go120_test.go

Documentation: golang.org/x/sync/errgroup

     1  // Copyright 2023 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build go1.20
     6  
     7  package errgroup_test
     8  
     9  import (
    10  	"context"
    11  	"errors"
    12  	"testing"
    13  
    14  	"golang.org/x/sync/errgroup"
    15  )
    16  
    17  func TestCancelCause(t *testing.T) {
    18  	errDoom := errors.New("group_test: doomed")
    19  
    20  	cases := []struct {
    21  		errs []error
    22  		want error
    23  	}{
    24  		{want: nil},
    25  		{errs: []error{nil}, want: nil},
    26  		{errs: []error{errDoom}, want: errDoom},
    27  		{errs: []error{errDoom, nil}, want: errDoom},
    28  	}
    29  
    30  	for _, tc := range cases {
    31  		g, ctx := errgroup.WithContext(context.Background())
    32  
    33  		for _, err := range tc.errs {
    34  			err := err
    35  			g.TryGo(func() error { return err })
    36  		}
    37  
    38  		if err := g.Wait(); err != tc.want {
    39  			t.Errorf("after %T.TryGo(func() error { return err }) for err in %v\n"+
    40  				"g.Wait() = %v; want %v",
    41  				g, tc.errs, err, tc.want)
    42  		}
    43  
    44  		if tc.want == nil {
    45  			tc.want = context.Canceled
    46  		}
    47  
    48  		if err := context.Cause(ctx); err != tc.want {
    49  			t.Errorf("after %T.TryGo(func() error { return err }) for err in %v\n"+
    50  				"context.Cause(ctx) = %v; tc.want %v",
    51  				g, tc.errs, err, tc.want)
    52  		}
    53  	}
    54  }
    55
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