Format admonitions (#2327)

Format admonitions to adhere to Exercism standards (four tildes)

Author: ErikSchierboom

.github/workflows/action-format.yml

@@ -90,7 +90,7 @@ jobs:
         run: yarn format-json && ruby bin/format-array.rb
 
       - name: Format Markdown files
-        run: yarn format-md
+        run: yarn format-md && ruby bin/format-admonition-fences.rb
 
       - name: 'Commit formatted code'
         run: |

.github/workflows/ci.yml

@@ -134,9 +134,9 @@ jobs:
 
       - name: Verify that markdown files are formatted correctly
         run: |
-          yarn format-md
+          yarn format-md && ruby bin/format-admonition-fences.rb
           if ! git diff --quiet --exit-code; then
-            echo "please format the files with prettier, or apply the following changes:"
+            echo "please format the files using 'yarn format-md && ruby bin/format-admonition-fences.rb', or apply the following changes:"
             git diff
             exit 1
           fi

bin/format-admonition-fences.rb

@@ -0,0 +1,10 @@
+#!/usr/bin/env ruby
+
+BACKTICK_MATCH_REGEX = /(?<fence>[`~]{3,})(?<type>exercism\/[a-z]+)(?<admonition>.*?)(?<end>\k<fence>)/m.freeze
+TILDE_REPLACE = '~~~~\k<type>\k<admonition>~~~~'.freeze
+
+Dir.glob('exercises/**/*.md') do |filepath|
+  contents = File.read(filepath)
+  contents.gsub!(BACKTICK_MATCH_REGEX, TILDE_REPLACE)
+  File.write(filepath, contents)
+end

exercises/binary-search/instructions.md

@@ -5,9 +5,9 @@ Your task is to implement a binary search algorithm.
 A binary search algorithm finds an item in a list by repeatedly splitting it in half, only keeping the half which contains the item we're looking for.
 It allows us to quickly narrow down the possible locations of our item until we find it, or until we've eliminated all possible locations.
 
-```exercism/caution
+~~~~exercism/caution
 Binary search only works when a list has been sorted.
-```
+~~~~
 
 The algorithm looks like this:
 

exercises/etl/instructions.md

@@ -22,6 +22,6 @@ This needs to be changed to store each individual letter with its score in a one
 
 As part of this change, the team has also decided to change the letters to be lower-case rather than upper-case.
 
-```exercism/note
+~~~~exercism/note
 If you want to look at how the data was previously structured and how it needs to change, take a look at the examples in the test suite.
-```
+~~~~

exercises/gigasecond/introduction.md

@@ -13,12 +13,12 @@ Then we can use metric system prefixes for writing large numbers of seconds in m
 - Perhaps you and your family would travel to somewhere exotic for two megaseconds (that's two million seconds).
 - And if you and your spouse were married for _a thousand million_ seconds, you would celebrate your one gigasecond anniversary.
 
-```exercism/note
+~~~~exercism/note
 If we ever colonize Mars or some other planet, measuring time is going to get even messier.
 If someone says "year" do they mean a year on Earth or a year on Mars?
 
 The idea for this exercise came from the science fiction novel ["A Deepness in the Sky"][vinge-novel] by author Vernor Vinge.
 In it the author uses the metric system as the basis for time measurements.
 
 [vinge-novel]: https://www.tor.com/2017/08/03/science-fiction-with-something-for-everyone-a-deepness-in-the-sky-by-vernor-vinge/
-```
+~~~~

exercises/linked-list/instructions.md

@@ -13,7 +13,7 @@ Sometimes a station gets closed down, and in that case the station needs to be r
 
 The size of a route is measured not by how far the train travels, but by how many stations it stops at.
 
-```exercism/note
+~~~~exercism/note
 The linked list is a fundamental data structure in computer science, often used in the implementation of other data structures.
 As the name suggests, it is a list of nodes that are linked together.
 It is a list of "nodes", where each node links to its neighbor or neighbors.
@@ -23,4 +23,4 @@ In a **doubly linked list** each node links to both the node that comes before,
 If you want to dig deeper into linked lists, check out [this article][intro-linked-list] that explains it using nice drawings.
 
 [intro-linked-list]: https://medium.com/basecs/whats-a-linked-list-anyway-part-1-d8b7e6508b9d
-```
+~~~~

exercises/pangram/introduction.md

@@ -7,10 +7,10 @@ To give a comprehensive sense of the font, the random sentences should use **all
 They're running a competition to get suggestions for sentences that they can use.
 You're in charge of checking the submissions to see if they are valid.
 
-```exercism/note
+~~~~exercism/note
 Pangram comes from Greek, παν γράμμα, pan gramma, which means "every letter".
 
 The best known English pangram is:
 
 > The quick brown fox jumps over the lazy dog.
-```
+~~~~

exercises/rational-numbers/description.md

@@ -2,11 +2,11 @@
 
 A rational number is defined as the quotient of two integers `a` and `b`, called the numerator and denominator, respectively, where `b != 0`.
 
-```exercism/note
+~~~~exercism/note
 Note that mathematically, the denominator can't be zero.
 However in many implementations of rational numbers, you will find that the denominator is allowed to be zero with behaviour similar to positive or negative infinity in floating point numbers.
 In those cases, the denominator and numerator generally still can't both be zero at once.
-```
+~~~~
 
 The absolute value `|r|` of the rational number `r = a/b` is equal to `|a|/|b|`.
 

exercises/rna-transcription/instructions.md

@@ -15,6 +15,6 @@ Given a DNA strand, its transcribed RNA strand is formed by replacing each nucle
 - `T` -> `A`
 - `A` -> `U`
 
-```exercism/note
+~~~~exercism/note
 If you want to look at how the inputs and outputs are structured, take a look at the examples in the test suite.
-```
+~~~~