logger tests; verify buffering, flushing, and overflow behavior

build.zig

@@ -34,9 +34,18 @@ pub fn build(b: *std.Build) void
         .target           = target,
     });
 
+    const test_mod = b.createModule(.{
+        .root_source_file = b.path("src/root.zig"),
+        .target           = target,
+        .link_libc        = true,
+    });
+
     mod.addImport("toml", toml_dep.module("toml"));
     mod.addImport("args", args_dep.module("args"));
 
+    test_mod.addImport("toml", toml_dep.module("toml"));
+    test_mod.addImport("args", args_dep.module("args"));
+
     const exe = b.addExecutable(.{
         .name        = "zocket",
         .root_module = b.createModule(.{
@@ -66,20 +75,13 @@ pub fn build(b: *std.Build) void
     }
 
     const mod_tests = b.addTest(.{
-        .root_module = mod,
+        .root_module = test_mod,
     });
 
     const run_mod_tests = b.addRunArtifact(mod_tests);
 
-    const exe_tests  = b.addTest(.{
-        .root_module = exe.root_module,
-    });
-
-    const run_exe_tests = b.addRunArtifact(exe_tests);
-
     const test_step = b.step("test", "Run tests");
     test_step.dependOn(&run_mod_tests.step);
-    test_step.dependOn(&run_exe_tests.step);
 }
 
 fn getGitVersion(b: *std.Build) []const u8

src/logging/log.zig

@@ -147,3 +147,90 @@ pub const Logger = struct {
         try logger.writer.interface.flush();
     }
 };
+
+//
+
+extern fn mkdtemp(template: [*:0]u8) ?[*:0]u8;
+
+fn mktmpdir(buffer: *[64:0]u8, pattern: []const u8) ![]u8
+{
+    if (pattern.len >= buffer.len) return error.PatternTooLong;
+
+    @memcpy(buffer[0..pattern.len], pattern);
+    buffer[pattern.len] = 0;
+
+    const result = mkdtemp(buffer) orelse return error.MkDtempFailed;
+
+    return std.mem.span(result);
+}
+
+test "filtering, buffering and automatic flushing"
+{
+    const io        = std.testing.io;
+    const allocator = std.testing.allocator;
+    const fname     = "logger.test";
+
+    var path_buf: [64:0]u8 = undefined;
+    var read_buf: [512]u8  = undefined;
+
+    const path = try mktmpdir(&path_buf,"/tmp/zocket-test-XXXXXX");
+
+    const dir  = try std.Io.Dir.openDirAbsolute(io, path, .{});
+    defer
+    {
+        dir.deleteFile(io, fname) catch unreachable;
+        dir.close(io);
+        std.Io.Dir.deleteDirAbsolute(io, path) catch unreachable;
+    }
+
+    const file = try dir.createFile(io, fname, .{ .lock = .exclusive });
+    defer file.close(io);
+
+    var log = try Logger.init(allocator, .{
+        .io = io, .buffer = 256, .file = file
+    });
+    defer log.deinit();
+
+    //
+
+    // The file is expected to be empty, as this does not force the internal buffer to auto-flush.
+    log.info("info={d}", .{1});
+
+    {
+        const contents = try dir.readFile(io, fname, &read_buf);
+        try std.testing.expect(contents.len == 0);
+    }
+
+    // The file should include 'info=1' after flushing to disk.
+    try log.flush();
+
+    {
+        const contents = try dir.readFile(io, fname, &read_buf);
+        try std.testing.expectEqualStrings("info=1", contents);
+    }
+    try file.setLength(io, 0);
+    try log.writer.seekTo(0);
+    @memset(read_buf[0..], 0);
+
+    // The file should include 'warn=1' as warnings and errors automatically trigger a flush to disk.
+    log.warn("warn={d}", .{1});
+
+    {
+        const contents = try dir.readFile(io, fname, &read_buf);
+        try std.testing.expectEqualStrings("warn=1", contents);
+    }
+    try file.setLength(io, 0);
+    try log.writer.seekTo(0);
+    @memset(read_buf[0..], 0);
+
+    // The file should include 'info=x...' as it's bigger than the allocated 256 buffer, forcing it to automatically drain on overflow.
+    log.info("info={s}", .{[_]u8{'x'} ** 300});
+
+    {
+        const contents = try dir.readFile(io, fname, &read_buf);
+        try std.testing.expectEqualStrings("info=" ++ ([_]u8{'x'} ** 300), contents);
+    }
+    try file.setLength(io, 0);
+    try log.writer.seekTo(0);
+    @memset(read_buf[0..], 0);
+}

src/root.zig

@@ -8,8 +8,10 @@ pub const memory  = @import("memory/util.zig");
 pub const signals = @import("signals/models.zig");
 pub const logging = @import("logging/log.zig");
 
+//
+
+const std = @import("std");
+
 test {
-    _ = config;
-    _ = memory;
-    _ = signals;
+    std.testing.refAllDecls(@This());
 }