Add unit tests, refactor and add new feature to --rate flag

Author: Alexander Zutikov

lib/nbg_exrp/cli.ex

@@ -1,10 +1,15 @@
 defmodule NbgExrp.CLI do
-
   alias NbgExrp.CurrencyParser
 
   @default_currency "GEL"
 
   def main(argv) do
+    argv
+    |> fetch_and_process
+    |> format_output
+  end
+
+  def fetch_and_process(argv) do
     argv
     |> parse_args
     |> process
@@ -13,20 +18,21 @@ defmodule NbgExrp.CLI do
   def parse_args(argv) do
     OptionParser.parse(argv,
       strict: [help: :boolean, rate: :string, convert: :string],
-      aliases: [h: :help, r: :rate, c: :convert])
+      aliases: [h: :help, r: :rate, c: :convert]
+    )
     |> parse_flag()
   end
 
-  def parse_flag({ [ {flag, value} ], other, _}) do
-    { flag, value, other }
+  def parse_flag({[{flag, value}], other, _}) do
+    {flag, value, other}
   end
 
   def parse_flag({[], _, _}) do
-    { :help, true, true }
+    {:help, true, true}
   end
 
-  def process({ :help, _, _}) do
-    IO.puts """
+  def process({:help, _, _}) do
+    IO.puts("""
     DESCRIPION
 
     -h, --help
@@ -39,20 +45,34 @@ defmodule NbgExrp.CLI do
     -c, --convert
      Desc: Convert amount in currenty to GEL
      Usage: nbg_exrp -c 10 usd, nbg_exrp --conver 10 usd
-    """
+    """)
 
     System.halt(0)
   end
 
-  def process({:rate, currency, _}) do
-    rec = currency |> CurrencyParser.parse
+  def process({:rate, currency, other}) do
+    records = [currency | other] |> CurrencyParser.parse()
 
-    IO.puts "1 #{@default_currency} = #{rec["rate"]} #{rec["code"]} (#{rec["name"]})"
+    {:rate, records}
   end
 
-  def process({:convert, amount, [currency|_]}) do
+  def process({:convert, amount, currency}) do
     total = currency |> CurrencyParser.parse_and_calculate(amount)
 
-    IO.puts "#{amount} #{currency} = #{total} #{@default_currency}"
+    {:convert, [%{total: total, amount: amount, currency: currency}]}
+  end
+
+  def format_output({:rate, records}) do
+    records
+    |> Enum.each(fn rec ->
+      IO.puts("1 #{@default_currency} = #{rec["rate"]} #{rec["code"]} (#{rec["name"]})")
+    end)
+  end
+
+  def format_output({:convert, records}) do
+    records
+    |> Enum.each(fn rec ->
+      IO.puts("#{rec[:amount]} #{rec[:currency]} = #{rec[:total]} #{@default_currency}")
+    end)
   end
 end

lib/nbg_exrp/currency_parser.ex

@@ -1,46 +1,49 @@
 defmodule NbgExrp.CurrencyParser do
   @nbg_resource "https://nbg.gov.ge/gw/api/ct/monetarypolicy/currencies/ka/json"
 
-  def parse(currency) do
+  def parse(currencies) do
     fetch_currencies()
-    |> filter_by(currency)
+    |> filter_by(currencies)
   end
 
   def parse_and_calculate(currency, amount) do
     currency |> parse |> calculate(amount)
   end
 
-  def calculate(rec, amount) do
+  def calculate([rec | _], amount) do
     Decimal.mult(Decimal.new(to_string(rec["rate"])), Decimal.new(amount))
   end
 
   def fetch_currencies do
     case HTTPoison.get(@nbg_resource) do
       {:ok, %HTTPoison.Response{status_code: 200, body: body}} ->
-	Jason.decode! body
+	Jason.decode!(body)
+
       {:ok, %HTTPoison.Response{status_code: 404}} ->
-	IO.puts "Not found :("
+	IO.puts("Not found :(")
 	System.halt(0)
+
       {:error, %HTTPoison.Error{reason: reason}} ->
-	IO.inspect reason
+	IO.inspect(reason)
 	System.halt(0)
     end
   end
 
-  def filter_by([currencies|_], currency) do
-    Map.fetch(currencies, "currencies")
+  def filter_by([crecords | _], currencies) do
+    normalized_currencies = Enum.map(currencies, &String.upcase/1)
+
+    Map.fetch(crecords, "currencies")
     |> elem(1)
-    |> Enum.filter(fn rec -> rec["code"] == String.upcase(currency) end)
-    |> first
+    |> Enum.filter(fn rec -> Enum.member?(normalized_currencies, rec["code"]) end)
+    |> validate
   end
 
-  def first([rec|_]) do
-    rec
+  def validate([a | b]) do
+    [a | b]
   end
 
-  def first([]) do
-    IO.puts "No info"
+  def validate([]) do
+    IO.puts("No info")
     System.halt(0)
   end
-
 end

mix.exs

@@ -24,7 +24,8 @@ defmodule NbgExrp.MixProject do
     [
       {:jason, "~> 1.2"},
       {:httpoison, "~> 1.8"},
-      {:decimal, "~> 2.0"}
+      {:decimal, "~> 2.0"},
+      {:mock, "~> 0.3.0", only: :test}
     ]
   end
 

mix.lock

@@ -6,9 +6,11 @@
   "httpoison": {:hex, :httpoison, "1.8.0", "6b85dea15820b7804ef607ff78406ab449dd78bed923a49c7160e1886e987a3d", [:mix], [{:hackney, "~> 1.17", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm", "28089eaa98cf90c66265b6b5ad87c59a3729bea2e74e9d08f9b51eb9729b3c3a"},
   "idna": {:hex, :idna, "6.1.1", "8a63070e9f7d0c62eb9d9fcb360a7de382448200fbbd1b106cc96d3d8099df8d", [:rebar3], [{:unicode_util_compat, "~>0.7.0", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm", "92376eb7894412ed19ac475e4a86f7b413c1b9fbb5bd16dccd57934157944cea"},
   "jason": {:hex, :jason, "1.2.2", "ba43e3f2709fd1aa1dce90aaabfd039d000469c05c56f0b8e31978e03fa39052", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "18a228f5f0058ee183f29f9eae0805c6e59d61c3b006760668d8d18ff0d12179"},
+  "meck": {:hex, :meck, "0.9.2", "85ccbab053f1db86c7ca240e9fc718170ee5bda03810a6292b5306bf31bae5f5", [:rebar3], [], "hexpm", "81344f561357dc40a8344afa53767c32669153355b626ea9fcbc8da6b3045826"},
   "metrics": {:hex, :metrics, "1.0.1", "25f094dea2cda98213cecc3aeff09e940299d950904393b2a29d191c346a8486", [:rebar3], [], "hexpm", "69b09adddc4f74a40716ae54d140f93beb0fb8978d8636eaded0c31b6f099f16"},
   "mimerl": {:hex, :mimerl, "1.2.0", "67e2d3f571088d5cfd3e550c383094b47159f3eee8ffa08e64106cdf5e981be3", [:rebar3], [], "hexpm", "f278585650aa581986264638ebf698f8bb19df297f66ad91b18910dfc6e19323"},
   "mint": {:hex, :mint, "1.3.0", "396b3301102f7b775e103da5a20494b25753aed818d6d6f0ad222a3a018c3600", [:mix], [{:castore, "~> 0.1.0", [hex: :castore, repo: "hexpm", optional: true]}], "hexpm", "a9aac960562e43ca69a77e5176576abfa78b8398cec5543dd4fb4ab0131d5c1e"},
+  "mock": {:hex, :mock, "0.3.7", "75b3bbf1466d7e486ea2052a73c6e062c6256fb429d6797999ab02fa32f29e03", [:mix], [{:meck, "~> 0.9.2", [hex: :meck, repo: "hexpm", optional: false]}], "hexpm", "4da49a4609e41fd99b7836945c26f373623ea968cfb6282742bcb94440cf7e5c"},
   "parse_trans": {:hex, :parse_trans, "3.3.1", "16328ab840cc09919bd10dab29e431da3af9e9e7e7e6f0089dd5a2d2820011d8", [:rebar3], [], "hexpm", "07cd9577885f56362d414e8c4c4e6bdf10d43a8767abb92d24cbe8b24c54888b"},
   "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.6", "cf344f5692c82d2cd7554f5ec8fd961548d4fd09e7d22f5b62482e5aeaebd4b0", [:make, :mix, :rebar3], [], "hexpm", "bdb0d2471f453c88ff3908e7686f86f9be327d065cc1ec16fa4540197ea04680"},
   "unicode_util_compat": {:hex, :unicode_util_compat, "0.7.0", "bc84380c9ab48177092f43ac89e4dfa2c6d62b40b8bd132b1059ecc7232f9a78", [:rebar3], [], "hexpm", "25eee6d67df61960cf6a794239566599b09e17e668d3700247bc498638152521"},

nbg_exrp

@@ -0,0 +1,89 @@
+defmodule CLITest do
+  use ExUnit.Case, async: false
+
+  alias NbgExrp.CLI
+
+  doctest CLI
+
+  import Mock
+
+  describe "with passed flag" do
+    test "--rate usd returns currency" do
+      with_mock HTTPoison, get: fn _url -> response() end do
+        {:rate, [rec | _]} = CLI.fetch_and_process(["--rate", "usd"])
+
+        assert rec["code"] == "USD"
+      end
+    end
+
+    test "-r usd returns currency" do
+      with_mock HTTPoison, get: fn _url -> response() end do
+        {:rate, [rec | _]} = CLI.fetch_and_process(["-r", "usd"])
+
+        assert rec["code"] == "USD"
+      end
+    end
+
+    test "-r usd eur returns currencies" do
+      with_mock HTTPoison, get: fn _url -> response() end do
+        {:rate, crecords} = CLI.fetch_and_process(["-r", "usd", "eur"])
+
+        assert length(crecords) == 2
+      end
+    end
+
+    test "--convert 10 usd returnes converted currency" do
+      with_mock HTTPoison, get: fn _url -> response() end do
+        {:convert, [rec | _]} = CLI.fetch_and_process(["--convert", 10, "usd"])
+
+        assert Map.has_key?(rec, :total) == true
+        assert rec[:amount] == 10
+      end
+    end
+
+    test "-c 10 usd returnes converted currency" do
+      with_mock HTTPoison, get: fn _url -> response() end do
+        {:convert, [rec | _]} = CLI.fetch_and_process(["-c", 10, "usd"])
+
+        assert Map.has_key?(rec, :total) == true
+        assert rec[:amount] == 10
+      end
+    end
+  end
+
+  defp response do
+    result = [
+      %{
+        "date" => "2021-08-26T00:00:00.000Z",
+        "currencies" => [
+          %{
+            "code" => "EUR",
+            "date" => "2021-08-26T17:45:03.649Z",
+            "diff" => 0.0077,
+            "diffFormated" => "0.0077",
+            "name" => "ევრო",
+            "quantity" => 1,
+            "rate" => 3.6842,
+            "rateFormated" => "3.6842",
+            "validFromDate" => "2021-08-27T00:00:00.000Z"
+          },
+          %{
+            "code" => "USD",
+            "date" => "2021-08-26T17:45:03.649Z",
+            "diff" => -0.0017,
+            "diffFormated" => "0.0017",
+            "name" => "აშშ დოლარი",
+            "quantity" => 1,
+            "rate" => 3.1288,
+            "rateFormated" => "3.1288",
+            "validFromDate" => "2021-08-27T00:00:00.000Z"
+          }
+        ]
+      }
+    ]
+
+    {:ok, body} = Jason.encode(result)
+
+    {:ok, %HTTPoison.Response{status_code: 200, body: body}}
+  end
+end