IConfigurationMock.cs

var mockConfiguration = new Mock<IConfiguration>();

// Set up the GetSection method to return a Mock<IConfigurationSection>
mockConfiguration.Setup(config => config.GetSection(It.IsAny<string>()))
    .Returns(new Mock<IConfigurationSection>().Object); // returns a new Mock IConfigurationSection object

// Set up the Value property of the IConfigurationSection to return a specific value
mockConfiguration.Setup(config => config[It.IsAny<string>()])
    .Returns("YourValue"); // returns "YourValue"