Update Dockerfile and changelog for Crystal 1.19.1 and add test for parallism

Author: meatball133

Dockerfile

@@ -1,4 +1,4 @@
-FROM crystallang/crystal:1.18.2-alpine
+FROM crystallang/crystal:1.19.1-alpine
 
 # install packages required to run the tests
 RUN apk add --no-cache bash jq coreutils

changelog.md

@@ -1,6 +1,6 @@
-# 2.1.3
+# 2.2.0
 
-- Move to Crystal 1.19.x
+- Move to Crystal 1.19.1
 - Add support for parallel testing
 
 # 2.1.2

tests/parallel-letter-frequency/.meta/config.json

@@ -0,0 +1,12 @@
+{
+  "files": {
+    "solution": [
+      "src/parallel_letter_frequency.cr"
+    ],
+    "test": [
+      "spec/parallel_letter_frequency_spec.cr"
+    ]
+  },
+  "blurb": "Create a sentence of the form \"One for X, one for me.\".",
+  "source_url": "https://github.com/exercism/problem-specifications/issues/757"
+}

tests/parallel-letter-frequency/expected_results.json

@@ -0,0 +1,36 @@
+{
+  "version": 3,
+  "status": "pass",
+  "tests": [
+    {
+      "name": "ParallelLetterFrequency no texts",
+      "status": "pass",
+      "test_code": "input = [] of String\nexpected = {} of String => Int32\nParallelLetterFrequency.calculate_frequencies(input).should eq(expected)"
+    },
+    {
+      "name": "ParallelLetterFrequency one text with one letter",
+      "status": "pass",
+      "test_code": "input = [\"a\"]\nexpected = {\"a\" => 1}\nParallelLetterFrequency.calculate_frequencies(input).should eq(expected)"
+    },
+    {
+      "name": "ParallelLetterFrequency one text with multiple letters",
+      "status": "pass",
+      "test_code": "input = [\"bbcccd\"]\nexpected = {\"b\" => 2, \"c\" => 3, \"d\" => 1}\nParallelLetterFrequency.calculate_frequencies(input).should eq(expected)"
+    },
+    {
+      "name": "ParallelLetterFrequency two texts with one letter",
+      "status": "pass",
+      "test_code": "input = [\"e\", \"f\"]\nexpected = {\"e\" => 1, \"f\" => 1}\nParallelLetterFrequency.calculate_frequencies(input).should eq(expected)"
+    },
+    {
+      "name": "ParallelLetterFrequency two texts with multiple letters",
+      "status": "pass",
+      "test_code": "input = [\"ggh\", \"hhi\"]\nexpected = {\"g\" => 2, \"h\" => 3, \"i\" => 1}\nParallelLetterFrequency.calculate_frequencies(input).should eq(expected)"
+    },
+    {
+      "name": "ParallelLetterFrequency ignore letter casing",
+      "status": "pass",
+      "test_code": "input = [\"m\", \"M\"]\nexpected = {\"m\" => 2}\nParallelLetterFrequency.calculate_frequencies(input).should eq(expected)"
+    }
+  ]
+}

tests/parallel-letter-frequency/spec/parallel_letter_frequency_spec.cr

@@ -0,0 +1,40 @@
+require "spec"
+require "../src/*"
+
+describe "ParallelLetterFrequency" do
+  it "no texts" do
+    input = [] of String
+    expected = {} of String => Int32
+    ParallelLetterFrequency.calculate_frequencies(input).should eq(expected)
+  end
+
+  pending "one text with one letter" do
+    input = ["a"]
+    expected = {"a" => 1}
+    ParallelLetterFrequency.calculate_frequencies(input).should eq(expected)
+  end
+
+  pending "one text with multiple letters" do
+    input = ["bbcccd"]
+    expected = {"b" => 2, "c" => 3, "d" => 1}
+    ParallelLetterFrequency.calculate_frequencies(input).should eq(expected)
+  end
+
+  pending "two texts with one letter" do
+    input = ["e", "f"]
+    expected = {"e" => 1, "f" => 1}
+    ParallelLetterFrequency.calculate_frequencies(input).should eq(expected)
+  end
+
+  pending "two texts with multiple letters" do
+    input = ["ggh", "hhi"]
+    expected = {"g" => 2, "h" => 3, "i" => 1}
+    ParallelLetterFrequency.calculate_frequencies(input).should eq(expected)
+  end
+
+  pending "ignore letter casing" do
+    input = ["m", "M"]
+    expected = {"m" => 2}
+    ParallelLetterFrequency.calculate_frequencies(input).should eq(expected)
+  end
+end

tests/parallel-letter-frequency/src/parallel_letter_frequency.cr

@@ -0,0 +1,34 @@
+require "sync/shared"
+
+class ParallelLetterFrequency
+  def self.calculate_frequencies(input : Array(String)) : Hash(String, Int32)
+    data : Sync::Shared(Hash(String, Int32)) = Sync::Shared.new({} of String => Int32)
+    channel = Channel(Nil).new
+    input.each do |text|
+      spawn do
+        local = Hash(String, Int32).new(0)
+
+        text.each_char do |char|
+          next unless char.letter?
+          local[char.downcase.to_s] += 1
+        end
+
+        data.replace do |shared_data|
+          local.each do |char, count|
+            shared_data[char] ||= 0
+            shared_data[char] += count
+          end
+          shared_data
+        end
+        channel.send(nil)  # signal completion
+      end
+    end
+
+    input.size.times do
+      channel.receive
+    end
+
+
+    data.get()
+  end
+end