Merge pull request #67 from josemoracard/jose14-ejercicio-46-init_and_str_magic_methods

añadido ejercicio 42.1-init_and_str_methods

Author: alesanchezr

exercises/042.1-init_and_str_methods/README.es.md

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+# `042.1` `__init__` and `__str__` methods
+
+Normalmente, al trabajar con clases, te encontrarás con métodos de este estilo `__<método>__`; estos son conocidos como "métodos mágicos". Existen varios de ellos, y cada uno desempeña una función específica. En esta ocasión, nos enfocaremos en aprender dos de los más fundamentales.
+
+El método mágico `__init__` es esencial para la inicialización de objetos dentro de una clase. Se ejecuta automáticamente cuando se crea una nueva instancia de la clase, permitiendo la asignación de valores iniciales a los atributos del objeto. 
+
+El método `__str__` se utiliza para proporcionar una representación de cadena legible de la instancia, permitiendo personalizar la salida cuando se imprime el objeto. Esto es especialmente útil para mejorar la legibilidad del código y facilitar la depuración, ya que define una versión amigable para humanos de la información contenida en el objeto.
+
+## 📎 Ejemplo:
+
+```py
+class Person:
+    def __init__(self, name, age, gender):
+        self.name = name
+        self.age = age
+        self.gender = gender
+
+    def __str__(self):
+        return f"{self.name}, {self.age} years old, {self.gender}"
+
+# Create an instance of the Person class
+person1 = Person("Juan", 25, "Male")
+
+# Print the information of the person using the __str__ method
+print(person1)  # Output: Juan, 25 years old, Male
+```
+
+## 📝 Instrucciones:
+
+1. Crea una clase llamada `Book` que tenga los métodos `__init__` y `__str__`.
+
+2. El método `__init__` debe inicializar los atributos `title`, `author` y `year`.
+
+3. El método `__str__` debe devolver una cadena que represente la información de una instancia del siguiente libro de esta manera:
+
+```py
+book1 = ("The Great Gatsby", "F. Scott Fitzgerald", 1925)
+
+print(book1)
+
+# Output:
+#
+# Book Title: The Great Gatsby
+# Author: F. Scott Fitzgerald
+# Year: 1925
+```
+
+## 💡 Pistas:
+
++ Utiliza el método `__init__` para inicializar los atributos de la instancia.
+
++ Utiliza el método `__str__` para proporcionar una representación de cadena legible de la instancia.
+
++ Para hacer saltos de línea dentro de un string puedes usar los siguientes caracteres `\n`.

exercises/042.1-init_and_str_methods/README.md

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+# `042.1` `__init__` and `__str__` methods
+
+Typically, when working with classes, you will encounter methods of the form `__<method>__`; these are known as "magic methods." There are a lot of them, each serving a specific purpose. This time, we will focus on learning two of the most fundamental ones.
+
+The magic method `__init__` is essential for the initialization of objects within a class. It is automatically executed when a new instance of the class is created, allowing for the assignment of initial values to the object's attributes.
+
+The `__str__` method is used to provide a readable string representation of the instance, allowing customization of the output when the object is printed. This is especially useful for improving code readability and facilitating debugging, as it defines a human-friendly version of the information contained in the object.
+
+## 📎 Example:
+
+```py
+class Person:
+    def __init__(self, name, age, gender):
+        self.name = name
+        self.age = age
+        self.gender = gender
+
+    def __str__(self):
+        return f"{self.name}, {self.age} years old, {self.gender}"
+
+# Create an instance of the Person class
+person1 = Person("Juan", 25, "Male")
+
+# Print the information of the person using the __str__ method
+print(person1)  # Output: Juan, 25 years old, Male
+```
+
+## 📝 Instructions:
+
+1. Create a class called `Book` that has the `__init__` and `__str__` methods.
+
+2. The `__init__` method should initialize the `title`, `author`, and `year` attributes.
+
+3. The `__str__` method should return a string representing the information of an instance of the following book in this manner:
+
+```py
+book1 = ("The Great Gatsby", "F. Scott Fitzgerald", 1925)
+
+print(book1)
+
+# Output:
+#
+# Book Title: The Great Gatsby
+# Author: F. Scott Fitzgerald
+# Year: 1925
+```
+
+## 💡 Hints:
+
++ Use the `__init__` method to initialize the instance's attributes.
+
++ Use the `__str__` method to provide a readable string representation of the instance.
+
++ To create line breaks within a string, you can use the `\n` characters.

exercises/042.1-init_and_str_methods/app.py

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+# Your code here
+

exercises/042.1-init_and_str_methods/solution.hide.py

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+# Your code here
+
+class Book:
+    def __init__(self, title, author, year):
+        self.title = title
+        self.author = author
+        self.year = year
+
+    def __str__(self):
+        return f"Book Title: {self.title}\nAuthor: {self.author}\nYear: {self.year}"
+
+book1 = Book("The Great Gatsby", "F. Scott Fitzgerald", 1925)
+
+print(book1)

exercises/042.1-init_and_str_methods/test.py

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+import pytest
+from app import Book
+
+@pytest.mark.it("The Book class exists")
+def test_book_class_exists():
+    try:
+        assert Book
+    except AttributeError:
+        raise AttributeError("The class 'Book' should exist in app.py")
+
+@pytest.mark.it("The Book class has the __init__ method")
+def test_book_has_init_method():
+    assert hasattr(Book, "__init__")
+
+@pytest.mark.it("The __init__ method initializes the title, author, and year attributes")
+def test_init_method_initializes_attributes():
+    book = Book("The Great Gatsby", "F. Scott Fitzgerald", 1925)
+    assert hasattr(book, "title")
+    assert hasattr(book, "author")
+    assert hasattr(book, "year")
+
+@pytest.mark.it("The Book class has the __str__ method")
+def test_book_has_str_method():
+    assert hasattr(Book, "__str__")
+
+@pytest.mark.it("The __str__ method returns the expected string")
+def test_str_method_returns_expected_string(capsys):
+    book = Book("The Great Gatsby", "F. Scott Fitzgerald", 1925)
+    print(book)
+    captured = capsys.readouterr()
+    expected_output = "Book Title: The Great Gatsby\nAuthor: F. Scott Fitzgerald\nYear: 1925\n"
+    assert captured.out == expected_output
+