{"id":1681,"date":"2017-04-30T10:00:00","date_gmt":"2017-04-30T08:00:00","guid":{"rendered":"https:\/\/demo.sidekick.be\/itenium\/nsubstitute-vs-moq\/"},"modified":"2025-11-28T13:31:46","modified_gmt":"2025-11-28T12:31:46","slug":"nsubstitute-vs-moq","status":"publish","type":"post","link":"https:\/\/demo.sidekick.be\/itenium\/blog\/dotnet\/nsubstitute-vs-moq\/","title":{"rendered":"NSubstitute vs Moq"},"content":{"rendered":"
\/\/ All examples assume\npublic interface ICalculator\n{\n\tint Add(int a, int b);\n\tint Divide(int n, int divisor, out float remainder);\n\tstring Mode { get; set; }\n\tvoid SetMode(string mode);\n}\n\n\/\/ Moq\nMock<ICalculator> moq = new Mock<ICalculator>();\n\n\/\/ NSubstitute\nICalculator nsub = Substitute.For<ICalculator>();\n<\/code><\/pre>\n
Basic example<\/h1>\n
Notice how NSubstitute dropped all the ceremony code required by Moq.<\/p>\n
\/\/ Moq\nvar moq = new Mock<ICalculator>();\nmoq.Setup(calc => calc.Add(1, 2)).Returns(3);\nAssert.AreEqual(3, moq.Object.Add(1, 2));\n\n\/\/ NSubstitute\n\/\/ Saves you a whopping 20 characters :)\nvar nsub = Substitute.For<ICalculator>();\nnsub.Add(1, 2).Returns(3);\nAssert.AreEqual(3, nsub.Add(1, 2));\n<\/code><\/pre>\n
Matching arguments<\/h1>\n
Moq<\/strong><\/p>\n
\/\/ It.\nmoq.Setup(calc => calc.Add(It.IsAny<int>(), It.Is<int>(b => b % 2 == 0))).Returns(3);\n\n\/\/Moq also has\n\/\/- It.IsRegex(\"\", , RegexOptions.IgnoreCase)\n\/\/- It.IsInRange(0, 1, Range.Inclusive)\n<\/code><\/pre>\n
NSubstitute<\/strong><\/p>\n
\/\/ Arg.\nnsub.Add(Arg.Any<int>(), Arg.Is<int>(b => b % 2 == 0)).Returns(3);\n<\/code><\/pre>\n
Verification<\/h1>\n
Moq<\/strong><\/p>\n
moq.Object.Add(1, 1);\nmoq.Object.Add(1, 1);\nmoq.Verify(calc => calc.Add(1, It.IsAny<int>()), Times.Exactly(2));\n\n\/\/ Property\nmoq.VerifyGet(calc => calc.Mode, Times.Never);\n<\/code><\/pre>\n
NSubstitute<\/strong><\/p>\n
nsub.Add(1, 1);\nnsub.Add(1, 1);\nnsub.Received(2).Add(1, Arg.Any<int>());\n\n\/\/ Property\nvar requiredAssignmentForCompiler = nsub.DidNotReceive().Mode;\n<\/code><\/pre>\n
Out and ref<\/h1>\n
ref<\/code> works in both frameworks exactly the same as out<\/code>.<\/p>\n
Moq<\/strong><\/p>\n
float remainder = 0.4F;\nmoq.Setup(calc => calc.Divide(12, 5, out remainder)).Returns(2);\nremainder = 0;\n\nAssert.AreEqual(2, moq.Object.Divide(12, 5, out remainder));\nAssert.AreEqual(0.4F, remainder);\n<\/code><\/pre>\n
NSubstitute<\/strong><\/p>\n
float remainder;\nnsub.Divide(12, 5, out remainder).Returns(x => {\n  x[2] = 0.4F; \/\/ [2] = 3th parameter = remainder\n  return 2;\n});\nremainder = 0;\n\nAssert.AreEqual(2, nsub.Divide(12, 5, out remainder));\nAssert.AreEqual(0.4F, remainder);\n<\/code><\/pre>\n
Exceptions<\/h1>\n
Moq<\/strong><\/p>\n
moq.Setup(calc => calc.Add(1, 1)).Throws<InvalidOperationException>();\nAssert.Throws<InvalidOperationException>(() => moq.Object.Add(1, 1));\n\nmoq.Setup(calc => calc.SetMode(\"HEX\")).Throws(new ArgumentException());\nAssert.Throws<ArgumentException>(() => moq.Object.SetMode(\"HEX\"));\n<\/code><\/pre>\n
NSubstitute<\/strong><\/p>\n
using NSubstitute.ExceptionExtensions;\n\nnsub.Add(1, 1).Throws(new InvalidOperationException());\nAssert.Throws<InvalidOperationException>(() => nsub.Add(1, 1));\n\nnsub.When(x => x.SetMode(\"HEX\")).Throw<ArgumentException>();\nAssert.Throws<ArgumentException>(() => nsub.SetMode(\"HEX\"));\n\n\/\/ The extension method syntax is much cleaner\n\/\/ Without it, the setup becomes the following\nnsub.Add(1, 1).Returns(x => { throw new InvalidOperationException(); });\nnsub.When(x => x.SetMode(\"HEX\")).Do(x => { throw new ArgumentException(); });\n<\/code><\/pre>\n
Summary<\/h1>\n
I find Moqs Func<T1, T2, ...><\/code> overloads they have provided for .Return<\/code> very useful. NSubstitute requires some more typing to achieve the same .Return<\/code> capabilities but you do get to treat methods and properties alike compared to Moq who\u2019s stuck with VerifyGet<\/code>. Because of this NSubstitute got better discoverability inside an IDE while Moq continues to struggle with a whole bunch of deprecated ways of doing things.<\/p>\n
The drop of .Setup()<\/code> and .Object<\/code> for all<\/strong> cases is very win for NSubstitute.<\/p>\n
Also in this series<\/h1>\n