Add unit on testing

environment.yml

@@ -16,6 +16,7 @@
    - xarray
    - pip
    - ffmpeg
+   - pytest
    - pip:
      - python-awips
      - mpldatacursor

presentations/Testing/Testing.md

@@ -0,0 +1,52 @@
+Testing
+=======
+
+What is Software Testing?
+-------------------------
+- Testing is a way to make sure that software keeps working like you expect
+- You write code that runs other code and validates the results
+
+Types of Tests
+--------------
+- Unit tests
+  - Tests of individual units of code (functions, classes).
+  - Test wide array of inputs and cases try to exhaustively capture cases
+- Regression tests
+  - Test that nothing has broken after making changes
+- Integration tests
+  - Test that different pieces of code work together properly
+- Acceptance tests
+  - Test that code meets certain sets of external requirements
+
+- None of that matters to us as scientists
+
+Testing Strategies
+------------------
+- The right kind of test for your code: the kind you're willing to write
+- Requirements:
+  - Automated: computer can evaluate whether the test passes
+  - Consistent: no spurious failures
+  - Self-contained: no external resources, the test completely controls everything
+- At the very least, when you write code, you run it and verify the results
+  - Why not turn this into an automated test
+  - Doesn't prove correct
+  - Verifies that results you thought were sufficient haven't changed
+- For some code, can use e.g. values from source reference
+- In an ideal world, you write several tests spanning:
+  - input types (e.g. arrays, scalars)
+  - input domains
+  - edge cases
+
+Interactive:
+  - Add tests for `temperature.py` to `tests/test_temperature.py`
+    - values
+    - round trip
+  - How do we run tests: `pytest
+
+Exercise:
+  - Add calculations for mean and median to `stats.py`
+  - Add tests to make sure everything is working fine
+  - Make sure it works for both even- and odd-sized arrays
+
+Exercise:
+  - Use tests to find the bugs in the `moving_average` function

presentations/Testing/stats.py

@@ -0,0 +1,13 @@
+import numpy as np
+
+def median():
+    pass
+
+def mean():
+    pass
+
+def moving_average(vals, n):
+    out = []
+    for i in range(len(val) - n - 1):
+        out[i] = vals[i:i + n].mean()
+    return np.arry(vals)

presentations/Testing/temperature.py

@@ -0,0 +1,8 @@
+def to_kelvin(celsius):
+    return celsius + 273.15
+
+def to_celsius(fahrenheit):
+    return (fahrenheit - 32) / 1.8
+
+def to_fahrenheit(celsius):
+    return 1.8 * celsius + 32

presentations/Testing/tests/test_stats.py

@@ -0,0 +1,3 @@
+#
+# ADD TESTS HERE
+#

presentations/Testing/tests/test_temperature.py

@@ -0,0 +1,3 @@
+#
+# ADD TESTS HERE
+#