Feature/adding some re route specific validation tests (#590)

* started refactoring json config validation stack because ive made it crap

* inject validators from DI rather than instanciating, next step mock them

* added some unit tests for specific validators on the train yey

test/Ocelot.UnitTests/Configuration/Validation/HostAndPortValidatorTests.cs

@@ -0,0 +1,78 @@
+using System;
+using FluentValidation.Results;
+using Ocelot.Configuration.File;
+using Ocelot.Configuration.Validator;
+using Shouldly;
+using TestStack.BDDfy;
+using Xunit;
+
+namespace Ocelot.UnitTests.Configuration.Validation
+{
+    public class HostAndPortValidatorTests
+    {
+        private HostAndPortValidator _validator;
+        private ValidationResult _result;
+        private FileHostAndPort _hostAndPort;
+
+        public HostAndPortValidatorTests()
+        {
+            _validator = new HostAndPortValidator();
+        }
+
+        [Theory]
+        [InlineData(null)]
+        [InlineData("")]
+        public void should_be_invalid_because_host_empty(string host)
+        {
+            var fileHostAndPort = new FileHostAndPort
+            {
+                Host = host
+            };
+
+            this.Given(_ => GivenThe(fileHostAndPort))
+               .When(_ => WhenIValidate())
+               .Then(_ => ThenTheResultIsInValid())
+               .And(_ => ThenTheErorrIs())
+               .BDDfy();
+        }
+
+        [Fact]
+        public void should_be_valid_because_host_set()
+        {
+            var fileHostAndPort = new FileHostAndPort
+            {
+                Host = "test"
+            };
+
+            this.Given(_ => GivenThe(fileHostAndPort))
+                .When(_ => WhenIValidate())
+                .Then(_ => ThenTheResultIsValid())
+                .BDDfy();
+        }
+
+        private void GivenThe(FileHostAndPort hostAndPort)
+        {
+            _hostAndPort = hostAndPort;
+        }
+
+        private void WhenIValidate()
+        {
+            _result = _validator.Validate(_hostAndPort);
+        }
+
+        private void ThenTheResultIsValid()
+        {
+            _result.IsValid.ShouldBeTrue();
+        }
+
+        private void ThenTheErorrIs()
+        {
+            _result.Errors[0].ErrorMessage.ShouldBe("When not using service discovery Host must be set on DownstreamHostAndPorts if you are not using ReRoute.Host or Ocelot cannot find your service!");
+        }
+
+        private void ThenTheResultIsInValid()
+        {
+            _result.IsValid.ShouldBeFalse();
+        }
+    }
+}