* lisp/progmodes/go-ts-mode.el (go-ts-mode--font-lock-settings):
Add font-locking rule for variable names in range clauses.
* test/lisp/progmodes/go-ts-mode-tests.el (go-ts-test-font-lock):
Add font-locking test for go-ts-mode.
* test/lisp/progmodes/go-ts-mode-resources/font-lock.go: New file
for go-ts-mode font-locking tests.