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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package fmt_test
import (
"errors"
"fmt"
"reflect"
"testing"
)
func TestErrorf(t *testing.T) {
// noVetErrorf is an alias for fmt.Errorf that does not trigger vet warnings for
// %w format strings.
noVetErrorf := fmt.Errorf
wrapped := errors.New("inner error")
for _, test := range []struct {
err error
wantText string
wantUnwrap error
wantSplit []error
}{{
err: fmt.Errorf("%w", wrapped),
wantText: "inner error",
wantUnwrap: wrapped,
}, {
err: fmt.Errorf("added context: %w", wrapped),
wantText: "added context: inner error",
wantUnwrap: wrapped,
}, {
err: fmt.Errorf("%w with added context", wrapped),
wantText: "inner error with added context",
wantUnwrap: wrapped,
}, {
err: fmt.Errorf("%s %w %v", "prefix", wrapped, "suffix"),
wantText: "prefix inner error suffix",
wantUnwrap: wrapped,
}, {
err: fmt.Errorf("%[2]s: %[1]w", wrapped, "positional verb"),
wantText: "positional verb: inner error",
wantUnwrap: wrapped,
}, {
err: fmt.Errorf("%v", wrapped),
wantText: "inner error",
}, {
err: fmt.Errorf("added context: %v", wrapped),
wantText: "added context: inner error",
}, {
err: fmt.Errorf("%v with added context", wrapped),
wantText: "inner error with added context",
}, {
err: noVetErrorf("%w is not an error", "not-an-error"),
wantText: "%!w(string=not-an-error) is not an error",
}, {
err: noVetErrorf("wrapped two errors: %w %w", errString("1"), errString("2")),
wantText: "wrapped two errors: 1 2",
wantSplit: []error{errString("1"), errString("2")},
}, {
err: noVetErrorf("wrapped three errors: %w %w %w", errString("1"), errString("2"), errString("3")),
wantText: "wrapped three errors: 1 2 3",
wantSplit: []error{errString("1"), errString("2"), errString("3")},
}, {
err: noVetErrorf("wrapped nil error: %w %w %w", errString("1"), nil, errString("2")),
wantText: "wrapped nil error: 1 %!w(<nil>) 2",
wantSplit: []error{errString("1"), errString("2")},
}, {
err: noVetErrorf("wrapped one non-error: %w %w %w", errString("1"), "not-an-error", errString("3")),
wantText: "wrapped one non-error: 1 %!w(string=not-an-error) 3",
wantSplit: []error{errString("1"), errString("3")},
}, {
err: fmt.Errorf("wrapped errors out of order: %[3]w %[2]w %[1]w", errString("1"), errString("2"), errString("3")),
wantText: "wrapped errors out of order: 3 2 1",
wantSplit: []error{errString("1"), errString("2"), errString("3")},
}, {
err: fmt.Errorf("wrapped several times: %[1]w %[1]w %[2]w %[1]w", errString("1"), errString("2")),
wantText: "wrapped several times: 1 1 2 1",
wantSplit: []error{errString("1"), errString("2")},
}, {
err: fmt.Errorf("%w", nil),
wantText: "%!w(<nil>)",
wantUnwrap: nil, // still nil
}} {
if got, want := errors.Unwrap(test.err), test.wantUnwrap; got != want {
t.Errorf("Formatted error: %v\nerrors.Unwrap() = %v, want %v", test.err, got, want)
}
if got, want := splitErr(test.err), test.wantSplit; !reflect.DeepEqual(got, want) {
t.Errorf("Formatted error: %v\nUnwrap() []error = %v, want %v", test.err, got, want)
}
if got, want := test.err.Error(), test.wantText; got != want {
t.Errorf("err.Error() = %q, want %q", got, want)
}
}
}
func splitErr(err error) []error {
if e, ok := err.(interface{ Unwrap() []error }); ok {
return e.Unwrap()
}
return nil
}
type errString string
func (e errString) Error() string { return string(e) }
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