docs: describe how to run tests including NIST

README.md

@@ -35,6 +35,19 @@ statrs = "*" # replace * by the latest version of the crate.
 
 For examples, view [the docs](https://docs.rs/statrs/*/statrs/).
 
+### Running tests
+
+If you'd like to run all suggested tests, you'll need to download some data from
+NIST, we have a script for this and formatting the data in the `tests/` folder.
+
+```sh
+cargo test
+./tests/gather_nist_data.sh && cargo test -- --include-ignored nist_
+```
+
+If you'd like to modify where the data is downloaded, you can use the environment variable,
+`STATRS_NIST_DATA_DIR` for running the script and the tests.
+
 ## Contributing
 
 Thanks for your help to improve the project!

tests/nist_tests.rs

@@ -1,3 +1,20 @@
+//! This test relies on data that is reusable but not distributable by statrs as
+//! such, the data will need to be downloaded from the relevant NIST StRD dataset
+//! the parsing for testing assumes data to be of form,
+//! ```text
+//!     sample mean       : <possibly signed float for mean>
+//!     sample std_dev    : <possibly signed float for standard deviation>
+//!     sample correlation: <possibly signed float for correlation coefficient>
+//!     [zero or more blank lines]
+//!     data0
+//!     data1
+//!     data2
+//!     ...
+//! ```
+//! This test can be run on it's own from the shell from this folder as
+//! ```sh
+//!     ./gather_nist_data.sh && cargo test -- --ignored nist_
+//! ```
 use anyhow::Result;
 use approx::assert_relative_eq;
 use statrs::statistics::Statistics;