From e4c1598ac8dd984a480fad41e61cc60c41448cac Mon Sep 17 00:00:00 2001
From: Jacob Young <jacobly@ziglang.org>
Date: Sat, 19 Sep 2026 05:15:45 -0400
Subject: [PATCH] runner: implement error checks

---
 test/incremental2/bad_import | 48 ++++++++++++++++++++++++++++++++++++
 test/src/runner.zig          | 11 ++++++---
 2 files changed, 56 insertions(+), 3 deletions(-)
 create mode 100644 test/incremental2/bad_import

diff --git a/test/incremental2/bad_import b/test/incremental2/bad_import
new file mode 100644
index 0000000000000000000000000000000000000000..d93a9ed6309f963c310a82f0813d0905a564cc10
--- /dev/null
+++ b/test/incremental2/bad_import
@@ -0,0 +1,48 @@
+#exe {
+-Mroot=main.zig
+#}
+
+#write main.zig {
+pub fn main() !void {
+    _ = @import("foo.zig");
+    try std.Io.File.stdout().writeStreamingAll(io, "success\n");
+}
+const std = @import("std");
+const io = std.Io.Threaded.global_single_threaded.io();
+#}
+#write foo.zig {
+comptime {
+    _ = @import("bad.zig");
+}
+#}
+#update
+#check errors {
+bad.zig:1:1: error: unable to load "bad.zig": FileNotFound
+foo.zig:2:17: note: file imported here
+#}
+
+#write foo.zig {
+comptime {
+    _ = @import("this_is/not_real.zig");
+}
+#}
+#update {
+change bad import#}
+#check errors {
+this_is/not_real.zig:1:1: error: unable to load "not_real.zig": FileNotFound
+foo.zig:2:17: note: file imported here
+#}
+
+#write main.zig {
+pub fn main() !void {
+    //_ = @import("foo.zig");
+    try std.Io.File.stdout().writeStreamingAll(io, "success\n");
+}
+const std = @import("std");
+const io = std.Io.Threaded.global_single_threaded.io();
+#}
+#update {
+remove import of 'foo.zig'#}
+#check stdout {
+success
+#}
diff --git a/test/src/runner.zig b/test/src/runner.zig
index 9b652ee72607e48512fe2accce29d3127a6defc1..e4d7e9971fc965bb4724bcdec971a5c1ed754156 100644
--- a/test/src/runner.zig
+++ b/test/src/runner.zig
@@ -749,9 +749,14 @@ fn runTest(
                                 stderr.tossBuffered();
                             }
                             switch (check) {
-                                .errors => if (error_bundle.errorMessageCount() != 0) {
-                                    @panic("TODO");
-                                } else fatal("expected compile errors", .{}),
+                                .errors => {
+                                    var error_aw: std.Io.Writer.Allocating = .init(gpa);
+                                    defer error_aw.deinit();
+                                    try error_bundle.renderToWriter(.{
+                                        .include_source_line = false,
+                                    }, &error_aw.writer);
+                                    try std.testing.expectEqualStrings(expected, error_aw.written());
+                                },
                                 .stdout, .exit, .lldb => if (error_bundle.errorMessageCount() != 0) {
                                     try error_bundle.renderToStderr(io, .{}, .auto);
                                     fatal("unexpected compile errors", .{});
-- 
2.54.0