Merge pull request #98 from jetbrains-academy/sofia/second_else_with_loops_task

Added another task for else with loops to cover more concepts

Author: Geravant

Loops/Else with loops 2/__init__.py

@@ -0,0 +1,14 @@
+type: edu
+files:
+- name: task.py
+  visible: true
+  placeholders:
+  - offset: 35
+    length: 184
+    placeholder_text: pass
+- name: tests/test_task.py
+  visible: false
+- name: __init__.py
+  visible: false
+- name: tests/__init__.py
+  visible: false

Loops/Else with loops 2/task-info.yaml

@@ -0,0 +1,38 @@
+## Else with loops 2
+
+This type of `else` is useful only if there is an `if` condition present inside the loop, which somehow depends on the loop variable.
+Let's look once again at the example from the previous task:
+
+```python
+for n in range(2, 10):
+    for x in range(2, n):
+        if n % x == 0:
+            print(n, 'equals', x, '*', n//x)
+            break
+    else:
+        # loop fell through without finding a factor
+        print(n, 'is a prime number')
+```
+
+The `else` statement will only be executed if `n` is a prime number, i.e. the `if` statement has not been executed for any iteration of the inner
+`for` loop. 
+
+### Task
+
+Inside the [function](course://Functions/Definition) `contains_even_number()`, write a `for` loop that would iterate over a list `lst` and, if an even element is found,
+print `f"List {lst} contains an even number."` and exit the loop, if no such element is found, print `f"List {lst} does not contain an even number."`. 
+
+<div class="hint">
+
+You can use `if i % 2 == 0:` to test if a given number is even.
+</div>
+
+<div class="hint">
+
+Use the `break` statement to exit the loop if an even number is found.
+</div>
+
+<div class="hint">
+
+Use an `else` clause to print `f"List {lst} does not contain an even number."`.
+</div>

Loops/Else with loops 2/task.md

@@ -0,0 +1,11 @@
+def contains_even_number(lst):
+    for i in lst:
+        if i % 2 == 0:
+            print(f"List {lst} contains an even number.")
+            break
+    else:
+        print(f"List {lst} does not contain an even number.")
+
+
+contains_even_number([1, 9, 8])
+contains_even_number([1, 3, 5])

Loops/Else with loops 2/task.py

@@ -0,0 +1,42 @@
+import unittest
+import contextlib
+import io
+
+
+from task import contains_even_number
+
+
+class TestCase(unittest.TestCase):
+    def test_even(self):
+        f = io.StringIO()
+
+        with contextlib.redirect_stdout(f):
+            contains_even_number([1, 9, 37, 4])
+        output = f.getvalue().split('\n')
+        self.assertEqual(['List [1, 9, 37, 4] contains an even number.', ''], output, msg="Incorrect result for a "
+                                                                                          "list with an even number.")
+
+    def test_even_several_times(self):
+        f = io.StringIO()
+
+        with contextlib.redirect_stdout(f):
+            contains_even_number([1, 9, 8, 8, 8])
+        output = f.getvalue().split('\n')
+        self.assertEqual(['List [1, 9, 8, 8, 8] contains an even number.', ''], output, msg="For a list with any "
+                                                                                            "number of even values "
+                                                                                            "the phrase 'List {lst} "
+                                                                                            "contains an even number' "
+                                                                                            "should only be printed "
+                                                                                            "once. You might have "
+                                                                                            "missed a break "
+                                                                                            "statement.")
+
+    def test_odd(self):
+        f = io.StringIO()
+
+        with contextlib.redirect_stdout(f):
+            contains_even_number([1, 9, 37, 5])
+        output = f.getvalue().split('\n')
+        self.assertEqual(['List [1, 9, 37, 5] does not contain an even number.', ''], output, msg="Incorrect result "
+                                                                                                  "for a list without"
+                                                                                                  " an even number.")

Loops/Else with loops 2/tests/__init__.py

@@ -8,4 +8,5 @@ content:
 - Break keyword
 - Fix infinite execution
 - Else with loops
+- Else with loops 2
 - Continue keyword