Source release 19.5.0
This commit is contained in:
113
third_party/googletest/docs/faq.md
vendored
113
third_party/googletest/docs/faq.md
vendored
@@ -1,9 +1,9 @@
|
||||
# Googletest FAQ
|
||||
# GoogleTest FAQ
|
||||
|
||||
## Why should test suite names and test names not contain underscore?
|
||||
|
||||
{: .callout .note}
|
||||
Note: Googletest reserves underscore (`_`) for special purpose keywords, such as
|
||||
Note: GoogleTest reserves underscore (`_`) for special-purpose keywords, such as
|
||||
[the `DISABLED_` prefix](advanced.md#temporarily-disabling-tests), in addition
|
||||
to the following rationale.
|
||||
|
||||
@@ -33,9 +33,9 @@ contains `_`?
|
||||
`TestSuiteName_Bar__Test`, which is invalid.
|
||||
|
||||
So clearly `TestSuiteName` and `TestName` cannot start or end with `_`
|
||||
(Actually, `TestSuiteName` can start with `_` -- as long as the `_` isn't
|
||||
followed by an upper-case letter. But that's getting complicated. So for
|
||||
simplicity we just say that it cannot start with `_`.).
|
||||
(Actually, `TestSuiteName` can start with `_`—as long as the `_` isn't followed
|
||||
by an upper-case letter. But that's getting complicated. So for simplicity we
|
||||
just say that it cannot start with `_`.).
|
||||
|
||||
It may seem fine for `TestSuiteName` and `TestName` to contain `_` in the
|
||||
middle. However, consider this:
|
||||
@@ -50,15 +50,15 @@ Now, the two `TEST`s will both generate the same class
|
||||
|
||||
So for simplicity, we just ask the users to avoid `_` in `TestSuiteName` and
|
||||
`TestName`. The rule is more constraining than necessary, but it's simple and
|
||||
easy to remember. It also gives googletest some wiggle room in case its
|
||||
easy to remember. It also gives GoogleTest some wiggle room in case its
|
||||
implementation needs to change in the future.
|
||||
|
||||
If you violate the rule, there may not be immediate consequences, but your test
|
||||
may (just may) break with a new compiler (or a new version of the compiler you
|
||||
are using) or with a new version of googletest. Therefore it's best to follow
|
||||
are using) or with a new version of GoogleTest. Therefore it's best to follow
|
||||
the rule.
|
||||
|
||||
## Why does googletest support `EXPECT_EQ(NULL, ptr)` and `ASSERT_EQ(NULL, ptr)` but not `EXPECT_NE(NULL, ptr)` and `ASSERT_NE(NULL, ptr)`?
|
||||
## Why does GoogleTest support `EXPECT_EQ(NULL, ptr)` and `ASSERT_EQ(NULL, ptr)` but not `EXPECT_NE(NULL, ptr)` and `ASSERT_NE(NULL, ptr)`?
|
||||
|
||||
First of all, you can use `nullptr` with each of these macros, e.g.
|
||||
`EXPECT_EQ(ptr, nullptr)`, `EXPECT_NE(ptr, nullptr)`, `ASSERT_EQ(ptr, nullptr)`,
|
||||
@@ -68,7 +68,7 @@ because `nullptr` does not have the type problems that `NULL` does.
|
||||
Due to some peculiarity of C++, it requires some non-trivial template meta
|
||||
programming tricks to support using `NULL` as an argument of the `EXPECT_XX()`
|
||||
and `ASSERT_XX()` macros. Therefore we only do it where it's most needed
|
||||
(otherwise we make the implementation of googletest harder to maintain and more
|
||||
(otherwise we make the implementation of GoogleTest harder to maintain and more
|
||||
error-prone than necessary).
|
||||
|
||||
Historically, the `EXPECT_EQ()` macro took the *expected* value as its first
|
||||
@@ -128,30 +128,9 @@ both approaches a try. Practice is a much better way to grasp the subtle
|
||||
differences between the two tools. Once you have some concrete experience, you
|
||||
can much more easily decide which one to use the next time.
|
||||
|
||||
## I got some run-time errors about invalid proto descriptors when using `ProtocolMessageEquals`. Help!
|
||||
|
||||
{: .callout .note}
|
||||
**Note:** `ProtocolMessageEquals` and `ProtocolMessageEquiv` are *deprecated*
|
||||
now. Please use `EqualsProto`, etc instead.
|
||||
|
||||
`ProtocolMessageEquals` and `ProtocolMessageEquiv` were redefined recently and
|
||||
are now less tolerant of invalid protocol buffer definitions. In particular, if
|
||||
you have a `foo.proto` that doesn't fully qualify the type of a protocol message
|
||||
it references (e.g. `message<Bar>` where it should be `message<blah.Bar>`), you
|
||||
will now get run-time errors like:
|
||||
|
||||
```
|
||||
... descriptor.cc:...] Invalid proto descriptor for file "path/to/foo.proto":
|
||||
... descriptor.cc:...] blah.MyMessage.my_field: ".Bar" is not defined.
|
||||
```
|
||||
|
||||
If you see this, your `.proto` file is broken and needs to be fixed by making
|
||||
the types fully qualified. The new definition of `ProtocolMessageEquals` and
|
||||
`ProtocolMessageEquiv` just happen to reveal your bug.
|
||||
|
||||
## My death test modifies some state, but the change seems lost after the death test finishes. Why?
|
||||
|
||||
Death tests (`EXPECT_DEATH`, etc) are executed in a sub-process s.t. the
|
||||
Death tests (`EXPECT_DEATH`, etc.) are executed in a sub-process s.t. the
|
||||
expected crash won't kill the test program (i.e. the parent process). As a
|
||||
result, any in-memory side effects they incur are observable in their respective
|
||||
sub-processes, but not in the parent process. You can think of them as running
|
||||
@@ -162,7 +141,7 @@ methods, the parent process will think the calls have never occurred. Therefore,
|
||||
you may want to move your `EXPECT_CALL` statements inside the `EXPECT_DEATH`
|
||||
macro.
|
||||
|
||||
## EXPECT_EQ(htonl(blah), blah_blah) generates weird compiler errors in opt mode. Is this a googletest bug?
|
||||
## EXPECT_EQ(htonl(blah), blah_blah) generates weird compiler errors in opt mode. Is this a GoogleTest bug?
|
||||
|
||||
Actually, the bug is in `htonl()`.
|
||||
|
||||
@@ -192,16 +171,16 @@ class Foo {
|
||||
};
|
||||
```
|
||||
|
||||
You also need to define it *outside* of the class body in `foo.cc`:
|
||||
you also need to define it *outside* of the class body in `foo.cc`:
|
||||
|
||||
```c++
|
||||
const int Foo::kBar; // No initializer here.
|
||||
```
|
||||
|
||||
Otherwise your code is **invalid C++**, and may break in unexpected ways. In
|
||||
particular, using it in googletest comparison assertions (`EXPECT_EQ`, etc) will
|
||||
generate an "undefined reference" linker error. The fact that "it used to work"
|
||||
doesn't mean it's valid. It just means that you were lucky. :-)
|
||||
particular, using it in GoogleTest comparison assertions (`EXPECT_EQ`, etc.)
|
||||
will generate an "undefined reference" linker error. The fact that "it used to
|
||||
work" doesn't mean it's valid. It just means that you were lucky. :-)
|
||||
|
||||
If the declaration of the static data member is `constexpr` then it is
|
||||
implicitly an `inline` definition, and a separate definition in `foo.cc` is not
|
||||
@@ -225,7 +204,7 @@ cases may want to use the same or slightly different fixtures. For example, you
|
||||
may want to make sure that all of a GUI library's test suites don't leak
|
||||
important system resources like fonts and brushes.
|
||||
|
||||
In googletest, you share a fixture among test suites by putting the shared logic
|
||||
In GoogleTest, you share a fixture among test suites by putting the shared logic
|
||||
in a base test fixture, then deriving from that base a separate fixture for each
|
||||
test suite that wants to use this common logic. You then use `TEST_F()` to write
|
||||
tests using each derived fixture.
|
||||
@@ -264,10 +243,10 @@ TEST_F(FooTest, Baz) { ... }
|
||||
```
|
||||
|
||||
If necessary, you can continue to derive test fixtures from a derived fixture.
|
||||
googletest has no limit on how deep the hierarchy can be.
|
||||
GoogleTest has no limit on how deep the hierarchy can be.
|
||||
|
||||
For a complete example using derived test fixtures, see
|
||||
[sample5_unittest.cc](https://github.com/google/googletest/blob/master/googletest/samples/sample5_unittest.cc).
|
||||
[sample5_unittest.cc](https://github.com/google/googletest/blob/main/googletest/samples/sample5_unittest.cc).
|
||||
|
||||
## My compiler complains "void value not ignored as it ought to be." What does this mean?
|
||||
|
||||
@@ -278,7 +257,7 @@ disabled by our build system. Please see more details
|
||||
|
||||
## My death test hangs (or seg-faults). How do I fix it?
|
||||
|
||||
In googletest, death tests are run in a child process and the way they work is
|
||||
In GoogleTest, death tests are run in a child process and the way they work is
|
||||
delicate. To write death tests you really need to understand how they work—see
|
||||
the details at [Death Assertions](reference/assertions.md#death) in the
|
||||
Assertions Reference.
|
||||
@@ -305,13 +284,13 @@ bullet - sorry!
|
||||
|
||||
## Should I use the constructor/destructor of the test fixture or SetUp()/TearDown()? {#CtorVsSetUp}
|
||||
|
||||
The first thing to remember is that googletest does **not** reuse the same test
|
||||
fixture object across multiple tests. For each `TEST_F`, googletest will create
|
||||
The first thing to remember is that GoogleTest does **not** reuse the same test
|
||||
fixture object across multiple tests. For each `TEST_F`, GoogleTest will create
|
||||
a **fresh** test fixture object, immediately call `SetUp()`, run the test body,
|
||||
call `TearDown()`, and then delete the test fixture object.
|
||||
|
||||
When you need to write per-test set-up and tear-down logic, you have the choice
|
||||
between using the test fixture constructor/destructor or `SetUp()/TearDown()`.
|
||||
between using the test fixture constructor/destructor or `SetUp()`/`TearDown()`.
|
||||
The former is usually preferred, as it has the following benefits:
|
||||
|
||||
* By initializing a member variable in the constructor, we have the option to
|
||||
@@ -328,7 +307,7 @@ You may still want to use `SetUp()/TearDown()` in the following cases:
|
||||
|
||||
* C++ does not allow virtual function calls in constructors and destructors.
|
||||
You can call a method declared as virtual, but it will not use dynamic
|
||||
dispatch, it will use the definition from the class the constructor of which
|
||||
dispatch. It will use the definition from the class the constructor of which
|
||||
is currently executing. This is because calling a virtual method before the
|
||||
derived class constructor has a chance to run is very dangerous - the
|
||||
virtual method might operate on uninitialized data. Therefore, if you need
|
||||
@@ -345,14 +324,14 @@ You may still want to use `SetUp()/TearDown()` in the following cases:
|
||||
that many standard libraries (like STL) may throw when exceptions are
|
||||
enabled in the compiler. Therefore you should prefer `TearDown()` if you
|
||||
want to write portable tests that work with or without exceptions.
|
||||
* The googletest team is considering making the assertion macros throw on
|
||||
* The GoogleTest team is considering making the assertion macros throw on
|
||||
platforms where exceptions are enabled (e.g. Windows, Mac OS, and Linux
|
||||
client-side), which will eliminate the need for the user to propagate
|
||||
failures from a subroutine to its caller. Therefore, you shouldn't use
|
||||
googletest assertions in a destructor if your code could run on such a
|
||||
GoogleTest assertions in a destructor if your code could run on such a
|
||||
platform.
|
||||
|
||||
## The compiler complains "no matching function to call" when I use ASSERT_PRED*. How do I fix it?
|
||||
## The compiler complains "no matching function to call" when I use `ASSERT_PRED*`. How do I fix it?
|
||||
|
||||
See details for [`EXPECT_PRED*`](reference/assertions.md#EXPECT_PRED) in the
|
||||
Assertions Reference.
|
||||
@@ -375,7 +354,7 @@ they write
|
||||
This is **wrong and dangerous**. The testing services needs to see the return
|
||||
value of `RUN_ALL_TESTS()` in order to determine if a test has passed. If your
|
||||
`main()` function ignores it, your test will be considered successful even if it
|
||||
has a googletest assertion failure. Very bad.
|
||||
has a GoogleTest assertion failure. Very bad.
|
||||
|
||||
We have decided to fix this (thanks to Michael Chastain for the idea). Now, your
|
||||
code will no longer be able to ignore `RUN_ALL_TESTS()` when compiled with
|
||||
@@ -410,7 +389,7 @@ C++ is case-sensitive. Did you spell it as `Setup()`?
|
||||
Similarly, sometimes people spell `SetUpTestSuite()` as `SetupTestSuite()` and
|
||||
wonder why it's never called.
|
||||
|
||||
## I have several test suites which share the same test fixture logic, do I have to define a new test fixture class for each of them? This seems pretty tedious.
|
||||
## I have several test suites which share the same test fixture logic; do I have to define a new test fixture class for each of them? This seems pretty tedious.
|
||||
|
||||
You don't have to. Instead of
|
||||
|
||||
@@ -440,14 +419,14 @@ TEST_F(BarTest, Abc) { ... }
|
||||
TEST_F(BarTest, Def) { ... }
|
||||
```
|
||||
|
||||
## googletest output is buried in a whole bunch of LOG messages. What do I do?
|
||||
## GoogleTest output is buried in a whole bunch of LOG messages. What do I do?
|
||||
|
||||
The googletest output is meant to be a concise and human-friendly report. If
|
||||
your test generates textual output itself, it will mix with the googletest
|
||||
The GoogleTest output is meant to be a concise and human-friendly report. If
|
||||
your test generates textual output itself, it will mix with the GoogleTest
|
||||
output, making it hard to read. However, there is an easy solution to this
|
||||
problem.
|
||||
|
||||
Since `LOG` messages go to stderr, we decided to let googletest output go to
|
||||
Since `LOG` messages go to stderr, we decided to let GoogleTest output go to
|
||||
stdout. This way, you can easily separate the two using redirection. For
|
||||
example:
|
||||
|
||||
@@ -520,7 +499,7 @@ TEST(MyDeathTest, CompoundStatement) {
|
||||
|
||||
## I have a fixture class `FooTest`, but `TEST_F(FooTest, Bar)` gives me error ``"no matching function for call to `FooTest::FooTest()'"``. Why?
|
||||
|
||||
Googletest needs to be able to create objects of your test fixture class, so it
|
||||
GoogleTest needs to be able to create objects of your test fixture class, so it
|
||||
must have a default constructor. Normally the compiler will define one for you.
|
||||
However, there are cases where you have to define your own:
|
||||
|
||||
@@ -545,11 +524,11 @@ The new NPTL thread library doesn't suffer from this problem, as it doesn't
|
||||
create a manager thread. However, if you don't control which machine your test
|
||||
runs on, you shouldn't depend on this.
|
||||
|
||||
## Why does googletest require the entire test suite, instead of individual tests, to be named *DeathTest when it uses ASSERT_DEATH?
|
||||
## Why does GoogleTest require the entire test suite, instead of individual tests, to be named `*DeathTest` when it uses `ASSERT_DEATH`?
|
||||
|
||||
googletest does not interleave tests from different test suites. That is, it
|
||||
GoogleTest does not interleave tests from different test suites. That is, it
|
||||
runs all tests in one test suite first, and then runs all tests in the next test
|
||||
suite, and so on. googletest does this because it needs to set up a test suite
|
||||
suite, and so on. GoogleTest does this because it needs to set up a test suite
|
||||
before the first test in it is run, and tear it down afterwards. Splitting up
|
||||
the test case would require multiple set-up and tear-down processes, which is
|
||||
inefficient and makes the semantics unclean.
|
||||
@@ -570,7 +549,7 @@ interleave tests from different test suites, we need to run all tests in the
|
||||
`FooTest` case before running any test in the `BarTest` case. This contradicts
|
||||
with the requirement to run `BarTest.DefDeathTest` before `FooTest.Uvw`.
|
||||
|
||||
## But I don't like calling my entire test suite \*DeathTest when it contains both death tests and non-death tests. What do I do?
|
||||
## But I don't like calling my entire test suite `*DeathTest` when it contains both death tests and non-death tests. What do I do?
|
||||
|
||||
You don't have to, but if you like, you may split up the test suite into
|
||||
`FooTest` and `FooDeathTest`, where the names make it clear that they are
|
||||
@@ -588,11 +567,11 @@ TEST_F(FooDeathTest, Uvw) { ... EXPECT_DEATH(...) ... }
|
||||
TEST_F(FooDeathTest, Xyz) { ... ASSERT_DEATH(...) ... }
|
||||
```
|
||||
|
||||
## googletest prints the LOG messages in a death test's child process only when the test fails. How can I see the LOG messages when the death test succeeds?
|
||||
## GoogleTest prints the LOG messages in a death test's child process only when the test fails. How can I see the LOG messages when the death test succeeds?
|
||||
|
||||
Printing the LOG messages generated by the statement inside `EXPECT_DEATH()`
|
||||
makes it harder to search for real problems in the parent's log. Therefore,
|
||||
googletest only prints them when the death test has failed.
|
||||
GoogleTest only prints them when the death test has failed.
|
||||
|
||||
If you really need to see such LOG messages, a workaround is to temporarily
|
||||
break the death test (e.g. by changing the regex pattern it is expected to
|
||||
@@ -607,11 +586,11 @@ defined such that we can print a value of `FooType`.
|
||||
|
||||
In addition, if `FooType` is declared in a name space, the `<<` operator also
|
||||
needs to be defined in the *same* name space. See
|
||||
[Tip of the Week #49](http://abseil.io/tips/49) for details.
|
||||
[Tip of the Week #49](https://abseil.io/tips/49) for details.
|
||||
|
||||
## How do I suppress the memory leak messages on Windows?
|
||||
|
||||
Since the statically initialized googletest singleton requires allocations on
|
||||
Since the statically initialized GoogleTest singleton requires allocations on
|
||||
the heap, the Visual C++ memory leak detector will report memory leaks at the
|
||||
end of the program run. The easiest way to avoid this is to use the
|
||||
`_CrtMemCheckpoint` and `_CrtMemDumpAllObjectsSince` calls to not report any
|
||||
@@ -625,13 +604,13 @@ things accordingly, you are leaking test-only logic into production code and
|
||||
there is no easy way to ensure that the test-only code paths aren't run by
|
||||
mistake in production. Such cleverness also leads to
|
||||
[Heisenbugs](https://en.wikipedia.org/wiki/Heisenbug). Therefore we strongly
|
||||
advise against the practice, and googletest doesn't provide a way to do it.
|
||||
advise against the practice, and GoogleTest doesn't provide a way to do it.
|
||||
|
||||
In general, the recommended way to cause the code to behave differently under
|
||||
test is [Dependency Injection](http://en.wikipedia.org/wiki/Dependency_injection). You can inject
|
||||
test is [Dependency Injection](https://en.wikipedia.org/wiki/Dependency_injection). You can inject
|
||||
different functionality from the test and from the production code. Since your
|
||||
production code doesn't link in the for-test logic at all (the
|
||||
[`testonly`](http://docs.bazel.build/versions/master/be/common-definitions.html#common.testonly) attribute for BUILD targets helps to ensure
|
||||
[`testonly`](https://docs.bazel.build/versions/master/be/common-definitions.html#common.testonly) attribute for BUILD targets helps to ensure
|
||||
that), there is no danger in accidentally running it.
|
||||
|
||||
However, if you *really*, *really*, *really* have no choice, and if you follow
|
||||
@@ -654,7 +633,7 @@ the `--gtest_also_run_disabled_tests` flag.
|
||||
Yes.
|
||||
|
||||
The rule is **all test methods in the same test suite must use the same fixture
|
||||
class.** This means that the following is **allowed** because both tests use the
|
||||
class**. This means that the following is **allowed** because both tests use the
|
||||
same fixture class (`::testing::Test`).
|
||||
|
||||
```c++
|
||||
@@ -672,7 +651,7 @@ TEST(CoolTest, DoSomething) {
|
||||
```
|
||||
|
||||
However, the following code is **not allowed** and will produce a runtime error
|
||||
from googletest because the test methods are using different test fixture
|
||||
from GoogleTest because the test methods are using different test fixture
|
||||
classes with the same test suite name.
|
||||
|
||||
```c++
|
||||
|
||||
Reference in New Issue
Block a user