How to check the test coverage?

I'm going to show you two ways of checking the test coverage:

1. From the command line
2. Inside VS Code

From the command line

First head to the learning-go-lib project folder.

The simplest way to check the test code coverage is to run the test command with the -cover flag:

go test ./... -cover

The result should be similar to:

ok      github.com/renato0307/learning-go-lib/finance   0.830s  coverage: 61.4% of statements
ok      github.com/renato0307/learning-go-lib/programming       0.667s  coverage: 35.5% of statements

As you can see, the finance package contains a coverage of 61.4% and the programming package 35.5%.

But if we want to check for details about which lines are covered we need to export the test coverage information to a file:

go test ./...  -coverprofile=coverage.out

To see it visually you can generate an HTML report by running:

go tool cover -html=coverage.out

The command will open the report in the browser:

You can use the drop down in the top to select the file and check for the details. The lines in green are covered by tests and the lines in red are not.

Inside VS Code

When using VS Code you can see directly the code coverage for a specific file:

1. Open the file
2. Run the command "Go: Toggle Test Coverage In Current Package"
3. The lines covered/uncovered will be signalled in green/red

Next

The next section is

1. Increase coverage in the Lib.