Run example solutions on CI

.github/workflows/test.yml

@@ -0,0 +1,23 @@
+name: Test
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  ci:
+    runs-on: ubuntu-20.04
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - uses: erlef/[email protected]
+        with:
+          otp-version: "23.2"
+          gleam-version: "0.24.0"
+
+      - name: Run tests for all exercises
+        run: bin/test

bin/test

@@ -0,0 +1,66 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+# Synopsis:
+# Test the track's exercises.
+# 
+# At a minimum, this file must check if the example/exemplar solution of each 
+# Practice/Concept Exercise passes the exercise's tests.
+#
+# To check this, you usually have to (temporarily) replace the exercise's solution files
+# with its exemplar/example files.
+#
+# If your track uses skipped tests, make sure to (temporarily) enable these tests
+# before running the tests.
+#
+# The path to the solution/example/exemplar files can be found in the exercise's
+# .meta/config.json file, or possibly inferred from the exercise's directory name.
+
+# Example:
+# ./bin/test
+
+exit_code=0
+
+function verify_exercise {
+  local dir slug implementation_file stub_backup_file module
+  dir=$(realpath "$1")
+  slug=$(basename "${dir}")
+  module=${slug//-/_}
+  implementation_file="${dir}/.meta/example.gleam"
+  stub_file="${dir}/src/${module}.gleam"
+  stub_backup_file="${stub_file}.bak"
+
+  cp "${stub_file}" "${stub_backup_file}"
+  cp "${implementation_file}" "${stub_file}"
+
+  if ! (cd "$dir" && gleam test)
+  then
+    echo "${slug}: proof solution did not pass the tests"
+    exit_code=1
+  fi
+
+  mv "${stub_backup_file}" "${stub_file}"
+}
+
+# Verify the Concept Exercises
+for concept_exercise_dir in ./exercises/concept/*/
+do
+  if [ -d "$concept_exercise_dir" ]
+  then
+    echo "Checking $(basename "${concept_exercise_dir}") concept exercise..."
+    verify_exercise "${concept_exercise_dir}"
+  fi
+done
+
+# Verify the Practice Exercises
+for practice_exercise_dir in ./exercises/practice/*/
+do
+  if [ -d "$practice_exercise_dir" ]
+  then
+    echo "Checking $(basename "${practice_exercise_dir}") practice exercise..."
+    verify_exercise "${practice_exercise_dir}"
+  fi
+done
+
+exit ${exit_code}

exercises/practice/bowling/.meta/example.gleam

@@ -1,5 +1,4 @@
 import gleam/list
-import gleam/bool
 import gleam/result
 
 pub opaque type Frame {
@@ -26,7 +25,7 @@ fn is_frame_rolls_valid(frame: Frame) -> Bool {
 }
 
 fn is_frame_open(frame: Frame) -> Bool {
-  list.length(frame.rolls) == 2 && frame.rolls(score_rolls) < 10
+  list.length(frame.rolls) == 2 && score_rolls(frame.rolls) < 10
 }
 
 fn is_frame_strike(frame: Frame) -> Bool {

exercises/practice/forth/.meta/example.gleam

@@ -1,9 +1,6 @@
-import gleam/result
-import gleam/io
 import gleam/int
 import gleam/map
 import gleam/order
-import gleam/bool
 import gleam/list
 import gleam/string
 import gleam/string_builder

exercises/practice/forth/src/forth.gleam

@@ -1,5 +1,3 @@
-import gleam/result
-
 pub type Forth {
   Forth
 }

exercises/practice/forth/test/forth_test.gleam

@@ -1,7 +1,5 @@
 import forth
 import gleam/result
-import gleam/list
-import gleam/io
 import gleeunit
 import gleeunit/should
 

exercises/practice/freelancer-rates/.meta/example.gleam

@@ -7,15 +7,20 @@ pub fn daily_rate(hourly_rate: Int) -> Float {
 
 pub fn apply_discount(before_discount: Int, discount: Float) -> Float {
   let float_discount = int.to_float(before_discount)
-  float_discount -. {float_discount *. {discount /. 100.0}}
+  float_discount -. float_discount *. { discount /. 100.0 }
 }
 
 pub fn monthly_rate(hourly_rate: Int, discount: Float) -> Int {
   let before_discount = float.round(daily_rate(hourly_rate) *. 22.0)
-    let after_discount = apply_discount(before_discount, discount)
-    float.truncate(float.ceiling(after_discount))
+  let after_discount = apply_discount(before_discount, discount)
+  float.truncate(float.ceiling(after_discount))
 }
 
 pub fn days_in_budget(budget: Int, hourly_rate: Int, discount: Float) -> Float {
-     float.floor( int.to_float(budget) /. apply_discount(float.round(daily_rate(hourly_rate)), discount))
-}
+  float.floor(
+    int.to_float(budget) /. apply_discount(
+      float.round(daily_rate(hourly_rate)),
+      discount,
+    ),
+  )
+}