Add instructions and test for running against pytest.

README.md

@@ -12,10 +12,13 @@ Insure the following dependencies are in place:
     * Install using `rustup toolchain install nightly`
     * Set default toolchain `rustup default nightly`
 * Python 3 Development headers (python3-dev in Ubuntu)
+* pipenv `pip install --user pipenv`
 
 ## Running the Python example
 
 1. Build the rust crate first: `cargo build`
+1. Create the Python package with: `pyo3 develop`
+1. Run the tests: `pytest test.py`
 
 ## Documentation
 

test.py

@@ -1,2 +1,5 @@
 import unit_converter
 
+
+def test_using_unit_converter():
+    assert unit_converter.convert_celsius_to_fahrenheit(25.0) == 77.0