examples

test/examples/humanized_weather_test.exs

@@ -0,0 +1,26 @@
+defmodule MyApp.HumanizedWeatherTest do
+  use ExUnit.Case, async: true
+
+  alias MyApp.HumanizedWeather
+  alias MyApp.WeatherAPI
+
+  test "gets and formats temperature" do
+    protomock =
+      ProtoMock.new()
+      |> ProtoMock.expect(&WeatherAPI.temperature/2, fn _lat_long -> {:ok, 30} end)
+
+    assert HumanizedWeather.display_temp({50.06, 19.94}, protomock) ==
+             "Current temperature is 30 degrees"
+
+    ProtoMock.verify!(protomock)
+  end
+
+  test "gets and formats humidity" do
+    protomock =
+      ProtoMock.new()
+      |> ProtoMock.stub(&WeatherAPI.humidity/2, fn _lat_long -> {:ok, 60} end)
+
+    assert HumanizedWeather.display_humidity({50.06, 19.94}, protomock) ==
+            "Current humidity is 60%"
+  end
+end

test/support/weather_api.ex

@@ -0,0 +1,59 @@
+defprotocol MyApp.WeatherAPI do
+  @type lat_long :: {float(), float()}
+  @type api_result :: {:ok, integer()} | {:error, any()}
+
+  @spec temperature(t(), lat_long()) :: api_result()
+  def temperature(weather_api, lat_long)
+
+  @spec humidity(t(), lat_long()) :: api_result()
+  def humidity(weather_api, lat_long)
+end
+
+defmodule AcmeWeather.ApiConfig do
+  defstruct []
+end
+
+defmodule AcmeWeather.Client do
+  def get_temperature(_lat, _long, _config), do: 0
+  def get_humidity(_lat, _long, _config), do: 0
+end
+
+defimpl MyApp.WeatherAPI, for: AcmeWeather.ApiConfig do
+  def temperature(api_config, {lat, long}) do
+    AcmeWeather.Client.get_temperature(lat, long, api_config)
+  end
+
+  def humidity(api_config, {lat, long}) do
+    AcmeWeather.Client.get_humidity(lat, long, api_config)
+  end
+end
+
+defimpl MyApp.WeatherAPI, for: ProtoMock do
+  def temperature(protomock, lat_long) do
+    ProtoMock.invoke(protomock, &MyApp.WeatherAPI.temperature/2, [lat_long])
+  end
+
+  def humidity(protomock, lat_long) do
+    ProtoMock.invoke(protomock, &MyApp.WeatherAPI.humidity/2, [lat_long])
+  end
+end
+
+# ProtoMock.create_impl(MyApp.WeatherAPI)
+
+defmodule MyApp.HumanizedWeather do
+  alias MyApp.WeatherAPI
+
+  def display_temp({lat, long}, weather_api \\ default_weather_api()) do
+    {:ok, temp} = WeatherAPI.temperature(weather_api, {lat, long})
+    "Current temperature is #{temp} degrees"
+  end
+
+  def display_humidity({lat, long}, weather_api \\ default_weather_api()) do
+    {:ok, humidity} = WeatherAPI.humidity(weather_api, {lat, long})
+    "Current humidity is #{humidity}%"
+  end
+
+  defp default_weather_api() do
+    Application.get_env(MyApp, :weather_api)
+  end
+end