*dev_test* Nvim NVIM REFERENCE MANUAL Writing tests for Nvim *dev-test* Type |gO| to see the table of contents. ============================================================================== Writing tests for Nvim Nvim has a powerful yet simple test framework. It's approximately 7x better than whatever you use at work. Each test starts a new Nvim process (10-30ms) which is discarded after the test finishes. You assert stuff using `t.eq()` and `screen:expect()` (which automatically waits as needed). That's pretty much it. TODO: Expose the test framework as a public interface, for use in 3P plugins: https://github.com/neovim/neovim/issues/34592 ============================================================================== Test framework Tests are broadly divided into unit tests (`test/unit/`), functional tests (`test/functional/`) and old tests (`test/old/testdir/`). - Unit testing is achieved by compiling the tests as a shared library which is loaded and called by [LuaJit FFI](https://luajit.org/ext_ffi.html). - Functional tests are driven by RPC, so they do not require LuaJit (as opposed to Lua). They are essentially "integration" tests, they test the full system. But they are fast. You can learn the [Lua concepts 15 minutes](https://learnxinyminutes.com/docs/lua/), see also |lua-guide|. Use any existing test as a template to start writing new tests, or see |dev-quickstart|. Tests are run by the `/cmake/RunTests.cmake` script using `busted` (a Lua test-runner). For some failures, `.nvimlog` (or `$NVIM_LOG_FILE`) may provide insight. Depending on the presence of binaries (e.g., `xclip`) some tests will be skipped. ============================================================================== Test Layout - `/test/benchmark` : benchmarks - `/test/functional` : functional tests - `/test/unit` : unit tests - `/test/old/testdir` : old tests (from Vim) - `/test/config` : contains `*.in` files which are transformed into `*.lua` files using `configure_file` CMake command: this is for accessing CMake variables in Lua tests. - `/test/includes` : include-files for use by luajit `ffi.cdef` C definitions parser: normally used to make macros not accessible via this mechanism accessible the other way. - `/test/*/preload.lua` : modules preloaded by busted `--helper` option - `/test/**/testutil.lua` : common utility functions in the context of the test runner - `/test/**/testnvim.lua` : common utility functions in the context of the test session (RPC channel to the Nvim child process created by clear() for each test) - `/test/*/**/*_spec.lua` : actual tests. Files that do not end with `_spec.lua` are libraries like `/test/**/testutil.lua`, except that they have some common topic. ============================================================================== Running tests *dev-run-test* EXECUTING TESTS To run all tests (except "old" tests): > make test To run only _unit_ tests: > make unittest To run only _functional_ tests: > make functionaltest LEGACY TESTS To run all legacy Vim tests: > make oldtest To run a _single_ legacy test file you can use either: > # Specify only the test file name, not the full path. make oldtest TEST_FILE=test_syntax.vim or: > make test/old/testdir/test_syntax.vim DEBUGGING TESTS - Each test gets a test id which looks like "T123". This also appears in the log file. Child processes spawned from a test appear in the logs with the _parent_ name followed by "/c". Example: > DBG 2022-06-15T18:37:45.226 T57.58016.0 UI: flush DBG 2022-06-15T18:37:45.226 T57.58016.0 inbuf_poll:442: blocking... events_enabled=0 events_pending=0 DBG 2022-06-15T18:37:45.227 T57.58016.0/c UI: stop INF 2022-06-15T18:37:45.227 T57.58016.0/c os_exit:595: Nvim exit: 0 DBG 2022-06-15T18:37:45.229 T57.58016.0 read_cb:118: closing Stream (0x7fd5d700ea18): EOF (end of file) INF 2022-06-15T18:37:45.229 T57.58016.0 on_proc_exit:400: exited: pid=58017 status=0 stoptime=0 - You can set `$GDB` to [run functional tests under gdbserver](https://github.com/neovim/neovim/pull/1527): >sh GDB=1 TEST_FILE=test/functional/api/buffer_spec.lua TEST_FILTER='nvim_buf_set_text works$' make functionaltest < Read more about |dev-filter-test|. Then, in another terminal: >sh gdb -ex 'target remote localhost:7777' build/bin/nvim < If `$VALGRIND` is also set it will pass `--vgdb=yes` to valgrind instead of starting gdbserver directly. See `nvim_argv` in `test/functional/testnvim.lua`. - Hanging tests can happen due to unexpected "press-enter" prompts. The default screen width is 50 columns. Commands that try to print lines longer than 50 columns in the command-line, e.g. `:edit very...long...path`, will trigger the prompt. Try using a shorter path, or `:silent edit`. - If you can't figure out what is going on, try to visualize the screen. Put this at the beginning of your test: > local Screen = require('test.functional.ui.screen') local screen = Screen.new() screen:attach() < Then put `screen:snapshot_util()` anywhere in your test. See the comments in `test/functional/ui/screen.lua` for more info. DEBUGGING LUA TEST CODE Debugging Lua test code is a bit involved. Get your shopping list ready, you'll need to install and configure: 1. [nvim-dap](https://github.com/mfussenegger/nvim-dap) 2. [local-lua-debugger-vscode](https://github.com/mfussenegger/nvim-dap/wiki/Debug-Adapter-installation#local-lua-debugger-vscode) 3. [nlua](https://github.com/mfussenegger/nlua) 4. [one-small-step-for-vimkind](https://github.com/jbyuki/one-small-step-for-vimkind) (called `osv`) 5. A `nbusted` command in `$PATH`. This command can be a copy of `busted` with `exec '/usr/bin/lua5.1'"` replaced with `"exec '/usr/bin/nlua'"` (or the path to your `nlua`) The setup roughly looks like this: > ┌─────────────────────────┐ │ nvim used for debugging │◄────┐ └─────────────────────────┘ │ │ │ ▼ │ ┌─────────────────┐ │ │ local-lua-debug │ │ └─────────────────┘ │ │ │ ▼ │ ┌─────────┐ │ │ nbusted │ │ └─────────┘ │ │ │ ▼ │ ┌───────────┐ │ │ test-case │ │ └───────────┘ │ │ │ ▼ │ ┌────────────────────┐ │ │ nvim test-instance │ │ └────────────────────┘ │ │ ┌─────┐ │ └──►│ osv │─────────────────┘ └─────┘ With these installed you can use a configuration like this: > local dap = require("dap") local function free_port() local tcp = vim.loop.new_tcp() assert(tcp) tcp:bind('127.0.0.1', 0) local port = tcp:getsockname().port tcp:shutdown() tcp:close() return port end local name = "nvim-test-case" -- arbitrary name local config = { name = name, -- value of type must match the key used in `dap.adapters["local-lua"] = ...` from step 2) type = "local-lua", request = "launch", cwd = "${workspaceFolder}", program = { command = "nbusted", }, args = { "--ignore-lua", "--lazy", "--helper=test/functional/preload.lua", "--lpath=build/?.lua", "--lpath=?.lua", -- path to file to debug, could be replaced with a hardcoded string function() return vim.api.nvim_buf_get_name(0) end, -- You can filter to specific test-case by adding: -- '--filter="' .. test_case_name .. '"', }, env = { OSV_PORT = free_port } } -- Whenever the config is used it needs to launch a second debug session that attaches to `osv` -- This makes it possible to step into `exec_lua` code blocks setmetatable(config, { __call = function(c) ---@param session dap.Session dap.listeners.after.event_initialized["nvim_debug"] = function(session) if session.config.name ~= name then return end dap.listeners.after.event_initialized["nvim_debug"] = nil vim.defer_fn(function() dap.run({ name = "attach-osv", type = "nlua", -- value must match the `dap.adapters` definition key for osv request = "attach", port = session.config.env.OSV_PORT, }) end, 500) end return c end, }) You can either add this configuration to your `dap.configurations.lua` list as described in `:help dap-configuration` or create it dynamically in a user-command or function and call it directly via `dap.run(config)`. The latter is useful if you use treesitter to find the test case around a cursor location with a query like the following and set the `--filter` property to it. >query (function_call name: (identifier) @name (#any-of? @name "describe" "it") arguments: (arguments (string) @str ) ) Limitations: - You need to add the following boilerplate to each spec file where you want to be able to stop at breakpoints within the test-case code: > if os.getenv("LOCAL_LUA_DEBUGGER_VSCODE") == "1" then require("lldebugger").start() end < This is a [local-lua-debugger limitation](https://github.com/tomblind/local-lua-debugger-vscode?tab=readme-ov-file#busted) - You cannot step into code of files which get baked into the nvim binary like the `shared.lua`. ------------------------------------------------------------------------------ Filtering tests *dev-filter-test* FILTER BY NAME Tests can be filtered by setting a pattern of test name to `TEST_FILTER` or `TEST_FILTER_OUT`. > it('foo api',function() ... end) it('bar api',function() ... end) To run only test with filter name: > TEST_FILTER='foo.*api' make functionaltest To run all tests except ones matching a filter: > TEST_FILTER_OUT='foo.*api' make functionaltest FILTER BY FILE To run a _specific_ unit test: > TEST_FILE=test/unit/foo.lua make unittest or > cmake -E env "TEST_FILE=test/unit/foo.lua" cmake --build build --target unittest To run a _specific_ functional test: > TEST_FILE=test/functional/foo.lua make functionaltest or > cmake -E env "TEST_FILE=test/functional/foo.lua" cmake --build build --target functionaltest To _repeat_ a test: > BUSTED_ARGS="--repeat=100 --no-keep-going" TEST_FILE=test/functional/foo_spec.lua make functionaltest or > cmake -E env "TEST_FILE=test/functional/foo_spec.lua" cmake -E env BUSTED_ARGS="--repeat=100 --no-keep-going" cmake --build build --target functionaltest FILTER BY TAG Tests can be "tagged" by adding `#` before a token in the test description. > it('#foo bar baz', function() ... end) it('#foo another test', function() ... end) To run only the tagged tests: > TEST_TAG=foo make functionaltest NOTE: - `TEST_FILE` is not a pattern string like `TEST_TAG` or `TEST_FILTER`. The given value to `TEST_FILE` must be a path to an existing file. - Both `TEST_TAG` and `TEST_FILTER` filter tests by the string descriptions found in `it()` and `describe()`. ============================================================================== Writing tests *dev-write-test* GUIDELINES - Luajit needs to know about type and constant declarations used in function prototypes. The [testutil.lua](https://github.com/neovim/neovim/blob/master/test/unit/testutil.lua) file automatically parses `types.h`, so types used in the tested functions could be moved to it to avoid having to rewrite the declarations in the test files. - `#define` constants must be rewritten `const` or `enum` so they can be "visible" to the tests. - Use `pending()` to skip tests ([example](https://github.com/neovim/neovim/commit/5c1dc0fbe7388528875aff9d7b5055ad718014de#diff-bf80b24c724b0004e8418102f68b0679R18)). Do not silently skip the test with `if-else`. If a functional test depends on some external factor (e.g. the existence of `md5sum` on `$PATH`), _and_ you can't mock or fake the dependency, then skip the test via `pending()` if the external factor is missing. This ensures that the _total_ test-count (success + fail + error + pending) is the same in all environments. - Note: `pending()` is ignored if it is missing an argument, unless it is [contained in an `it()` block](https://github.com/neovim/neovim/blob/d21690a66e7eb5ebef18046c7a79ef898966d786/test/functional/ex_cmds/grep_spec.lua#L11). Provide empty function argument if the `pending()` call is outside `it()` ([example](https://github.com/neovim/neovim/commit/5c1dc0fbe7388528875aff9d7b5055ad718014de#diff-bf80b24c724b0004e8418102f68b0679R18)). WHERE TESTS GO Tests in `/test/unit` and `/test/functional` are divided into groups by the semantic component they are testing. - Unit tests (`test/unit/`) should match 1-to-1 with the structure of `src/nvim/`, because they are testing functions directly. E.g. unit-tests for `src/nvim/undo.c` should live in `test/unit/undo_spec.lua`. - Functional tests (`test/functional/`) are higher-level (plugins, UI, user input) than unit tests; they are organized by concept. - Try to find an existing `test/functional/*/*_spec.lua` group that makes sense, before creating a new one. ------------------------------------------------------------------------------ Fixing tests *dev-fix-test* FIXING HARNESS WARNINGS > Nvim session T123 took 2000 milliseconds to exit > This indicates a likely problem with the test even if it passed! This may indicate a leak, because Nvim waits on uv handles before exiting. Example: https://github.com/neovim/neovim/pull/35768 FIXING LINT FAILURES `make lint` (and `make lintlua`) runs [LuaLS](https://github.com/LuaLS/lua-language-server/wiki/Annotations) on the test code. If a LuaLS/EmmyLS warning must be ignored, specify the warning code. Example: >lua ---@diagnostic disable-next-line: unused-vararg https://github.com/LuaLS/lua-language-server/wiki/Annotations#diagnostic Ignore the smallest applicable scope (e.g. inside a function, not at the top of the file). ============================================================================== Configuration *dev-test-config* (TODO: clean this up, too many variables and some of them are not used anymore.) Test behaviour is affected by environment variables. Currently supported (Functional, Unit, Benchmarks) (when Defined; when set to _1_; when defined, treated as Integer; when defined, treated as String; when defined, treated as Number; !must be defined to function properly): - `BUSTED_ARGS` (F) (U): arguments forwarded to `busted`. - `CC` (U) (S): specifies which C compiler to use to preprocess files. Currently only compilers with gcc-compatible arguments are supported. - `GDB` (F) (D): makes nvim instances to be run under `gdbserver`. It will be accessible on `localhost:7777`: use `gdb build/bin/nvim`, type `target remote :7777` inside. - `GDBSERVER_PORT` (F) (I): overrides port used for `GDB`. - `LOG_DIR` (FU) (S!): specifies where to seek for valgrind and ASAN log files. - `VALGRIND` (F) (D): makes nvim instances to be run under `valgrind`. Log files are named `valgrind-%p.log` in this case. Note that non-empty valgrind log may fail tests. Valgrind arguments may be seen in `/test/functional/testnvim.lua`. May be used in conjunction with `GDB`. - `VALGRIND_LOG` (F) (S): overrides valgrind log file name used for `VALGRIND`. - `TEST_COLORS` (F) (U) (D): enable pretty colors in test runner. Set to true by default. - `TEST_SKIP_FRAGILE` (F) (D): makes test suite skip some fragile tests. - `TEST_TIMEOUT` (FU) (I): specifies maximum time, in seconds, before the test suite run is killed - `NVIM_LUA_NOTRACK` (F) (D): disable reference counting of Lua objects - `NVIM_PRG` (F) (S): path to Nvim executable (default: `build/bin/nvim`). - `NVIM_TEST_MAIN_CDEFS` (U) (1): makes `ffi.cdef` run in main process. This raises a possibility of bugs due to conflicts in header definitions, despite the counters, but greatly speeds up unit tests by not requiring `ffi.cdef` to do parsing of big strings with C definitions. - `NVIM_TEST_PRINT_I` (U) (1): makes `cimport` print preprocessed, but not yet filtered through `formatc` headers. Used to debug `formatc`. Printing is done with the line numbers. - `NVIM_TEST_PRINT_CDEF` (U) (1): makes `cimport` print final lines which will be then passed to `ffi.cdef`. Used to debug errors `ffi.cdef` happens to throw sometimes. - `NVIM_TEST_PRINT_SYSCALLS` (U) (1): makes it print to stderr when syscall wrappers are called and what they returned. Used to debug code which makes unit tests be executed in separate processes. - `NVIM_TEST_RUN_FAILING_TESTS` (U) (1): makes `itp` run tests which are known to fail (marked by setting third argument to `true`). - `NVIM_TEST_CORE_*` (FU) (S): a set of environment variables which specify where to search for core files. Are supposed to be defined all at once. - `NVIM_TEST_CORE_GLOB_DIRECTORY` (FU) (S): directory where core files are located. May be `.`. This directory is then recursively searched for core files. Note: this variable must be defined for any of the following to have any effect. - `NVIM_TEST_CORE_GLOB_RE` (FU) (S): regular expression which must be matched by core files. E.g. `/core[^/]*$`. May be absent, in which case any file is considered to be matched. - `NVIM_TEST_CORE_EXC_RE` (FU) (S): regular expression which excludes certain directories from searching for core files inside. E.g. use `^/%.deps$` to not search inside `/.deps`. If absent, nothing is excluded. - `NVIM_TEST_CORE_DB_CMD` (FU) (S): command to get backtrace out of the debugger. E.g. `gdb -n -batch -ex "thread apply all bt full" "$_NVIM_TEST_APP" -c "$_NVIM_TEST_CORE"`. Defaults to the example command. This debug command may use environment variables `_NVIM_TEST_APP` (path to application which is being debugged: normally either nvim or luajit) and `_NVIM_TEST_CORE` (core file to get backtrace from). - `NVIM_TEST_CORE_RANDOM_SKIP` (FU) (D): makes `check_cores` not check cores after approximately 90% of the tests. Should be used when finding cores is too hard for some reason. Normally (on OS X or when `NVIM_TEST_CORE_GLOB_DIRECTORY` is defined and this variable is not) cores are checked for after each test. - `NVIM_TEST_INTEG` (F) (D): enables integration tests that makes real network calls. By default these tests are skipped. When set to `1`, tests requiring external HTTP requests (e.g `vim.net.request()`) will be run. - `NVIM_TEST_RUN_TESTTEST` (U) (1): allows running `test/unit/testtest_spec.lua` used to check how testing infrastructure works. - `NVIM_TEST_TRACE_LEVEL` (U) (N): specifies unit tests tracing level: - `0` disables tracing (the fastest, but you get no data if tests crash and there no core dump was generated), - `1` leaves only C function calls and returns in the trace (faster than recording everything), - `2` records all function calls, returns and executed Lua source lines. - `NVIM_TEST_TRACE_ON_ERROR` (U) (1): makes unit tests yield trace on error in addition to regular error message. - `NVIM_TEST_MAXTRACE` (U) (N): specifies maximum number of trace lines to keep. Default is 1024. - `OSV_PORT`: (F): launches `osv` listening on the given port within nvim test instances. vim:tw=78:ts=8:sw=4:et:ft=help:norl: