fix error wrapping

src/ErrCtx.zig

@@ -31,12 +31,18 @@ pub fn write(self: *ErrCtx, bytes: []const u8) error{}!usize {
 
 const Writer = std.io.Writer(*ErrCtx, error{}, write);
 
-pub fn writer(self: *ErrCtx) Writer {
+fn writer(self: *ErrCtx) Writer {
     return Writer{ .context = self };
 }
 
 pub fn print(self: *ErrCtx, comptime format: []const u8, args: anytype) void {
-    self.writer().print(format, args) catch unreachable;
+    var buf: [capacity]u8 = undefined;
+    var buf_stream = std.io.fixedBufferStream(&buf);
+    buf_stream.writer().print(format, args) catch |err| switch (err) {
+        error.NoSpaceLeft => {},
+    };
+
+    _ = self.write(buf[0..buf_stream.pos]) catch unreachable;
 }
 
 pub fn returnf(
@@ -117,10 +123,10 @@ test "almost overflow" {
 
 test "rev" {
     var ctx = ErrCtx{};
-    ctx.print("yadda", .{});
+    ctx.print("yadda {s}", .{"xx"});
 
     var it = ctx.rev();
-    try testing.expectEqualSlices(u8, "yadda", it.next().?);
+    try testing.expectEqualStrings("yadda xx", it.next().?);
     try testing.expectEqual(it.next(), null);
 }
 

src/unix2db/main.zig

@@ -151,31 +151,25 @@ test "trivial error: missing passwd file" {
 
     const exit_code = execute(allocator, stdout.writer(), stderr.writer(), args[0..]);
     try testing.expectEqual(@as(u8, 1), exit_code);
-    try testing.expectEqualSlices(
-        u8,
-        stderr.items,
-        "ERROR FileNotFound: ./passwd: open \n",
-    );
+    try testing.expectEqualStrings(stderr.items, "ERROR FileNotFound: ./passwd: open \n");
 }
 
 test "fail" {
     var errc = ErrCtx{};
-    var stderr = ArrayList(u8).init(testing.allocator);
-    defer stderr.deinit();
-    var stderrw = stderr.writer();
-    const exit_code = fail(errc.wrapf("got 1", .{}), stderrw, error.NotSure);
+    var buf = ArrayList(u8).init(testing.allocator);
+    defer buf.deinit();
+    var wr = buf.writer();
+    const exit_code = fail(errc.wrapf("invalid user 'foo'", .{}), wr, error.NotSure);
     try testing.expectEqual(exit_code, 1);
-    try testing.expectEqualSlices(
-        u8,
-        stderr.items,
-        "ERROR NotSure: got 1\n",
-    );
+    try testing.expectEqualStrings(buf.items, "ERROR NotSure: invalid user 'foo'\n");
 }
 
 test "smoke test" {
     const allocator = testing.allocator;
     var stderr = ArrayList(u8).init(allocator);
     defer stderr.deinit();
+    var stdout = ArrayList(u8).init(allocator);
+    defer stdout.deinit();
 
     var corpus = try Corpus.testCorpus(allocator);
     defer corpus.deinit();
@@ -225,8 +219,8 @@ test "smoke test" {
         "--output", outPath,
     };
 
+    const exit_code = execute(allocator, stdout.writer(), stderr.writer(), args);
     if (true) return error.SkipZigTest;
-    const exit_code = try execute(allocator, stderr.writer(), args);
-
+    try testing.expectEqualStrings("", stderr.items);
     try testing.expectEqual(@as(u8, 0), exit_code);
 }