Document options of invoke test command

CONTRIBUTING.md

@@ -31,9 +31,15 @@ Tests are handled with [pytest](https://docs.pytest.org/en/stable/index.html). T
 Once `h5grove` is installed in editable mode, run the tests with
 
 ```
-invoke test
+invoke test [--options]
 ```
 
+Available options (cf. `invoke --help test`):
+
+- `-c`, `--cov-lines`: display line numbers in coverage report
+- `-k [keyword]`, `--keyword [keyword]`: filter tests by keyword
+- `-v`, `--verbose`: enable verbose test output
+
 ### Benchmarks
 
 Benchmarks of different formats (`json`, `.npy`) and web server frameworks (`flask`, `tornado`) are run as part of the tests. Those benchmarks are based on [pytest-benchmark](https://pytest-benchmark.readthedocs.io/en/latest/).

tasks.py

@@ -31,7 +31,7 @@ def lint(c):
     mypy(c)
 
 
-@task
+@task(optional=["verbose", "keyword", "cov-lines"])
 def test(c, verbose=False, keyword="", cov_lines=False):
     """Test without benchmark"""
     c.run(