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Implement micro-blog exercise. (exercism#1805)
* Implement micro-blog exercise. * Fix implementation of reference solution. Needs to use appendCodePoint rather than append. * Use an instance method instead of a static class method. * Clean up the micro-blog exercise to fit latest changes.
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β€Žconfig.json

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"strings"
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]
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},
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{
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"slug": "micro-blog",
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"uuid": "8295ae71-5c0e-49d0-bbe9-9b43a85bf2dd",
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"core": false,
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"unlocked_by": "two-fer",
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"difficulty": 3,
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"topics": [
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"strings"
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]
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},
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{
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"slug": "yacht",
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"uuid": "0cb45688-9598-49aa-accc-ed48c5d6962d",

β€Žexercises/micro-blog/.meta/src/reference/java/MicroBlog.java

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class MicroBlog {
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public String truncate(String input) {
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return input.codePoints()
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.limit(5)
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.collect(
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StringBuilder::new,
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StringBuilder::appendCodePoint,
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StringBuilder::append)
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.toString();
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}
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}

β€Žexercises/micro-blog/.meta/version

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1.0.0

β€Žexercises/micro-blog/README.md

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# Micro Blog
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You have identified a gap in the social media market for very very short
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posts. Now that Twitter allows 280 character posts, people wanting quick
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social media updates aren't being served. You decide to create your own
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social media network.
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To make your product noteworthy, you make it extreme and only allow posts
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of 5 or less characters. Any posts of more than 5 characters should be
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truncated to 5.
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To allow your users to express themselves fully, you allow Emoji and
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other Unicode.
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The task is to truncate input strings to 5 characters.
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## Text Encodings
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Text stored digitally has to be converted to a series of bytes.
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There are 3 ways to map characters to bytes in common use.
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* **ASCII** can encode English language characters. All
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characters are precisely 1 byte long.
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* **UTF-8** is a Unicode text encoding. Characters take between 1
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and 4 bytes.
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* **UTF-16** is a Unicode text encoding. Characters are either 2 or
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4 bytes long.
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UTF-8 and UTF-16 are both Unicode encodings which means they're capable of
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representing a massive range of characters including:
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* Text in most of the world's languages and scripts
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* Historic text
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* Emoji
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UTF-8 and UTF-16 are both variable length encodings, which means that
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different characters take up different amounts of space.
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Consider the letter 'a' and the emoji 'πŸ˜›'. In UTF-16 the letter takes
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2 bytes but the emoji takes 4 bytes.
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The trick to this exercise is to use APIs designed around Unicode
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characters (codepoints) instead of Unicode codeunits.
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## Setup
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Go through the setup instructions for Java to install the necessary
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dependencies:
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[https://exercism.io/tracks/java/installation](https://exercism.io/tracks/java/installation)
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# Running the tests
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You can run all the tests for an exercise by entering the following in your
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terminal:
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```sh
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$ gradle test
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```
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In the test suites all tests but the first have been skipped.
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Once you get a test passing, you can enable the next one by removing the
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`@Ignore("Remove to run test")` annotation.
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## Submitting Incomplete Solutions
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It's possible to submit an incomplete solution so you can see how others have
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completed the exercise.

β€Žexercises/micro-blog/build.gradle

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apply plugin: "java"
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apply plugin: "eclipse"
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apply plugin: "idea"
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repositories {
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mavenCentral()
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}
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dependencies {
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testCompile "junit:junit:4.13"
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testImplementation "org.assertj:assertj-core:3.15.0"
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}
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test {
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testLogging {
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exceptionFormat = 'short'
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showStandardStreams = true
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events = ["passed", "failed", "skipped"]
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}
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}

β€Žexercises/micro-blog/src/main/java/MicroBlog.java

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class MicroBlog {
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public String truncate(String input) {
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throw new UnsupportedOperationException("Delete this statement and write your own implementation.");
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}
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}

β€Žexercises/micro-blog/src/test/java/MicroBlogTest.java

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import static org.junit.Assert.assertEquals;
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import org.junit.Ignore;
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import org.junit.Test;
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public class MicroBlogTest {
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private final MicroBlog microBlog = new MicroBlog();
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@Test
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public void englishLanguageShort() {
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String expected = "Hi";
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assertEquals(expected, microBlog.truncate("Hi"));
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}
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@Ignore("Remove to run test")
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@Test
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public void englishLanguageLong() {
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String expected = "Hello";
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assertEquals(expected, microBlog.truncate("Hello there"));
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}
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@Ignore("Remove to run test")
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@Test
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public void germanLanguageShort_broth() {
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String expected = "brΓΌhe";
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assertEquals(expected, microBlog.truncate("brΓΌhe"));
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}
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@Ignore("Remove to run test")
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@Test
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public void germanLanguageLong_bearCarpet_to_beards() {
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String expected = "BΓ€rte";
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assertEquals(expected, microBlog.truncate("BΓ€rteppich"));
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}
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@Ignore("Remove to run test")
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@Test
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public void bulgarianLanguageShort_good() {
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String expected = "Π”ΠΎΠ±ΡŠΡ€";
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assertEquals(expected, microBlog.truncate("Π”ΠΎΠ±ΡŠΡ€"));
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}
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@Ignore("Remove to run test")
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@Test
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public void greekLanguageShort_health() {
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String expected = "υγΡιά";
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assertEquals(expected, microBlog.truncate("υγΡιά"));
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}
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@Ignore("Remove to run test")
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@Test
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public void mathsShort() {
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String expected = "a=Ο€rΒ²";
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assertEquals(expected, microBlog.truncate("a=Ο€rΒ²"));
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}
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@Ignore("Remove to run test")
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@Test
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public void mathsLong() {
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String expected = "βˆ…βŠŠβ„•βŠŠβ„€";
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assertEquals(expected, microBlog.truncate("βˆ…βŠŠβ„•βŠŠβ„€βŠŠβ„šβŠŠβ„βŠŠβ„‚"));
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}
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@Ignore("Remove to run test")
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@Test
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public void englishAndEmojiShort() {
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String expected = "Fly πŸ›«";
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assertEquals(expected, microBlog.truncate("Fly πŸ›«"));
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}
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@Ignore("Remove to run test")
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@Test
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public void emojiShort() {
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String expected = "πŸ’‡";
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assertEquals(expected, microBlog.truncate("πŸ’‡"));
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}
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@Ignore("Remove to run test")
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@Test
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public void emojiLong() {
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String expected = "β„πŸŒ‘πŸ€§πŸ€’πŸ₯";
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assertEquals(expected, microBlog.truncate("β„πŸŒ‘πŸ€§πŸ€’πŸ₯πŸ•°πŸ˜€"));
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}
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@Ignore("Remove to run test")
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@Test
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public void royalFlush() {
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String expected = "πŸƒŽπŸ‚ΈπŸƒ…πŸƒ‹πŸƒ";
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assertEquals(expected, microBlog.truncate("πŸƒŽπŸ‚ΈπŸƒ…πŸƒ‹πŸƒπŸƒπŸƒŠ"));
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}
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}

β€Žexercises/settings.gradle

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include 'matching-brackets'
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include 'matrix'
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include 'meetup'
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include 'micro-blog'
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include 'minesweeper'
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include 'nth-prime'
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include 'nucleotide-count'

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