Testing

fzf has two distinct test suites: Go unit tests and Ruby + tmux integration tests. They cover different layers and are run separately.

Go unit tests

make test

Under the hood that runs:

go test -v -tags "$(TAGS)" \
    github.com/junegunn/fzf/src \
    github.com/junegunn/fzf/src/algo \
    github.com/junegunn/fzf/src/tui \
    github.com/junegunn/fzf/src/util

Test files live next to their subjects:

Subject	Test file
src/algo/algo.go	src/algo/algo_test.go
src/algo/indexbyte2_*.go	src/algo/indexbyte2_test.go
src/ansi.go	src/ansi_test.go
src/cache.go	src/cache_test.go
src/chunklist.go	src/chunklist_test.go
src/history.go	src/history_test.go
src/item.go	src/item_test.go
src/merger.go	src/merger_test.go
src/options.go	src/options_test.go
src/pattern.go	src/pattern_test.go
src/reader.go	src/reader_test.go
src/result.go	src/result_test.go
src/terminal.go	src/terminal_test.go
src/tokenizer.go	src/tokenizer_test.go
src/tui/light.go	src/tui/light_test.go
src/tui/tcell.go	src/tui/tcell_test.go
src/tui/tui.go	src/tui/tui_test.go
src/util/*.go	src/util/*_test.go
src/options_pprof.go	src/options_pprof_test.go

The CI workflow also runs fuzz tests on the SIMD IndexByteTwo helpers in src/algo/:

go test ./src/algo/ -fuzz=FuzzIndexByteTwo -fuzztime=5s
go test ./src/algo/ -fuzz=FuzzLastIndexByteTwo -fuzztime=5s

Benchmarks

make bench

Runs go test -run=Bench -bench=. -benchmem inside src/. Useful when changing the matcher or the chunk-list snapshot path.

Ruby + tmux integration tests

make itest

This is the primary regression suite for everything user-visible: rendering, key bindings, actions, preview, popup mode, shell integration. The harness:

• Lives under test/ (test_core.rb, test_layout.rb, test_preview.rb, test_filter.rb, test_exec.rb, test_raw.rb, test_server.rb, test_shell_integration.rb).
• Uses helpers in test/lib/ to drive a real tmux pane: it sends keystrokes, captures the pane, and asserts on the rendered output.
• Must be invoked inside an existing tmux session. The CI workflow runs tmux new-session -d first.

A typical test (from test/test_core.rb) opens a tmux pane, types a query, presses enter, and asserts on what was printed:

def test_basic_filter
  tmux.send_keys "(echo 1; echo 2; echo 3) | fzf -q 2", :Enter
  tmux.until { |lines| lines[-1].include?('2') }
  tmux.send_keys :Enter
  assert_equal '2', tmux.capture
end

Run a single test:

ruby test/runner.rb --name test_basic_filter
ruby test/runner.rb --verbose

Pass FZF_DEFAULT_OPTS= and other env vars exactly as the production binary would consume them.

Shell integration tests

test/test_shell_integration.rb exercises the embedded Bash, Zsh, and Fish scripts. The CI workflow installs zsh fish tmux shfmt so all three shells are available. Skips kick in if a particular shell is missing on your machine.

Vim plugin tests

test/vim/ contains a minimal Vim-based smoke test for plugin/fzf.vim.

Linting

make lint

This runs three checks:

1. gofmt -s -d src — must produce no diff.
2. bundle exec rubocop -a --require rubocop-minitest --require rubocop-performance — auto-fixes and asserts clean.
3. shell/update.sh --check against the bash scripts — asserts the include-directive blocks are in sync with shell/common.sh.

Coverage

There is no formal coverage target, but in practice:

• src/algo is heavily covered by unit tests.
• src/options is covered by src/options_test.go (parser cases) plus the integration suite.
• src/terminal is mostly covered by integration tests; the unit test only covers small helpers.
• The algo SIMD helpers have both unit tests and fuzz tests.