Handle when the script fails due there is not internet connection or due an unexpected error

lib/ex_tldr.ex

@@ -3,6 +3,8 @@ defmodule ExTldr do
   Documentation for ExTldr, an Elixir client for tldr-pages.
   """
 
+  @http_client Application.get_env(:ex_tldr, :http_client, HTTPoison)
+
   @doc """
   Wrapper for the CLI of the ExTldr client. 
   """
@@ -62,7 +64,7 @@ defmodule ExTldr do
   end
 
   defp describe(os, term) do
-    case HTTPoison.get(process_url(os, term)) do
+    case @http_client.get(process_url(os, term)) do
       {:ok, %HTTPoison.Response{status_code: 200, body: body}} ->
         IO.puts(body)
 
@@ -71,16 +73,19 @@ defmodule ExTldr do
           "Term \"#{term}\" not found on \"#{os}\" pages\nExTldr is looking on \"common\" pages."
         )
 
-        case HTTPoison.get(process_url("common", term)) do
+        case @http_client.get(process_url("common", term)) do
           {:ok, %HTTPoison.Response{status_code: 200, body: body}} ->
             IO.puts(body)
 
           {:ok, %HTTPoison.Response{status_code: 404}} ->
             IO.puts("Term not found on \"common\" pages.")
         end
 
-      {:error, %HTTPoison.Error{reason: reason}} ->
-        IO.inspect(reason)
+      {:error, %HTTPoison.Error{reason: reason}} when reason == :nxdomain ->
+        raise NoInternetConnectionError
+
+      {:error, %HTTPoison.Error{reason: reason}} when reason != :nxdomain ->
+        raise UnexpectedError, reason
     end
   end
 end

lib/ex_tldr/exceptions.ex

@@ -0,0 +1,9 @@
+defmodule NoInternetConnectionError do
+  defexception message:
+                 "There is not internet connection or there are problems with the connection."
+end
+
+defmodule UnexpectedError do
+  defexception message:
+                 "An unexpected error has occurred. If you want, you can report it in https://github.com/tldr-pages/extldr\nIf you do it, please, share the error shown below."
+end

mix.exs

@@ -37,6 +37,7 @@ defmodule ExTldr.MixProject do
   defp deps do
     [
       {:httpoison, "~> 1.6"},
+      {:mox, "~> 0.5.2"},
       {:excoveralls, "~> 0.12.3", only: :test},
       {:inch_ex, only: [:docs, :test]}
     ]

mix.lock

@@ -1,15 +1,25 @@
 %{
   "bunt": {:hex, :bunt, "0.2.0", "951c6e801e8b1d2cbe58ebbd3e616a869061ddadcc4863d0a2182541acae9a38", [:mix], [], "hexpm", "7af5c7e09fe1d40f76c8e4f9dd2be7cebd83909f31fee7cd0e9eadc567da8353"},
+  "bypass": {:hex, :bypass, "1.0.0", "b78b3dcb832a71aca5259c1a704b2e14b55fd4e1327ff942598b4e7d1a7ad83d", [:mix], [{:plug, "~> 1.7", [hex: :plug, repo: "hexpm", optional: false]}, {:plug_cowboy, "~> 1.0 or ~> 2.0", [hex: :plug_cowboy, repo: "hexpm", optional: false]}], "hexpm", "5a1dc855dfcc86160458c7a70d25f65d498bd8012bd4c06a8d3baa368dda3c45"},
   "certifi": {:hex, :certifi, "2.5.1", "867ce347f7c7d78563450a18a6a28a8090331e77fa02380b4a21962a65d36ee5", [:rebar3], [{:parse_trans, "~>3.3", [hex: :parse_trans, repo: "hexpm", optional: false]}], "hexpm", "805abd97539caf89ec6d4732c91e62ba9da0cda51ac462380bbd28ee697a8c42"},
+  "cowboy": {:hex, :cowboy, "2.7.0", "91ed100138a764355f43316b1d23d7ff6bdb0de4ea618cb5d8677c93a7a2f115", [:rebar3], [{:cowlib, "~> 2.8.0", [hex: :cowlib, repo: "hexpm", optional: false]}, {:ranch, "~> 1.7.1", [hex: :ranch, repo: "hexpm", optional: false]}], "hexpm", "04fd8c6a39edc6aaa9c26123009200fc61f92a3a94f3178c527b70b767c6e605"},
+  "cowlib": {:hex, :cowlib, "2.8.0", "fd0ff1787db84ac415b8211573e9a30a3ebe71b5cbff7f720089972b2319c8a4", [:rebar3], [], "hexpm", "79f954a7021b302186a950a32869dbc185523d99d3e44ce430cd1f3289f41ed4"},
   "excoveralls": {:hex, :excoveralls, "0.12.3", "2142be7cb978a3ae78385487edda6d1aff0e482ffc6123877bb7270a8ffbcfe0", [:mix], [{:hackney, "~> 1.0", [hex: :hackney, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm", "568a3e616c264283f5dea5b020783ae40eef3f7ee2163f7a67cbd7b35bcadada"},
   "hackney": {:hex, :hackney, "1.15.2", "07e33c794f8f8964ee86cebec1a8ed88db5070e52e904b8f12209773c1036085", [:rebar3], [{:certifi, "2.5.1", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "6.0.0", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "1.0.1", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "~>1.1", [hex: :mimerl, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "1.1.5", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}], "hexpm", "e0100f8ef7d1124222c11ad362c857d3df7cb5f4204054f9f0f4a728666591fc"},
   "httpoison": {:hex, :httpoison, "1.6.2", "ace7c8d3a361cebccbed19c283c349b3d26991eff73a1eaaa8abae2e3c8089b6", [:mix], [{:hackney, "~> 1.15 and >= 1.15.2", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm", "aa2c74bd271af34239a3948779612f87df2422c2fdcfdbcec28d9c105f0773fe"},
   "idna": {:hex, :idna, "6.0.0", "689c46cbcdf3524c44d5f3dde8001f364cd7608a99556d8fbd8239a5798d4c10", [:rebar3], [{:unicode_util_compat, "0.4.1", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm", "4bdd305eb64e18b0273864920695cb18d7a2021f31a11b9c5fbcd9a253f936e2"},
   "inch_ex": {:hex, :inch_ex, "2.1.0-rc.1", "7642a8902c0d2ed5d9b5754b2fc88fedf630500d630fc03db7caca2e92dedb36", [:mix], [{:bunt, "~> 0.2", [hex: :bunt, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm", "4ceee988760f9382d1c1d0b93ea5875727f6071693e89a0a3c49c456ef1be75d"},
   "jason": {:hex, :jason, "1.2.1", "12b22825e22f468c02eb3e4b9985f3d0cb8dc40b9bd704730efa11abd2708c44", [:mix], [{:decimal, "~> 1.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "b659b8571deedf60f79c5a608e15414085fa141344e2716fbd6988a084b5f993"},
   "metrics": {:hex, :metrics, "1.0.1", "25f094dea2cda98213cecc3aeff09e940299d950904393b2a29d191c346a8486", [:rebar3], [], "hexpm", "69b09adddc4f74a40716ae54d140f93beb0fb8978d8636eaded0c31b6f099f16"},
+  "mime": {:hex, :mime, "1.3.1", "30ce04ab3175b6ad0bdce0035cba77bba68b813d523d1aac73d9781b4d193cf8", [:mix], [], "hexpm", "6cbe761d6a0ca5a31a0931bf4c63204bceb64538e664a8ecf784a9a6f3b875f1"},
   "mimerl": {:hex, :mimerl, "1.2.0", "67e2d3f571088d5cfd3e550c383094b47159f3eee8ffa08e64106cdf5e981be3", [:rebar3], [], "hexpm", "f278585650aa581986264638ebf698f8bb19df297f66ad91b18910dfc6e19323"},
+  "mox": {:hex, :mox, "0.5.2", "55a0a5ba9ccc671518d068c8dddd20eeb436909ea79d1799e2209df7eaa98b6c", [:mix], [], "hexpm", "df4310628cd628ee181df93f50ddfd07be3e5ecc30232d3b6aadf30bdfe6092b"},
   "parse_trans": {:hex, :parse_trans, "3.3.0", "09765507a3c7590a784615cfd421d101aec25098d50b89d7aa1d66646bc571c1", [:rebar3], [], "hexpm", "17ef63abde837ad30680ea7f857dd9e7ced9476cdd7b0394432af4bfc241b960"},
+  "plug": {:hex, :plug, "1.10.0", "6508295cbeb4c654860845fb95260737e4a8838d34d115ad76cd487584e2fc4d", [:mix], [{:mime, "~> 1.0", [hex: :mime, repo: "hexpm", optional: false]}, {:plug_crypto, "~> 1.1.1 or ~> 1.2", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4", [hex: :telemetry, repo: "hexpm", optional: true]}], "hexpm", "422a9727e667be1bf5ab1de03be6fa0ad67b775b2d84ed908f3264415ef29d4a"},
+  "plug_cowboy": {:hex, :plug_cowboy, "2.2.1", "fcf58aa33227a4322a050e4783ee99c63c031a2e7f9a2eb7340d55505e17f30f", [:mix], [{:cowboy, "~> 2.7", [hex: :cowboy, repo: "hexpm", optional: false]}, {:plug, "~> 1.7", [hex: :plug, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "3b43de24460d87c0971887286e7a20d40462e48eb7235954681a20cee25ddeb6"},
+  "plug_crypto": {:hex, :plug_crypto, "1.1.2", "bdd187572cc26dbd95b87136290425f2b580a116d3fb1f564216918c9730d227", [:mix], [], "hexpm", "6b8b608f895b6ffcfad49c37c7883e8df98ae19c6a28113b02aa1e9c5b22d6b5"},
+  "ranch": {:hex, :ranch, "1.7.1", "6b1fab51b49196860b733a49c07604465a47bdb78aa10c1c16a3d199f7f8c881", [:rebar3], [], "hexpm", "451d8527787df716d99dc36162fca05934915db0b6141bbdac2ea8d3c7afc7d7"},
   "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.5", "6eaf7ad16cb568bb01753dbbd7a95ff8b91c7979482b95f38443fe2c8852a79b", [:make, :mix, :rebar3], [], "hexpm", "13104d7897e38ed7f044c4de953a6c28597d1c952075eb2e328bc6d6f2bfc496"},
+  "telemetry": {:hex, :telemetry, "0.4.1", "ae2718484892448a24470e6aa341bc847c3277bfb8d4e9289f7474d752c09c7f", [:rebar3], [], "hexpm", "4738382e36a0a9a2b6e25d67c960e40e1a2c95560b9f936d8e29de8cd858480f"},
   "unicode_util_compat": {:hex, :unicode_util_compat, "0.4.1", "d869e4c68901dd9531385bb0c8c40444ebf624e60b6962d95952775cac5e90cd", [:rebar3], [], "hexpm", "1d1848c40487cdb0b30e8ed975e34e025860c02e419cb615d255849f3427439d"},
 }

test/ex_tldr_test.exs

@@ -1,8 +1,13 @@
 defmodule ExTldrTest do
   use ExUnit.Case
   import ExUnit.CaptureIO
+  alias ClientMock
   doctest ExTldr
 
+  import Mox
+
+  setup :verify_on_exit!
+
   test "look for a linux command" do
     execute_main = fn ->
       ExTldr.main(["linux", "adduser"])
@@ -58,4 +63,12 @@ defmodule ExTldrTest do
 
     assert capture_io(execute_main) =~ "Usage:"
   end
+
+  #test "should return lack of internet" do
+    # assert_raise NoInternetConnectionError,
+    #             fn ->
+    #               ClientMock
+    #               |> expect(:get, fn _ -> {:error, %HTTPoison.Error{reason: :nxdomain}} end)
+    #             end
+  #end
 end

test/test_helper.exs

@@ -1 +1,6 @@
 ExUnit.start()
+
+Mox.defmock(
+  ClientMock,
+  for: HTTPoison.Base
+)