`elixir_test`

Runs ExUnit tests against an elixir_app provider already compiled with mix_env = "test".

Description#

elixir_test depends on exactly one target that provides a complete elixir_app record, such as elixir_library or mix_project. The application must compile with mix_env = "test". During the test action, Once creates a test layout with links to the compiled application and dependency bytecode, then runs the tests without recompiling the application.

That split lets a changed test file rerun tests without recompiling the application for explicitly declared targets. Native discovery uses conservative project-wide inputs, so a test-file change can also invalidate compilation. A changed library source invalidates both the compiled library and the dependent test result. By default, tests run through direct ExUnit with elixir, so a package does not need mix.exs. A mix_project dependency selects Mix mode automatically. Once stages declared project, configuration, data, tool, test, and lockfile inputs into an isolated project before running mix test --no-compile --no-deps-check. Library bytecode must already be built by Once in both modes. Mix mode retains native test aliases while consuming the already-compiled application. It loads modules used by Mix's recompilation probes without rerunning project compilers. Application resources, compile metadata, and protocol consolidation outputs are staged as explicit action inputs, including when a previous scratch directory has been removed. Command output is streamed to log artifacts rather than retained in memory. Mix-mode summaries come from structured ExUnit formatter events rather than log text. Skipped tests count once, excluded tests are omitted from executed totals, and invalid tests caused by failed setup count as failures. This avoids differences between Elixir versions and summary-looking test output.

Attributes#

Attribute	Type	Required	Default	Description
`_mix_test_defaults`	bool	no	`false`	Resolver-owned marker that delegates test path and file-pattern selection to Mix
`mix_config`	string	no	empty	Optional package-relative Mix project file. When omitted, tests run through direct ExUnit without requiring a Mix project
`lockfile`	string	no	`mix.lock`	Package-relative lockfile staged when present
`config`	list<string>	no	`["config/*/.exs"]`	Config file globs included in the test action key
`config_files`	list<string>	no	`[]`	Buck-compatible alias for additional config file globs
`data`	list<string>	no	`[]`	Data file globs available during tests
`os_env`	map<string, string>	no	`{}`	Buck-compatible environment variables exported before running tests
`env_inherit`	list<string>	no	`[]`	Host environment variable names inherited before explicit `env` values
`env`	map<string, string>	no	`{}`	Environment variables exported before running tests
`test_args`	list<string>	no	`[]`	Additional arguments appended to the test runner
`setup_tasks`	list<list<string>>	no	`[]`	Ordered Mix tasks and their exact arguments run before the test task
`elixir_opts`	list<string>	no	`[]`	Bazel-compatible options passed to the direct Elixir interpreter before test files
`setup`	string	no	empty	Shell snippet run after the test environment is prepared and before ExUnit starts
`no_start`	bool	no	`false`	Pass `--no-start` to `mix test` when `mix_config` enables Mix mode
`ez_deps`	list<string>	no	`[]`	Reserved archive dependencies
`tools`	list<string>	no	`[]`	Package-relative executable or support-file globs available to the test setup command
`labels`	list<string>	no	`[]`	Labels exposed through `once_test_info`
`timeout_ms`	int	no	empty	Optional test timeout in milliseconds
`cacheable`	bool	no	`true`	Whether successful test results may be restored from the action cache

A non-empty ez_deps value fails validation because Once cannot place Erlang archives on the ExUnit code path.

elixir_opts applies only to direct ExUnit mode. When mix_config selects Mix mode, use test_args; combining Mix mode with elixir_opts fails validation. setup_tasks also requires Mix mode. Set cacheable = false when setup or the test suite must exercise an external service on every invocation. Uncacheable tests inherit the host environment, home directory, and tool search path. Native discovery selects this mode automatically; explicitly declared targets retain the cacheable default.

Each setup task is an exact argument vector. Do not include the mix executable:

toml

setup_tasks = [
  ["ecto.create", "--quiet", "--no-compile", "--no-deps-check"],
  ["ecto.migrate", "--quiet", "--no-compile", "--no-deps-check"],
]

Dependency Edges#

Edge	Accepts	Description
`deps`	`elixir_app`	The test-environment Elixir application under test

Providers#

The target emits once_test_info.

Capabilities#

Capability	Output groups
`test`	`default`, `test_results`, `logs`

Example#

toml

[[target]]
name = "greeting"
kind = "elixir_library"
srcs = ["lib/**/*.ex"]

[target.attrs]
app_name = "greeting"
mix_env = "test"

[[target]]
name = "greeting_test"
kind = "elixir_test"
srcs = ["test/**/*_test.exs"]
deps = ["./greeting"]

[target.attrs]
labels = ["unit"]