KevinDockx#130 eTag injector reads streams and requires an eTag gener…

…ator

src/Marvin.Cache.Headers/DefaultETagInjector.cs

@@ -1,3 +1,4 @@
+using System;
 using System.IO;
 using System.Threading.Tasks;
 using Marvin.Cache.Headers.Interfaces;
@@ -14,7 +15,7 @@ public class DefaultETagInjector : IETagInjector
 
     public DefaultETagInjector(IETagGenerator eTagGenerator)
     {
-        _eTagGenerator = eTagGenerator;
+        _eTagGenerator = eTagGenerator ?? throw new ArgumentNullException(nameof(eTagGenerator));
     }
 
     public async Task<ETag> RetrieveETag(ETagContext eTagContext)

test/Marvin.Cache.Headers.Test/Injectors/ETagInjectorFacts.cs

@@ -0,0 +1,51 @@
+// Any comments, input: @KevinDockx
+// Any issues, requests: https://github.com/KevinDockx/HttpCacheHeaders
+
+using System;
+using System.IO;
+using System.Text;
+using System.Threading.Tasks;
+using Marvin.Cache.Headers.Interfaces;
+using Microsoft.AspNetCore.Http;
+using Moq;
+using Xunit;
+
+namespace Marvin.Cache.Headers.Test.Stores;
+
+public class ETagInjectorFacts
+{
+    [Fact]
+    public void Ctor_ThrowsArgumentNullException_WhenETagGeneratorIsNull()
+    {
+        Assert.Throws<ArgumentNullException>(() => new DefaultETagInjector(null));
+    }
+
+    [Theory]
+    [InlineData("payload")]
+    [InlineData("")]
+    public async Task RetrieveETag_Returns_ETag_BasedOnResponseBody(string payload)
+    {
+        // arrange
+        var eTagGenerator = new Mock<IETagGenerator>();
+
+        eTagGenerator
+            .Setup(x => x.GenerateETag(It.IsAny<StoreKey>(), It.IsAny<string>()))
+            .ReturnsAsync(new ETag(ETagType.Strong, "B56"));
+
+        var httpContext = new Mock<IHttpContextAccessor>();
+        httpContext.Setup(x => x.HttpContext.Response.Body)
+            .Returns(new MemoryStream(Encoding.UTF8.GetBytes(payload)));
+
+        var target = new DefaultETagInjector(eTagGenerator.Object);
+
+        // act
+        var result = await target.RetrieveETag(new ETagContext(new StoreKey(), httpContext.Object.HttpContext));
+
+        // assert
+        Assert.NotNull(result);
+        Assert.Equal(ETagType.Strong, result.ETagType);
+        Assert.Equal("B56", result.Value);
+        eTagGenerator.Verify(x => x.GenerateETag(It.IsAny<StoreKey>(), payload), Times.Exactly(1));
+        httpContext.Verify(x => x.HttpContext.Response.Body, Times.AtLeastOnce());
+    }
+}