MemoryCache.Testing

Overview

MemoryCache.Testing is a mocking library that creates Microsoft.Extensions.Caching.Memory IMemoryCache system mocks. It's easy to use (usually just a single line of code) with implementations for both Moq and NSubstitute.

Resources

• Source repository
• MemoryCache.Testing.Moq - NuGet
• MemoryCache.Testing.NSubstitute - NuGet

Usage

Start by creating a mocked memory cache using Create.MockedMemoryCache():

var cacheEntryKey = "SomethingInTheCache";
var expectedResult = Guid.NewGuid().ToString();

var mockedCache = Create.MockedMemoryCache();

var actualResult = mockedCache.GetOrCreate(cacheEntryKey, entry => expectedResult);

Assert.AreEqual(expectedResult, actualResult);

This creates a mocked IMemoryCache. If your SUT populates the cache you're done. If it doesn't, or you like your arrange to be verbose, populate it as if you were using the real thing:

var cacheEntryKey = "SomethingInTheCache";
var expectedResult = Guid.NewGuid().ToString();

var mockedCache = Create.MockedMemoryCache();
mockedCache.Set(cacheEntryKey, expectedResult);

var actualResult = mockedCache.Get(cacheEntryKey);

Assert.AreEqual(expectedResult, actualResult);

The Moq implementation of Create.MockedMemoryCache() returns the mocked memory cache. If you need the mock itself (e.g., to verify an invocation) use Mock.Get(mockedCache):

var cacheEntryKey = "SomethingInTheCache";
var expectedResult = Guid.NewGuid().ToString();

var mockedCache = Create.MockedMemoryCache();

var actualResult = mockedCache.GetOrCreate(cacheEntryKey, entry => expectedResult);

var cacheMock = Mock.Get(mockedCache);
cacheMock.Verify(x => x.CreateEntry(cacheEntryKey), Times.Once);
object cacheEntryValue;
cacheMock.Verify(x => x.TryGetValue(cacheEntryKey, out cacheEntryValue), Times.Once);

With regard to verifying invocations, all members of the IMemoryCache interface are mocked.