LSP has “marker tests” defined in internal/lsp/testdata, as well as traditional tests.

Marker tests

Marker tests have a standard input file, like internal/lsp/testdata/foo/bar.go, and some may have a corresponding golden file, like internal/lsp/testdata/foo/bar.go.golden. The former is the “input” and the latter is the expected output.

Each input file contains annotations like //@suggestedfix("}", "refactor.rewrite", "Fill anonymous struct"). These annotations are interpreted by test runners to perform certain actions. The expected output after those actions is encoded in the golden file.

When tests are run, each annotation results in a new subtest, which is encoded in the golden file with a heading like,

-- suggestedfix_bar_11_21 --
// expected contents go here
-- suggestedfix_bar_13_20 --
// expected contents go here

The format of these headings vary: they are defined by the Golden function for each annotation. In the case above, the format is: annotation name, file name, annotation line location, annotation character location.

So, if internal/lsp/testdata/foo/bar.go has three suggestedfix annotations, the golden file should have three headers with suggestedfix_bar_xx_yy headings.

To see a list of all available annotations, see the exported “expectations” in tests.go.

To run marker tests,

cd /path/to/tools

# The marker tests are located in "internal/lsp", "internal/lsp/cmd, and
# "internal/lsp/source".
go test ./internal/lsp/...

There are quite a lot of marker tests, so to run one individually, pass the test path and heading into a -run argument:

cd /path/to/tools
go test ./internal/lsp/... -v -run TestLSP/Modules/SuggestedFix/bar_11_21

Resetting marker tests

Sometimes, a change is made to lsp that requires a change to multiple golden files. When this happens, you can run,

cd /path/to/tools