Replaced test config file with env var.

Author: adriangodong

Medium.Tests/Client.cs

@@ -15,7 +15,7 @@ public class Client
 
         public Client() {
             var configuration = new ConfigurationBuilder().
-                AddJsonFile("config.json").
+                AddEnvironmentVariables("MEDIUMSDK_").
                 Build();
             _accessToken =  configuration["AccessToken"];
             _testPublicationId = configuration["TestPublicationId"];

Medium.Tests/Medium.Tests.csproj

@@ -10,21 +10,15 @@
     <IsPackable>False</IsPackable>
   </PropertyGroup>
 
-  <ItemGroup>
-    <None Update="config.json">
-      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
-    </None>
-  </ItemGroup>
-
   <ItemGroup>
     <ProjectReference Include="..\Medium\Medium.csproj" />
   </ItemGroup>
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.Configuration.EnvironmentVariables" Version="1.1.2" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.3.0" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.2.0" />
     <PackageReference Include="Microsoft.Extensions.Configuration" Version="1.1.2" />
-    <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="1.1.2" />
     <PackageReference Include="xunit" Version="2.2.0" />
   </ItemGroup>