Testing errors, and std.log.err

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Log levels are either dependent on the optimization level (default) or if you’ve provided a log level as a std_options struct in your source file. It looks like you’re not prohibiting this from happening (in this case, I think you may want to go with an errdefer outside of the calling function). Looks like there’s quite a few more things to consider before it does what you want.

Check this out if you already haven’t: Quick overview of Zig's `std.log` · GitHub

Digging into the source a bit more, we’ll find this:

    pub const Level = enum {
    /// Error: something has gone wrong. This might be recoverable or might
    /// be followed by the program exiting.
    err,
    /// Warning: it is uncertain if something has gone wrong or not, but the
    /// circumstances would be worth investigating.
    warn,
    /// Info: general messages about the state of the program.
    info,
    /// Debug: messages only useful for debugging.
    debug,

    /// Returns a string literal of the given level in full text form.
    pub fn asText(comptime self: Level) []const u8 {
        return switch (self) {
            .err => "error",
            .warn => "warning",
            .info => "info",
            .debug => "debug",
        };
    }
};

Then to determine if the log function is enabled, we’ll also see this:

/// Determine if a specific log message level and scope combination are enabled for logging.
pub fn logEnabled(comptime message_level: Level, comptime scope: @Type(.EnumLiteral)) bool {
    inline for (scope_levels) |scope_level| {
        if (scope_level.scope == scope) return @intFromEnum(message_level) <= @intFromEnum(scope_level.level);
    }
    return @intFromEnum(message_level) <= @intFromEnum(level);
}

Basically it’s saying that if you have a message level higher than the designated level, it will return false and bypass logging. You’ll notice that in the scope levels, err is the lowest enum value. That seems to imply that you’ll almost always be logging errors. I think the best thing to do is only log errors on a failed try or using a catch (or even explicitly checking with an if statement)… that’s why I’m recommending errdefer or explicit checks here.

Essentially, the test passing and invoking a logging function with a specific level are independent operations. They both succeeded.

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