Check if the tests actually pass under the current compiler

.gitignore

@@ -1 +1,3 @@
 build
+zig-cache
+zig-out

grammar/build.zig

@@ -0,0 +1,35 @@
+const std = @import("std");
+
+const test_targets = [_]std.Target.Query{
+    .{},
+};
+
+pub fn build(b: *std.Build) !void {
+    const test_step = b.step("test", "Test the tests");
+
+    var files = std.ArrayList([]const u8).init(b.allocator);
+    defer files.deinit();
+
+    var dir = try std.fs.cwd().openDir("tests", .{ .iterate = true });
+    var it = dir.iterate();
+    while (try it.next()) |file| {
+        if (file.kind != .file) {
+            continue;
+        }
+        try files.append(b.dupe(file.name));
+    }
+
+    for (test_targets) |target| {
+        for (files.items) |file| {
+            const unit_test = b.addTest(.{
+                .root_source_file = .{ .path = file },
+                .target = b.resolveTargetQuery(target),
+            });
+
+            const run_unit_test = b.addRunArtifact(unit_test);
+            test_step.dependOn(&run_unit_test.step);
+        }
+    }
+
+    b.default_step.dependOn(test_step);
+}

grammar/tests/while.zig

@@ -137,48 +137,42 @@ fn getNumberOrNull() ?i32 {
 test "while on optional with else result follow else prong" {
     const result = while (returnNull()) |value| {
         break value;
-    } else
-        @as(i32, 2);
+    } else @as(i32, 2);
     expect(result == 2);
 }
 
 test "while on optional with else result follow break prong" {
     const result = while (returnOptional(10)) |value| {
         break value;
-    } else
-        @as(i32, 2);
+    } else @as(i32, 2);
     expect(result == 10);
 }
 
 test "while on error union with else result follow else prong" {
     const result = while (returnError()) |value| {
         break value;
-    } else |err|
-        @as(i32, 2);
+    } else |err| @as(i32, 2);
     expect(result == 2);
 }
 
 test "while on error union with else result follow break prong" {
     const result = while (returnSuccess(10)) |value| {
         break value;
-    } else |err|
-        @as(i32, 2);
+    } else |err| @as(i32, 2);
     expect(result == 10);
 }
 
 test "while on bool with else result follow else prong" {
     const result = while (returnFalse()) {
         break @as(i32, 10);
-    } else
-        @as(i32, 2);
+    } else @as(i32, 2);
     expect(result == 2);
 }
 
 test "while on bool with else result follow break prong" {
     const result = while (returnTrue()) {
         break @as(i32, 10);
-    } else
-        @as(i32, 2);
+    } else @as(i32, 2);
     expect(result == 10);
 }