WhenEmptyTests.cs

// 
// Copyright (c) 2004-2019 Jaroslaw Kowalski <jaak@jkowalski.net>, Kim Christensen, Julian Verdurmen
// 
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without 
// modification, are permitted provided that the following conditions 
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// * Redistributions of source code must retain the above copyright notice, 
//   this list of conditions and the following disclaimer. 
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// * Redistributions in binary form must reproduce the above copyright notice,
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// * Neither the name of Jaroslaw Kowalski nor the names of its 
//   contributors may be used to endorse or promote products derived from this
//   software without specific prior written permission. 
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namespace NLog.UnitTests.LayoutRenderers.Wrappers
{
    using System;
    using NLog;
    using NLog.Layouts;
    using Xunit;

    public class WhenEmptyTests : NLogTestBase
    {
        [Fact]
        public void CoalesceTest()
        {
            SimpleLayout l = @"${message:whenEmpty=<no message>}";

            var le = LogEventInfo.Create(LogLevel.Info, "logger", "message");
            Assert.Equal("message", l.Render(le));

            // empty log message
            var le2 = LogEventInfo.Create(LogLevel.Info, "logger", "");
            Assert.Equal("<no message>", l.Render(le2));
        }

        [Fact]
        public void CoalesceWithANestedLayout()
        {
            SimpleLayout l = @"${message:whenEmpty=${logger} emitted empty message}";

            var le = LogEventInfo.Create(LogLevel.Info, "logger", "message");
            Assert.Equal("message", l.Render(le));

            // empty log message
            var le2 = LogEventInfo.Create(LogLevel.Info, "mylogger", "");
            Assert.Equal("mylogger emitted empty message", l.Render(le2));
        }

        [Fact]
        public void WhenEmpty_MissingInner_ShouldNotThrow()
        {
            LogManager.ThrowExceptions = true;
            SimpleLayout l = @"${whenEmpty:whenEmpty=${literal:text=c:\logs\}:inner=${environment:LOG_DIR_XXX}}api.log";
            var le = LogEventInfo.Create(LogLevel.Info, "logger", "message");
            Assert.Equal("api.log", l.Render(le));
        }

        [Fact]
        public void WhenDbNullRawValueShouldWork()
        {
            SimpleLayout l = @"${event-properties:prop1:whenEmpty=${db-null}}";
            {
                var le = LogEventInfo.Create(LogLevel.Info, "logger", "message");
                le.Properties["prop1"] = 1;
                var success = l.TryGetRawValue(le, out var rawValue);
                Assert.True(success);
                Assert.Equal(1, rawValue);
            }
            // empty log message
            {
                var le = LogEventInfo.Create(LogLevel.Info, "logger", "message");
                var success = l.TryGetRawValue(le, out var rawValue);
                Assert.True(success);
                Assert.Equal(DBNull.Value, rawValue);
            }

        }
    }
}