2.1 to 2.3 Three tests of counting

2.1 A test of counting

Nothing checks yet that count gives the right counts. A test of unittest, the test library of Python, calls count on a short text and compares the result with the dictionary that it expects. The tests go in a new folder, tests.

The first file of tests, tests/test_count.py, has two tests. test_words counts a b a. test_case counts A a, and expects the one word a, twice. The code cannot do this yet.

A patch to tests/test_count.py.

In the change of tests/test_count.py, look at test_case. It is the test that fails below.

uv run python -m unittest discover -s tests -q

One test fails. test_case expects {'a': 2}, and gets {'A': 1, 'a': 1}. The failure is a question that the code has not answered yet.

The first two tests are the pattern for the third. A test gives count a text, and compares what count gives back with the counts that it must give.

@@ -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})

2.2 A test of an empty text

An empty file is a text with no words. count must give an empty dictionary for it, and not fail. A test in a file of its own, tests/test_empty.py, says so, and keeps it true after later changes.

A patch to tests/test_empty.py.

The new file tests/test_empty.py holds one test, test_empty. It gives count the empty text "", and expects the empty dictionary {}.

uv run python -m unittest discover -s tests -q

The new test passes at once, because split() finds no words in an empty text. test_case still fails.

@@ -0,0 +1,8 @@
+import unittest
+
+from tally import count
+
+
+class Empty(unittest.TestCase):
+    def test_empty(self):
+        self.assertEqual(count(""), {})

2.3 Case does not matter

test_case fails, because count counts A and a as two words. When count puts the text in lower case before it splits it, every word is counted in lower case. One word in the loop of count, lower(), does it.

A patch to src/tally/__init__.py.

In count, in src/tally/__init__.py, the loop now splits text.lower(), and not text. So A and a are the same word.

uv run python -m unittest discover -s tests -q
echo "The the" | uv run tally

All three tests pass, and the command prints 2 the for "The the".

Three tests now say what count does. It counts words, it gives nothing for an empty text, and it ignores case.

@@ -5,7 +5,7 @@ import sys
 
 def count(text):
     counts = {}
-    for word in text.split():
+    for word in text.lower().split():
         counts[word] = counts.get(word, 0) + 1
     return counts