errors_test.go

Documentation: fmt

		 1  // Copyright 2018 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  package fmt_test
		 6  
		 7  import (
		 8  	"errors"
		 9  	"fmt"
		10  	"testing"
		11  )
		12  
		13  func TestErrorf(t *testing.T) {
		14  	// noVetErrorf is an alias for fmt.Errorf that does not trigger vet warnings for
		15  	// %w format strings.
		16  	noVetErrorf := fmt.Errorf
		17  
		18  	wrapped := errors.New("inner error")
		19  	for _, test := range []struct {
		20  		err				error
		21  		wantText	 string
		22  		wantUnwrap error
		23  	}{{
		24  		err:				fmt.Errorf("%w", wrapped),
		25  		wantText:	 "inner error",
		26  		wantUnwrap: wrapped,
		27  	}, {
		28  		err:				fmt.Errorf("added context: %w", wrapped),
		29  		wantText:	 "added context: inner error",
		30  		wantUnwrap: wrapped,
		31  	}, {
		32  		err:				fmt.Errorf("%w with added context", wrapped),
		33  		wantText:	 "inner error with added context",
		34  		wantUnwrap: wrapped,
		35  	}, {
		36  		err:				fmt.Errorf("%s %w %v", "prefix", wrapped, "suffix"),
		37  		wantText:	 "prefix inner error suffix",
		38  		wantUnwrap: wrapped,
		39  	}, {
		40  		err:				fmt.Errorf("%[2]s: %[1]w", wrapped, "positional verb"),
		41  		wantText:	 "positional verb: inner error",
		42  		wantUnwrap: wrapped,
		43  	}, {
		44  		err:			fmt.Errorf("%v", wrapped),
		45  		wantText: "inner error",
		46  	}, {
		47  		err:			fmt.Errorf("added context: %v", wrapped),
		48  		wantText: "added context: inner error",
		49  	}, {
		50  		err:			fmt.Errorf("%v with added context", wrapped),
		51  		wantText: "inner error with added context",
		52  	}, {
		53  		err:			noVetErrorf("%w is not an error", "not-an-error"),
		54  		wantText: "%!w(string=not-an-error) is not an error",
		55  	}, {
		56  		err:			noVetErrorf("wrapped two errors: %w %w", errString("1"), errString("2")),
		57  		wantText: "wrapped two errors: 1 %!w(fmt_test.errString=2)",
		58  	}, {
		59  		err:			noVetErrorf("wrapped three errors: %w %w %w", errString("1"), errString("2"), errString("3")),
		60  		wantText: "wrapped three errors: 1 %!w(fmt_test.errString=2) %!w(fmt_test.errString=3)",
		61  	}, {
		62  		err:				fmt.Errorf("%w", nil),
		63  		wantText:	 "%!w(<nil>)",
		64  		wantUnwrap: nil, // still nil
		65  	}} {
		66  		if got, want := errors.Unwrap(test.err), test.wantUnwrap; got != want {
		67  			t.Errorf("Formatted error: %v\nerrors.Unwrap() = %v, want %v", test.err, got, want)
		68  		}
		69  		if got, want := test.err.Error(), test.wantText; got != want {
		70  			t.Errorf("err.Error() = %q, want %q", got, want)
		71  		}
		72  	}
		73  }
		74  
		75  type errString string
		76  
		77  func (e errString) Error() string { return string(e) }
		78
View as plain text