Testing Go Applications

Question 1

Does go provide out of the box tooling for unit test?

Answer 1

Yes. No need to install 3rd party packages to do that.

Question 2

What about assertions, does it provide a good support?

Answer 2

Not much… that was intentional since the simplest assertion can be an if.

Question 3

What are the three types of unit test in go? What each does?

Answer 3

Test, Benchmark and example.
Test = unit, integration and end to end
Benchmark = performance
Example = Documentation (it runs the test and include in the go docs).

Question 4

How does the test tooling identify a test file in go? What about the package? Are these files included in production binaries?

Answer 4

They are suffixed with _test.go. Same thing for package. Not included in production binaries.

Question 5

How does the test tooling identify a test method in go? What is the only parameter it requires?

Answer 5

They are PREFIXED with Test. A pointer to *testing.T

Question 6

What are the 4 packages that the standard library offers for testing?

Answer 6

testing (the most common one), testing/quick (black box testing, e.g testing a package without knowing its internals, testing/iotest (helpers for readers and writers) and net/http/httptest (simulate request, responde recorder, test servers for real http requests).

Question 7

What are the most popular community packages for testing in go and what they are used for?

Answer 7

• Testify (has better assertion mechanisms)
• Ginko (bdd tests for go)
• GoConvey (browser-based test results viewer)
• httpexcept (helps with end-to-end tests for rest apis)
• gomock (allow mocking in go)
• go-sqlmock mockable in-memory database

Question 8

How to do a whitebox testing in go?

Answer 8

Use the same module name as the production code (so you can access internals of the package). Also you don’t need to import the under-test package since the prod code and the tests are under the same package.

Question 9

How to declare a public function in go?

Answer 9

Start the function name with a Upper case letter.

Question 10

Should we put end-to-end tests or integration tests in the same folder as the production files that are going to be tested?

Answer 10

No. They should be placed somewhere else since they are testing multiple files at once.

Question 11

What are the two types of test failures reporting? What are the prefix of the first type?

Answer 11

Immediate (no code run after this) and non-immediate failure (reports a failure at the end but the test execution in that file goes on)
Immediate failures are prefixed with Fatal (and the exception is FailNow()).

Question 12

How to run all tests in the directory with verbose output?

Answer 12

got test -v

Question 13

How to run test in specific packages?

Answer 13

go test pkgName

Question 14

How to run tests in the current and descendant directories?

Answer 14

go test ./…

Question 15

How to run tests that matches filenames that matches a regexp?

Answer 15

go test -run regexp

Question 16

How to print information about a command line verb?

Answer 16

e.g: go help test

Question 17

How is the test suite name printed in the go test command?

Answer 17

the name of module (and sub modules)

Question 18

How to generate coverage reports in html? How to read it?

Answer 18

go test -coverprofile count.out -covermode count

go tool cover -html count.out

Question 19

What is table driven tests and how is it supported on go?

Answer 19

is an array of scenarios with the inputs and expected output given the inputs. It’s simply an array of scenarios and a loop over the scenarios.. no special keywords.

Question 20

How can I log stuff during the tests?

Answer 20

log and logf

Question 21

How to skip tests in go?

Answer 21

Skip, SkipF and SkipNow

Question 22

What does the t.Run method does?

Answer 22

Allow running tests inside the test method. Useful to test different flavors of the same thing and grouping them in the same method.

Question 23

Can I run tests concurrently? What go does by default?

Answer 23

Yes, just call Parallel. Run sequentially.

Question 24

What is the 2 differences between the declaration of a regular unit test and benchmark tests? What does it provide?

Answer 24

The name of the test is Benchmark and the parameter is *testing.B. Provides property to run our tests N times, provides timers b.StartTimers and provide parallelism via b.RunParallel.

Question 25

How to run bench tests?

Answer 25

go test -bench .

Question 26

What is the default benchmark time provided by go, how to change that?

Answer 26

go bench . -benchtime 10s

Question 27

How does the benchmark testing in go works?

Answer 27

The benchmark is going to run as much operations as possible given the time frame provided by -benchtime (or 1s default).

Question 28

What are the resources mapped by the profiling tests of go?

Answer 28

block, cover, cpu, mem and mutex.

Question 29

How to run profiling tests?

Answer 29

go test run -benchmem (there are other types of profile).