examples: add example for sometimes assertions

examples/sometimes_assertions.zig

@@ -0,0 +1,50 @@
+const std = @import("std");
+const Io = std.Io;
+
+const Simulator = @import("zigmulator");
+const assertSometimes = Simulator.assertSometimes;
+
+const Winner = enum {
+    worker_a,
+    worker_b,
+};
+
+var winner: ?Winner = null;
+
+fn workerA(init: std.process.Init) anyerror!void {
+    if (winner == null)
+        winner = .worker_a;
+
+    assertSometimes(winner == .worker_a, @src(), "worker A won the startup race");
+
+    var stdout = Io.File.stdout().writerStreaming(init.io, &.{});
+    try stdout.interface.writeAll("worker A observed the winner\n");
+    try stdout.interface.flush();
+}
+
+fn workerB(init: std.process.Init) anyerror!void {
+    if (winner == null)
+        winner = .worker_b;
+
+    assertSometimes(winner == .worker_b, @src(), "worker B won the startup race");
+
+    var stdout = Io.File.stdout().writerStreaming(init.io, &.{});
+    try stdout.interface.writeAll("worker B observed the winner\n");
+    try stdout.interface.flush();
+}
+
+pub fn main(init: std.process.Init) !void {
+    winner = null;
+
+    var sim: Simulator = undefined;
+    sim.init(std.heap.page_allocator, init.io, 0);
+    defer sim.deinit();
+
+    try sim.addExecutable("worker_a", workerA);
+    try sim.addExecutable("worker_b", workerB);
+
+    try sim.spawn("worker_a", .{});
+    try sim.spawn("worker_b", .{});
+
+    while (sim.scheduleOne()) {}
+}