1 The code, with its test

just setup

Code and its test arrive together, so the test checks the code from the first day. Read tests/test_count.py, then count.

uv run python -m unittest discover -s tests -v
git log --oneline --graph --all | head -12

Both tests pass. The graph shows the branch parts, which leaves main where the project begins.

Ask: is it easier to read a test before the code, or after?

What changed

.gitignore: New, 10 lines. The file.
.python-version: New, 1 line. The file.
README.md: New, 3 lines. The file.
justfile: adds recipe default, recipe run, recipe setup, recipe test. New, 15 lines. The file.
pyproject.toml: New, 14 lines. The file.
src/tally/__init__.py: count, which ignores case from the first day, and the command. New, 16 lines. The file.
- look at for word in text.lower().split():
src/tally/__main__.py: New, 3 lines. The file.
tests/test_count.py: a test of counting, and a test of case. New, 11 lines. The file.
- look at self.assertEqual(count("A a"), {"a": 2})
uv.lock: New, 8 lines. The file.

The diff of .gitignore

@@ -0,0 +1,10 @@
+# Python-generated files
+__pycache__/
+*.py[oc]
+build/
+dist/
+wheels/
+*.egg-info
+
+# Virtual environments
+.venv

The diff of .python-version

@@ -0,0 +1 @@
+3.12

The diff of README.md

@@ -0,0 +1,3 @@
+# tally
+
+Count the words in a text.

The diff of justfile

@@ -0,0 +1,15 @@
+# The recipes of tally. Each one runs through uv, in the project's own environment.
+default:
+    @just --list
+
+# Make the environment of this step: the first command of every step
+setup:
+    uv sync
+
+# Count the words of a file
+run file:
+    uv run tally {{ file }}
+
+# Run the tests
+test:
+    uv run python -m unittest discover -s tests -q

The diff of pyproject.toml

@@ -0,0 +1,14 @@
+[project]
+name = "tally"
+version = "0.1.0"
+description = "Count the words in a text"
+readme = "README.md"
+requires-python = ">=3.12"
+dependencies = []
+
+[project.scripts]
+tally = "tally:main"
+
+[build-system]
+requires = ["uv_build>=0.12.13,<0.13.0"]
+build-backend = "uv_build"

The diff of src/tally/__init__.py

@@ -0,0 +1,16 @@
+"""tally: count the words in a text."""
+
+import sys
+
+
+def count(text):
+    counts = {}
+    for word in text.lower().split():
+        counts[word] = counts.get(word, 0) + 1
+    return counts
+
+
+def main() -> None:
+    text = open(sys.argv[1]).read() if len(sys.argv) > 1 else sys.stdin.read()
+    for word, n in sorted(count(text).items()):
+        print(n, word)

The diff of src/tally/__main__.py

@@ -0,0 +1,3 @@
+from tally import main
+
+main()

The diff of tests/test_count.py

@@ -0,0 +1,11 @@
+import unittest
+
+from tally import count
+
+
+class Count(unittest.TestCase):
+    def test_words(self):
+        self.assertEqual(count("a b a"), {"a": 2, "b": 1})
+
+    def test_case(self):
+        self.assertEqual(count("A a"), {"a": 2})

The code.