite][istqb test suite]* for this. -The related term _Test_, as it is used in googletest, corresponds to the term -_[Test Case][istqb test case]_ of ISTQB and others. +The related term *Test*, as it is used in GoogleTest, corresponds to the term +*[Test Case][istqb test case]* of ISTQB and others. -The term _Test_ is commonly of broad enough sense, including ISTQB's definition -of _Test Case_, so it's not much of a problem here. But the term _Test Case_ as +The term *Test* is commonly of broad enough sense, including ISTQB's definition +of *Test Case*, so it's not much of a problem here. But the term *Test Case* as was used in Google Test is of contradictory sense and thus confusing. -googletest recently started replacing the term _Test Case_ with _Test Suite_. +GoogleTest recently started replacing the term *Test Case* with *Test Suite*. The preferred API is *TestSuite*. The older TestCase API is being slowly deprecated and refactored away. So please be aware of the different definitions of the terms: -Meaning | googletest Term | [ISTQB](http://www.istqb.org/) Term +Meaning | GoogleTest Term | [ISTQB](https://www.istqb.org/) Term :----------------------------------------------------------------------------------- | :---------------------- | :---------------------------------- Exercise a particular program path with specific input values and verify the results | [TEST()](#simple-tests) | [Test Case][istqb test case] -[istqb test case]: http://glossary.istqb.org/en/search/test%20case -[istqb test suite]: http://glossary.istqb.org/en/search/test%20suite +[istqb test case]: https://glossary.istqb.org/en/search/test%20case +[istqb test suite]: https://glossary.istqb.org/en/search/test%20suite ## Basic Concepts -When using googletest, you start by writing *assertions*, which are statements +When using GoogleTest, you start by writing *assertions*, which are statements that check whether a condition is true. An assertion's result can be *success*, *nonfatal failure*, or *fatal failure*. If a fatal failure occurs, it aborts the current function; otherwise the program continues normally. @@ -98,11 +98,11 @@ assertion level and building up to tests and test suites. ## Assertions -googletest assertions are macros that resemble function calls. You test a class +GoogleTest assertions are macros that resemble function calls. You test a class or function by making assertions about its behavior. When an assertion fails, -googletest prints the assertion's source file and line number location, along +GoogleTest prints the assertion's source file and line number location, along with a failure message. You may also supply a custom failure message which will -be appended to googletest's message. +be appended to GoogleTest's message. The assertions come in pairs that test the same thing but have different effects on the current function. `ASSERT_*` versions generate fatal failures when they @@ -118,7 +118,9 @@ Depending on the nature of the leak, it may or may not be worth fixing - so keep this in mind if you get a heap checker error in addition to assertion errors. To provide a custom failure message, simply stream it into the macro using the -`<<` operator or a sequence of such operators. An example: +`<<` operator or a sequence of such operators. See the following example, using +the [`ASSERT_EQ` and `EXPECT_EQ`](reference/assertions.md#EXPECT_EQ) macros to +verify value equality: ```c++ ASSERT_EQ(x.size(), y.size()) << "Vectors x and y are of unequal length"; @@ -133,110 +135,12 @@ macro--in particular, C strings and `string` objects. If a wide string (`wchar_t*`, `TCHAR*` in `UNICODE` mode on Windows, or `std::wstring`) is streamed to an assertion, it will be translated to UTF-8 when printed. -### Basic Assertions - -These assertions do basic true/false condition testing. - -Fatal assertion | Nonfatal assertion | Verifies --------------------------- | -------------------------- | -------------------- -`ASSERT_TRUE(condition);` | `EXPECT_TRUE(condition);` | `condition` is true -`ASSERT_FALSE(condition);` | `EXPECT_FALSE(condition);` | `condition` is false - -Remember, when they fail, `ASSERT_*` yields a fatal failure and returns from the -current function, while `EXPECT_*` yields a nonfatal failure, allowing the -function to continue running. In either case, an assertion failure means its -containing test fails. - -**Availability**: Linux, Windows, Mac. - -### Binary Comparison - -This section describes assertions that compare two values. - -Fatal assertion | Nonfatal assertion | Verifies ------------------------- | ------------------------ | -------------- -`ASSERT_EQ(val1, val2);` | `EXPECT_EQ(val1, val2);` | `val1 == val2` -`ASSERT_NE(val1, val2);` | `EXPECT_NE(val1, val2);` | `val1 != val2` -`ASSERT_LT(val1, val2);` | `EXPECT_LT(val1, val2);` | `val1 < val2` -`ASSERT_LE(val1, val2);` | `EXPECT_LE(val1, val2);` | `val1 <= val2` -`ASSERT_GT(val1, val2);` | `EXPECT_GT(val1, val2);` | `val1 > val2` -`ASSERT_GE(val1, val2);` | `EXPECT_GE(val1, val2);` | `val1 >= val2` - -Value arguments must be comparable by the assertion's comparison operator or -you'll get a compiler error. We used to require the arguments to support the -`<<` operator for streaming to an `ostream`, but this is no longer necessary. If -`<<` is supported, it will be called to print the arguments when the assertion -fails; otherwise googletest will attempt to print them in the best way it can. -For more details and how to customize the printing of the arguments, see the -[documentation](./advanced.md#teaching-googletest-how-to-print-your-values). - -These assertions can work with a user-defined type, but only if you define the -corresponding comparison operator (e.g., `==` or `<`). Since this is discouraged -by the Google -[C++ Style Guide](https://google.github.io/styleguide/cppguide.html#Operator_Overloading), -you may need to use `ASSERT_TRUE()` or `EXPECT_TRUE()` to assert the equality of -two objects of a user-defined type. - -However, when possible, `ASSERT_EQ(actual, expected)` is preferred to -`ASSERT_TRUE(actual == expected)`, since it tells you `actual` and `expected`'s -values on failure. - -Arguments are always evaluated exactly once. Therefore, it's OK for the -arguments to have side effects. However, as with any ordinary C/C++ function, -the arguments' evaluation order is undefined (i.e., the compiler is free to -choose any order), and your code should not depend on any particular argument -evaluation order. - -`ASSERT_EQ()` does pointer equality on pointers. If used on two C strings, it -tests if they are in the same memory location, not if they have the same value. -Therefore, if you want to compare C strings (e.g. `const char*`) by value, use -`ASSERT_STREQ()`, which will be described later on. In particular, to assert -that a C string is `NULL`, use `ASSERT_STREQ(c_string, NULL)`. Consider using -`ASSERT_EQ(c_string, nullptr)` if c++11 is supported. To compare two `string` -objects, you should use `ASSERT_EQ`. - -When doing pointer comparisons use `*_EQ(ptr, nullptr)` and `*_NE(ptr, nullptr)` -instead of `*_EQ(ptr, NULL)` and `*_NE(ptr, NULL)`. This is because `nullptr` is -typed, while `NULL` is not. See the [FAQ](faq.md) for more details. - -If you're working with floating point numbers, you may want to use the floating -point variations of some of these macros in order to avoid problems caused by -rounding. See [Advanced googletest Topics](advanced.md) for details. - -Macros in this section work with both narrow and wide string objects (`string` -and `wstring`). - -**Availability**: Linux, Windows, Mac. - -**Historical note**: Before February 2016 `*_EQ` had a convention of calling it -as `ASSERT_EQ(expected, actual)`, so lots of existing code uses this order. Now -`*_EQ` treats both parameters in the same way. - -### String Comparison - -The assertions in this group compare two **C strings**. If you want to compare -two `string` objects, use `EXPECT_EQ`, `EXPECT_NE`, and etc instead. - - -| Fatal assertion | Nonfatal assertion | Verifies | -| -------------------------- | ------------------------------ | -------------------------------------------------------- | -| `ASSERT_STREQ(str1,str2);` | `EXPECT_STREQ(str1,str2);` | the two C strings have the same content | -| `ASSERT_STRNE(str1,str2);` | `EXPECT_STRNE(str1,str2);` | the two C strings have different contents | -| `ASSERT_STRCASEEQ(str1,str2);` | `EXPECT_STRCASEEQ(str1,str2);` | the two C strings have the same content, ignoring case | -| `ASSERT_STRCASENE(str1,str2);` | `EXPECT_STRCASENE(str1,str2);` | the two C strings have different contents, ignoring case | - - -Note that "CASE" in an assertion name means that case is ignored. A `NULL` -pointer and an empty string are considered *different*. - -`*STREQ*` and `*STRNE*` also accept wide C strings (`wchar_t*`). If a comparison -of two wide strings fails, their values will be printed as UTF-8 narrow strings. - -**Availability**: Linux, Windows, Mac. - -**See also**: For more string comparison tricks (substring, prefix, suffix, and -regular expression matching, for example), see [this](advanced.md) in the -Advanced googletest Guide. +GoogleTest provides a collection of assertions for verifying the behavior of +your code in various ways. You can check Boolean conditions, compare values +based on relational operators, verify string values, floating-point values, and +much more. There are even assertions that enable you to verify more complex +states by providing custom predicates. For the complete list of assertions +provided by GoogleTest, see the [Assertions Reference](reference/assertions.md). ## Simple Tests @@ -245,7 +149,7 @@ To create a test: 1. Use the `TEST()` macro to define and name a test function. These are ordinary C++ functions that don't return a value. 2. In this function, along with any valid C++ statements you want to include, - use the various googletest assertions to check values. + use the various GoogleTest assertions to check values. 3. The test's result is determined by the assertions; if any assertion in the test fails (either fatally or non-fatally), or if the test crashes, the entire test fails. Otherwise, it succeeds. @@ -258,9 +162,9 @@ TEST(TestSuiteName, TestName) { `TEST()` arguments go from general to specific. The *first* argument is the name of the test suite, and the *second* argument is the test's name within the test -suite. Both names must be valid C++ identifiers, and they should not contain -any underscores (`_`). A test's *full name* consists of its containing test suite and -its individual name. Tests from different test suites can have the same +suite. Both names must be valid C++ identifiers, and they should not contain any +underscores (`_`). A test's *full name* consists of its containing test suite +and its individual name. Tests from different test suites can have the same individual name. For example, let's take a simple integer function: @@ -286,7 +190,7 @@ TEST(FactorialTest, HandlesPositiveInput) { } ``` -googletest groups the test results by test suites, so logically related tests +GoogleTest groups the test results by test suites, so logically related tests should be in the same test suite; in other words, the first argument to their `TEST()` should be the same. In the above example, we have two tests, `HandlesZeroInput` and `HandlesPositiveInput`, that belong to the same test @@ -323,14 +227,14 @@ When using a fixture, use `TEST_F()` instead of `TEST()` as it allows you to access objects and subroutines in the test fixture: ```c++ -TEST_F(TestFixtureName, TestName) { +TEST_F(TestFixtureClassName, TestName) { ... test body ... } ``` -Like `TEST()`, the first argument is the test suite name, but for `TEST_F()` -this must be the name of the test fixture class. You've probably guessed: `_F` -is for fixture. +Unlike `TEST()`, in `TEST_F()` the first argument must be the name of the test +fixture class. (`_F` stands for "Fixture"). No test suite name is specified for +this macro. Unfortunately, the C++ macro system does not allow us to create a single macro that can handle both types of tests. Using the wrong macro causes a compiler @@ -340,12 +244,12 @@ Also, you must first define a test fixture class before using it in a `TEST_F()`, or you'll get the compiler error "`virtual outside class declaration`". -For each test defined with `TEST_F()`, googletest will create a *fresh* test -fixture at runtime, immediately initialize it via `SetUp()`, run the test, -clean up by calling `TearDown()`, and then delete the test fixture. Note that +For each test defined with `TEST_F()`, GoogleTest will create a *fresh* test +fixture at runtime, immediately initialize it via `SetUp()`, run the test, clean +up by calling `TearDown()`, and then delete the test fixture. Note that different tests in the same test suite have different test fixture objects, and -googletest always deletes a test fixture before it creates the next one. -googletest does **not** reuse the same test fixture for multiple tests. Any +GoogleTest always deletes a test fixture before it creates the next one. +GoogleTest does **not** reuse the same test fixture for multiple tests. Any changes one test makes to the fixture do not affect other tests. As an example, let's write tests for a FIFO queue class named `Queue`, which has @@ -370,6 +274,7 @@ First, define a fixture class. By convention, you should give it the name class QueueTest : public ::testing::Test { protected: void SetUp() override { + // q0_ remains empty q1_.Enqueue(1); q2_.Enqueue(2); q2_.Enqueue(3); @@ -415,12 +320,12 @@ The above uses both `ASSERT_*` and `EXPECT_*` assertions. The rule of thumb is to use `EXPECT_*` when you want the test to continue to reveal more errors after the assertion failure, and use `ASSERT_*` when continuing after failure doesn't make sense. For example, the second assertion in the `Dequeue` test is -`ASSERT_NE(nullptr, n)`, as we need to dereference the pointer `n` later, which +`ASSERT_NE(n, nullptr)`, as we need to dereference the pointer `n` later, which would lead to a segfault when `n` is `NULL`. When these tests run, the following happens: -1. googletest constructs a `QueueTest` object (let's call it `t1`). +1. GoogleTest constructs a `QueueTest` object (let's call it `t1`). 2. `t1.SetUp()` initializes `t1`. 3. The first test (`IsEmptyInitially`) runs on `t1`. 4. `t1.TearDown()` cleans up after the test finishes. @@ -432,18 +337,18 @@ When these tests run, the following happens: ## Invoking the Tests -`TEST()` and `TEST_F()` implicitly register their tests with googletest. So, +`TEST()` and `TEST_F()` implicitly register their tests with GoogleTest. So, unlike with many other C++ testing frameworks, you don't have to re-list all your defined tests in order to run them. After defining your tests, you can run them with `RUN_ALL_TESTS()`, which returns `0` if all the tests are successful, or `1` otherwise. Note that -`RUN_ALL_TESTS()` runs *all tests* in your link unit--they can be from -different test suites, or even different source files. +`RUN_ALL_TESTS()` runs *all tests* in your link unit--they can be from different +test suites, or even different source files. When invoked, the `RUN_ALL_TESTS()` macro: -* Saves the state of all googletest flags. +* Saves the state of all GoogleTest flags. * Creates a test fixture object for the first test. @@ -455,7 +360,7 @@ When invoked, the `RUN_ALL_TESTS()` macro: * Deletes the fixture. -* Restores the state of all googletest flags. +* Restores the state of all GoogleTest flags. * Repeats the above steps for the next test, until all tests have run. @@ -469,14 +374,14 @@ If a fatal failure happens the subsequent steps will be skipped. > return the value of `RUN_ALL_TESTS()`. > > Also, you should call `RUN_ALL_TESTS()` only **once**. Calling it more than -> once conflicts with some advanced googletest features (e.g., thread-safe +> once conflicts with some advanced GoogleTest features (e.g., thread-safe > [death tests](advanced.md#death-tests)) and thus is not supported. **Availability**: Linux, Windows, Mac. ## Writing the main() Function -Most users should _not_ need to write their own `main` function and instead link +Most users should *not* need to write their own `main` function and instead link with `gtest_main` (as opposed to with `gtest`), which defines a suitable entry point. See the end of this section for details. The remainder of this section should only apply when you need to do something custom before the tests run that @@ -490,7 +395,7 @@ You can start from this boilerplate: ```c++ #include "this/package/foo.h" -#include "gtest/gtest.h" +#include <gtest/gtest.h> namespace my { namespace project { @@ -551,9 +456,9 @@ int main(int argc, char **argv) { ``` The `::testing::InitGoogleTest()` function parses the command line for -googletest flags, and removes all recognized flags. This allows the user to -control a test program's behavior via various flags, which we'll cover in -the [AdvancedGuide](advanced.md). You **must** call this function before calling +GoogleTest flags, and removes all recognized flags. This allows the user to +control a test program's behavior via various flags, which we'll cover in the +[AdvancedGuide](advanced.md). You **must** call this function before calling `RUN_ALL_TESTS()`, or the flags won't be properly initialized. On Windows, `InitGoogleTest()` also works with wide strings, so it can be used @@ -571,7 +476,7 @@ NOTE: `ParseGUnitFlags()` is deprecated in favor of `InitGoogleTest()`. * Google Test is designed to be thread-safe. The implementation is thread-safe on systems where the `pthreads` library is available. It is currently - _unsafe_ to use Google Test assertions from two threads concurrently on + *unsafe* to use Google Test assertions from two threads concurrently on other systems (e.g. Windows). In most tests this is not an issue as usually the assertions are done in the main thread. If you want to help, you can volunteer to implement the necessary synchronization primitives in |