Slightly simplify examples

docs/tutorial/features/books.feature

@@ -6,7 +6,7 @@ Scenario: The catalog can be searched by author name.
     | Author          | Title                       |
     | Stephen King    | The Shining                 |
     | James Baldwin   | If Beale Street Could Talk  |
-    When a name search is performed for "Stephen"
+    When a name search is performed for Stephen
     Then only these books will be returned
     | Author          | Title                       |
     | Stephen King    | The Shining                 |

docs/tutorial/src/catalog.py

@@ -1,24 +1,27 @@
 """This files represents simple `Application under test`"""
-from typing import List
+from dataclasses import dataclass, field
+from typing import Iterable, List
 
-from attr import Factory, attrib, attrs
 
-
-@attrs
+@dataclass  # Easy way to not write redundant __init__ https://docs.python.org/3/library/dataclasses.html
 class Book:
-    author = attrib(type=str)
-    title = attrib(type=str)
+    author: str
+    title: str
 
 
-@attrs
+@dataclass
 class Catalog:
-    storage = attrib(default=Factory(list))
+    storage: List[Book] = field(default_factory=list)
 
-    def add_books_to_catalog(self, books: List[Book]):
+    def add_books_to_catalog(self, books: Iterable[Book]):
         self.storage.extend(books)
 
     def search_by_author(self, term: str):
-        return filter(lambda book: term in book.author, self.storage)
+        for book in self.storage:
+            if term in book.author:
+                yield book
 
     def search_by_title(self, term: str):
-        return filter(lambda book: term in book.title, self.storage)
+        for book in self.storage:
+            if term in book.title:
+                yield book

docs/tutorial/tests/steps/library_steps.py

@@ -1,5 +1,5 @@
 import re
-from typing import Literal
+from typing import List, Literal
 
 from src.catalog import Book, Catalog
 
@@ -8,13 +8,19 @@
 
 
 def get_books_from_data_table(data_table: DataTable):
-    # Gherkin data-tables have no title row by default, but we could use if we want.
-    step_data_table_titles = [cell.value for cell in data_table.rows[0].cells]
+    # Gherkin data-tables have no title row by default, but we could define them if we want.
+    title_row, *book_rows = data_table.rows
+
+    step_data_table_titles = []
+    for cell in title_row.cells:
+        step_data_table_titles.append(cell.value)
+
     assert step_data_table_titles == ["Author", "Title"]
 
-    author_and_title_list = [[cell.value for cell in row.cells] for row in data_table.rows[1:]]
+    books = []
+    for row in book_rows:
+        books.append(Book(row.cells[0].value, row.cells[1].value))
 
-    books = [Book(author, title) for author, title in author_and_title_list]
     return books
 
 
@@ -25,48 +31,55 @@ def get_books_from_data_table(data_table: DataTable):
     target_fixture="catalog",
 )
 def these_books_in_the_catalog(
-    # `step` fixture is injected by pytest DI mechanism into scope of step by default
+    # `step` fixture is injected by pytest dependency injection mechanism into scope of step by default;
+    # So it could be used without extra effort
     step: Step,
 ):
-    catalog = Catalog()
-
     books = get_books_from_data_table(step.data_table)
+
+    catalog = Catalog()
     catalog.add_books_to_catalog(books)
+
     yield catalog
 
 
 @when(
     # Step definitions could have parameters. Here could be raw stings, cucumber expressions or regular expressions
-    re.compile('a (?P<search_type>name|title) search is performed for "(?P<search_term>.+)"'),
+    re.compile("a (?P<search_type>name|title) search is performed for (?P<search_term>.+)"),
     target_fixture="search_results",
 )
 def a_search_type_is_performed_for_search_term(
-    # `search_results` is a usual pytest fixture defined somewhere else and injected by pytest DI mechanism.
+    # `search_results` is a usual pytest fixture defined somewhere else (at conftest.py, plugin or module) and injected by pytest dependency injection mechanism.
     # In this case it will be provided by conftest.py
-    search_results,
+    search_results: List[Book],
     # `search_type` and `search_term` are parameters of this step and are injected by step definition
     search_type: Literal["name", "title"],
     search_term: str,
     # `catalog` is a fixture injected by another step
     catalog: Catalog,
 ):
     if search_type == "title":
-        search_results.extend(catalog.search_by_title(search_term))
+        search = catalog.search_by_title
     elif search_type == "name":
-        search_results.extend(catalog.search_by_author(search_term))
+        search = catalog.search_by_author
     else:
         assert False, "Unknown"
 
+    found_books = search(search_term)
+    search_results.extend(found_books)
     yield search_results
 
 
 @then("only these books will be returned")
 def only_these_books_will_be_returned(
-    # fixtures persist during step execution, so usual context is not required,
+    # Fixtures persist during step execution, so usual `context` common for behave users is not required,
     # so if you define fixture dependencies debugging becomes much easier.
-    search_results,
+    search_results: List[Book],
     step: Step,
     catalog: Catalog,
 ):
     expected_books = get_books_from_data_table(step.data_table)
-    assert all([book in catalog.storage for book in expected_books])
+
+    for book in search_results:
+        if book not in expected_books:
+            assert False, f"Book ${book} is not expected"