Roslyn-based analysis for code using the Serilog logging library. Checks for common mistakes and usage problems.

You can get the SerilogAnalyzer from various sources:

• Grab the VSIX from the releases list.
• Install it from Visual Studio Gallery.
• Install the NuGet package into your project.

Checks that exceptions are passed to the exception argument, and not as a normal property, with a code fix to correct it.

Detected incorrect usage:

catch (Exception ex)
{
   Log.Error("Could not save {File}: {Error}", file, ex);
}

The ex parameter is an exception, which Serilog has special handling for if passed as the first argument.

Correct usage:

catch (Exception ex)
{
   Log.Error(ex, "Could not save {File}", file);
}

Checks message templates for correct syntax and emits an error if there's a violation of the templating syntax.

Detected incorrect usage:

Log.Information("Saving {File to {Directory}", file, directory);

The first property token in the message template, File, is malformed.

Correct usage:

Log.Information("Saving {File} to {Directory}", file, directory);

Checks coherence between the message template tokens and the supplied arguments.

Detected incorrect usage:

Log.Information("Saving {File} to {Directory}", file);

Here the number of arguments passed to the method (1) is less than the number of tokens in the message template (2), so the second token in the message template, {Directory}, will have no value.

Correct usage:

Log.Information("Saving {File} to {Directory}", file, directory);

Each property named in the message template needs to correspond to exactly one argument.

Checks that message templates are constant strings. This ensures that events with different data/format arguments can still be detected as instances of the same event.

Detected incorrect usage:

var errorMessage = TryToCheckOutOrder(...); // etc.
Log.Error(errorMessage);

Because errorMessage generally contains failure-specific text ("Couldn't find order 123" ... then 124, then 125) the group of occurrences can't be located using the message template/event type.

This also degrades Serilog performance by filling its internal message template cache.

Correct usage:

Log.Error("Order handler failed with {HandlerError}", errorMessage);

Correct usage is to always pass any variable data as a property to a message template. A CodeFix is provided that converts string interpolation ($"{...}"), String.Format(...) and string concat ("value: " + value) to a message template

Checks that all property names in a message template are unique.

Detected incorrect usage:

Log.Information("Saving {Path} to {Path}", file, directory); 

In this example, because both properties in the message template have the same name, Serilog can only record one of them.

Correct usage:

Log.Information("Saving {File} to {Directory}", file, directory); 

Each property in a message template must have a unique name.

Checks that all property names in a message template are PascalCased.

Detected incorrect usage:

Log.Information("Saving {file} to {directory}", file, directory); 

A CodeFix is provided, that applies pascal casing.

Correct usage:

Log.Information("Saving {File} to {Directory}", file, directory); 

Checks that all anonymous objects passed to the logger are destructured.

Detected incorrect usage:

Log.Information("Saving {File} to {Directory}", new { Name = name, Size = size }, directory); 

A CodeFix is provided, that applies the destructuring hint.

Correct usage:

Log.Information("Saving {@File} to {Directory}", new { Name = name, Size = size }, directory); 

Checks that contextual loggers are constructed with the correct type.

Detected incorrect usage:

class A
{
    private static readonly ILogger Logger = Logger.ForContext<B>();
}

class B {}

A CodeFix is provided, that uses the correct type.

Correct usage:

class A
{
    private static readonly ILogger Logger = Logger.ForContext<A>();
}

class B {} 

Performs static analysis on a fluent LoggerConfiguration call to generate configuration for use with either <appSettings> or appSettings.json