58 lines
2.1 KiB
Go
58 lines
2.1 KiB
Go
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// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
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// SPDX-License-Identifier: MIT
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package base
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import (
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"errors"
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"strings"
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"testing"
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)
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// TestWrapErrCarriesTagOnce pins the WrapErr contract the ten wrap
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// points rely on: the message carries the tensor tag and the operation
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// once each, whatever the inner error already carries, and the chain
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// stays open for errors.Is. The wrap these properties answer to used to
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// be fmt.Errorf("op: %w", err) over an Errf-built cause, which printed
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// the tag twice.
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func TestWrapErrCarriesTagOnce(t *testing.T) {
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if got := WrapErr("Anything", nil); got != nil {
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t.Fatalf("WrapErr of nil = %v, want nil", got)
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}
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// A bare cause the library did not build: the tag and the operation
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// are added, once each.
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bare := errors.New("the caller's own failure")
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got := WrapErr("Jacobian", bare)
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if want := "tensor: Jacobian: the caller's own failure"; got.Error() != want {
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t.Errorf("WrapErr of a bare cause = %q, want %q", got.Error(), want)
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}
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if !errors.Is(got, bare) {
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t.Errorf("WrapErr of a bare cause does not unwrap to it")
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}
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// A cause the library already tagged: the tag is not doubled.
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tagged := Errf("the shape holds more elements than fit in an index")
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got = WrapErr("Tile", tagged)
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if want := "tensor: Tile: the shape holds more elements than fit in an index"; got.Error() != want {
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t.Errorf("WrapErr of a tagged cause = %q, want %q", got.Error(), want)
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}
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if !errors.Is(got, tagged) {
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t.Errorf("WrapErr of a tagged cause does not unwrap to it")
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}
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if n := strings.Count(got.Error(), "tensor: "); n != 1 {
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t.Errorf("WrapErr message carries the tag %d times, want exactly one", n)
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}
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// A nested WrapErr composes the same way: each layer names its own
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// operation and the tag still appears once.
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inner := WrapErr("Concat", tagged)
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got = WrapErr("Repeat", inner)
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if want := "tensor: Repeat: Concat: the shape holds more elements than fit in an index"; got.Error() != want {
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t.Errorf("nested WrapErr = %q, want %q", got.Error(), want)
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}
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if !errors.Is(got, tagged) {
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t.Errorf("nested WrapErr does not unwrap down to the cause")
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}
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}
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