Add Micro Blog Exercise (#649)

Author: tomasnorre

config.json

@@ -1148,6 +1148,14 @@
         "prerequisites": [],
         "difficulty": 5
       },
+      {
+        "slug": "micro-blog",
+        "name": "Micro Blog",
+        "uuid": "203ba680-cdbd-494d-a1b6-af426bc84e59",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 1
+      },
       {
         "slug": "yacht",
         "name": "Yacht",

exercises/practice/micro-blog/.docs/instructions.md

@@ -0,0 +1,37 @@
+# Instructions
+
+You have identified a gap in the social media market for very very short posts.
+Now that Twitter allows 280 character posts, people wanting quick social media updates aren't being served.
+You decide to create your own social media network.
+
+To make your product noteworthy, you make it extreme and only allow posts of 5 or less characters.
+Any posts of more than 5 characters should be truncated to 5.
+
+To allow your users to express themselves fully, you allow Emoji and other Unicode.
+
+The task is to truncate input strings to 5 characters.
+
+## Text Encodings
+
+Text stored digitally has to be converted to a series of bytes.
+There are 3 ways to map characters to bytes in common use.
+
+- **ASCII** can encode English language characters.
+  All characters are precisely 1 byte long.
+- **UTF-8** is a Unicode text encoding.
+  Characters take between 1 and 4 bytes.
+- **UTF-16** is a Unicode text encoding.
+  Characters are either 2 or 4 bytes long.
+
+UTF-8 and UTF-16 are both Unicode encodings which means they're capable of representing a massive range of characters including:
+
+- Text in most of the world's languages and scripts
+- Historic text
+- Emoji
+
+UTF-8 and UTF-16 are both variable length encodings, which means that different characters take up different amounts of space.
+
+Consider the letter 'a' and the emoji '😛'.
+In UTF-16 the letter takes 2 bytes but the emoji takes 4 bytes.
+
+The trick to this exercise is to use APIs designed around Unicode characters (codepoints) instead of Unicode codeunits.

exercises/practice/micro-blog/.meta/config.json

@@ -0,0 +1,17 @@
+{
+  "authors": [
+    "tomasnorre"
+  ],
+  "files": {
+    "solution": [
+      "MicroBlog.php"
+    ],
+    "test": [
+      "MicroBlogTest.php"
+    ],
+    "example": [
+      ".meta/example.php"
+    ]
+  },
+  "blurb": "Given an input string, truncate it to 5 characters."
+}

exercises/practice/micro-blog/.meta/example.php

@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+class MicroBlog
+{
+    public function truncate(string $text): string
+    {
+        return mb_substr($text, 0, 5);
+    }
+}

exercises/practice/micro-blog/.meta/tests.toml

@@ -0,0 +1,46 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[b927b57f-7c98-42fd-8f33-fae091dc1efc]
+description = "English language short"
+
+[a3fcdc5b-0ed4-4f49-80f5-b1a293eac2a0]
+description = "English language long"
+
+[01910864-8e15-4007-9c7c-ac956c686e60]
+description = "German language short (broth)"
+
+[f263e488-aefb-478f-a671-b6ba99722543]
+description = "German language long (bear carpet → beards)"
+
+[0916e8f1-41d7-4402-a110-b08aa000342c]
+description = "Bulgarian language short (good)"
+
+[bed6b89c-03df-4154-98e6-a61a74f61b7d]
+description = "Greek language short (health)"
+
+[485a6a70-2edb-424d-b999-5529dbc8e002]
+description = "Maths short"
+
+[8b4b7b51-8f48-4fbe-964e-6e4e6438be28]
+description = "Maths long"
+
+[71f4a192-0566-4402-a512-fe12878be523]
+description = "English and emoji short"
+
+[6f0f71f3-9806-4759-a844-fa182f7bc203]
+description = "Emoji short"
+
+[ce71fb92-5214-46d0-a7f8-d5ba56b4cc6e]
+description = "Emoji long"
+
+[5dee98d2-d56e-468a-a1f2-121c3f7c5a0b]
+description = "Royal Flush?"

exercises/practice/micro-blog/MicroBlog.php

@@ -0,0 +1,33 @@
+<?php
+
+/*
+ * By adding type hints and enabling strict type checking, code can become
+ * easier to read, self-documenting and reduce the number of potential bugs.
+ * By default, type declarations are non-strict, which means they will attempt
+ * to change the original type to match the type specified by the
+ * type-declaration.
+ *
+ * In other words, if you pass a string to a function requiring a float,
+ * it will attempt to convert the string value to a float.
+ *
+ * To enable strict mode, a single declare directive must be placed at the top
+ * of the file.
+ * This means that the strictness of typing is configured on a per-file basis.
+ * This directive not only affects the type declarations of parameters, but also
+ * a function's return type.
+ *
+ * For more info review the Concept on strict type checking in the PHP track
+ * <link>.
+ *
+ * To disable strict typing, comment out the directive below.
+ */
+
+declare(strict_types=1);
+
+class MicroBlog
+{
+    public function truncate(string $text): string
+    {
+        throw new \BadMethodCallException(sprintf('Implement the %s method', __FUNCTION__));
+    }
+}

exercises/practice/micro-blog/MicroBlogTest.php

@@ -0,0 +1,114 @@
+<?php
+
+declare(strict_types=1);
+
+class MicroBlogTest extends PHPUnit\Framework\TestCase
+{
+    private MicroBlog $microBlog;
+
+    public static function setUpBeforeClass(): void
+    {
+        require_once 'MicroBlog.php';
+    }
+
+    protected function setUp(): void
+    {
+        $this->microBlog = new MicroBlog();
+    }
+
+    /**
+     * uuid: b927b57f-7c98-42fd-8f33-fae091dc1efc
+     */
+    public function testEnglishLanguageShort(): void
+    {
+        $this->assertEquals('Hi', $this->microBlog->truncate('Hi'));
+    }
+
+    /**
+     * uuid: a3fcdc5b-0ed4-4f49-80f5-b1a293eac2a0
+     */
+    public function testEnglishLanguageLong(): void
+    {
+        $this->assertEquals('Hello', $this->microBlog->truncate('Hello there'));
+    }
+
+    /**
+     * uuid: 01910864-8e15-4007-9c7c-ac956c686e60
+     */
+    public function testGermanLanguageShortBroth(): void
+    {
+        $this->assertEquals('brühe', $this->microBlog->truncate('brühe'));
+    }
+
+    /**
+     * uuid: f263e488-aefb-478f-a671-b6ba99722543
+     */
+    public function testGermanLanguageLongBearCarpetToBeards(): void
+    {
+        $this->assertEquals('Bärte', $this->microBlog->truncate('Bärteppich'));
+    }
+
+    /**
+     * uuid: 0916e8f1-41d7-4402-a110-b08aa000342c
+     */
+    public function testBulgarianLanguageShortGood(): void
+    {
+        $this->assertEquals('Добър', $this->microBlog->truncate('Добър'));
+    }
+
+    /**
+     * uuid: bed6b89c-03df-4154-98e6-a61a74f61b7d
+     */
+    public function testGreekLanguageShortHealth(): void
+    {
+        $this->assertEquals('υγειά', $this->microBlog->truncate('υγειά'));
+    }
+
+    /**
+     * uuid: 485a6a70-2edb-424d-b999-5529dbc8e002
+     */
+    public function testMathShort(): void
+    {
+        $this->assertEquals('a=πr²', $this->microBlog->truncate('a=πr²'));
+    }
+
+    /**
+     * uuid: 8b4b7b51-8f48-4fbe-964e-6e4e6438be28
+     */
+    public function testMathLong(): void
+    {
+        $this->assertEquals('∅⊊ℕ⊊ℤ', $this->microBlog->truncate('∅⊊ℕ⊊ℤ⊊ℚ⊊ℝ⊊ℂ'));
+    }
+
+    /**
+     * uuid: 71f4a192-0566-4402-a512-fe12878be523
+     */
+    public function testEnglishAndEmojiShort(): void
+    {
+        $this->assertEquals('Fly 🛫', $this->microBlog->truncate('Fly 🛫'));
+    }
+
+    /**
+     * uuid: 6f0f71f3-9806-4759-a844-fa182f7bc203
+     */
+    public function testEmojiShort(): void
+    {
+        $this->assertEquals('💇', $this->microBlog->truncate('💇'));
+    }
+
+    /**
+     * uuid: ce71fb92-5214-46d0-a7f8-d5ba56b4cc6e
+     */
+    public function testEmojiLong(): void
+    {
+        $this->assertEquals('❄🌡🤧🤒🏥', $this->microBlog->truncate('❄🌡🤧🤒🏥🕰😀'));
+    }
+
+    /**
+     * uuid: 5dee98d2-d56e-468a-a1f2-121c3f7c5a0b
+     */
+    public function testRoyalFlush(): void
+    {
+        $this->assertEquals('🃎🂸🃅🃋🃍', $this->microBlog->truncate('🃎🂸🃅🃋🃍🃁🃊'));
+    }
+}