Create count_occurrences task

Author: danylott

README.md

@@ -1,4 +1,4 @@
-# Python boilerplate for GitHub tasks
+# Count Occurrences
 
 - Read [the guideline](https://github.com/mate-academy/py-task-guideline/blob/main/README.md) before start
 - Implement the task described [here](app/main.py)

app/main.py

@@ -1,3 +1,17 @@
-# TODO: add initial code
-def hello_world():
-    return "Hello, world!"
+def count_occurrences(phrase: str, letter: str) -> int:
+    """
+    Implement count_occurrences function:
+
+    It takes a phrase and a letter and calculates the number of times
+    the letter appears in the phrase. The function is case insensitive.
+
+    count_occurrences("letter", "t") == 2
+    count_occurrences("abc", "a") == 1
+    count_occurrences("abc", "d") == 0
+    count_occurrences("ABC", "a") == 1
+
+    :param phrase: phrase to count in it
+    :param letter: letter to find occurrences of it
+    :return: count occurrences of letter in phrase
+    """
+    # write your code here

tests/test_main.py

@@ -1,6 +1,21 @@
-# TODO: add tests
-from app.main import hello_world
+import pytest
 
+from app.main import count_occurrences
 
-def test_hello_world():
-    assert hello_world() == "Hello, world!"
+
+@pytest.mark.parametrize(
+    "phrase,letter,count",
+    [
+        ("samsung", "a", 1),
+        ("samsung is gnusmas", "s", 5),
+        ("Samsung is gnusmas", "s", 5),
+        ("Abracadabra", "A", 5),
+        ("", "a", 0),
+        ("Samsung", "b", 0),
+    ]
+)
+def test_count_occurrences(phrase, letter, count):
+    assert count_occurrences(phrase, letter) == count, (
+        f"Function 'count_occurrences' should return {count}, "
+        f"when 'phrase'='{phrase}' and 'letter'='{letter}'"
+    )