br := NewReaderSize(r, size)
			want := func(s string, wantErr error) {
				p := make([]byte, 50)
				n, err := br.Read(p)
				if err != wantErr || n != len(s) || string(p[:n]) != s {
					t.Fatalf("read(%d) = %q, %v, want %q, %v", len(p), string(p[:n]), err, s, wantErr)
				}
				t.Logf("read(%d) = %q, %v", len(p), string(p[:n]), err)
			}
			want("abc", nil)

		}
		info := &Info{Defs: make(map[*syntax.Name]Object)}
		typecheck(src, &conf, info)
		got := fmt.Sprint(errs)
		if !strings.Contains(got, test.wantErr) {
			t.Errorf("%q: unexpected error: got %q, want substring %q",
				src, got, test.wantErr)
		}

		// Assert that declarations were type checked nonetheless.
		var gotObjs []string
		for id, obj := range info.Defs {
			if obj != nil {