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fix: consistent handling of nil passed to any wrapping function (#4)
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* fix: consistent handling of nil passed to any wrapping function

* Document nil handling in `Wrap`, `WithStack` and `WithCause`
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e-sumin authored Mar 20, 2024
1 parent 541a584 commit 724240f
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6 changes: 6 additions & 0 deletions README.md
Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,8 @@ func Foo() error {

### Adding stack trace
If you are interested in adding information about the line and filename where the sentinel error happened, you can do the following:

**NOTE**: While the `WithStack` will return `nil` if passed `err` equals `nil`, we do not consider this good practice and recommend checking the `err` value before invocation.
```go
func Foo() error {
...
Expand All @@ -47,6 +49,8 @@ func Bar() error {

### Adding error cause information
Sometimes you might be interested in returning a sentinel error, but also add some cause error to it, in such cases you can do the following:

**NOTE**: While the `WithCause` will return `nil` if passed `err` equals `nil`, we do not consider this good practice and recommend checking the `err` value before invocation.
```go
func FetchSomething(ID string) error {
err := doSomething() // Here we have an error
Expand Down Expand Up @@ -74,6 +78,8 @@ func FooBar() error {

### Wrapping an error with a high-level message
Sometimes you might want to add some high-level information to an error before passing it up to the invoker.

**NOTE**: While the `Wrap` will return `nil` if passed `err` equals `nil`, we do not consider this good practice and recommend checking the `err` value before invocation.
```go
func LoadProfile() error {
err := makeAnApiCall()
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4 changes: 4 additions & 0 deletions errors.go
Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,10 @@ func New(message string, details ...any) error {

// Wrap returns a new errkitError that has the given message and err as the cause.
func Wrap(err error, message string, details ...any) error {
if err == nil {
return nil
}

e := newError(errors.New(message), 2, details...)
e.cause = err
return e
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10 changes: 10 additions & 0 deletions errors_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -286,6 +286,16 @@ func TestErrorsWrapping(t *testing.T) {
if wrappedErr != nil {
t.Errorf("nil expected to be returned")
}

wrappedErr = errkit.Wrap(nil, "Some message")
if wrappedErr != nil {
t.Errorf("nil expected to be returned")
}

wrappedErr = errkit.WithStack(nil)
if wrappedErr != nil {
t.Errorf("nil expected to be returned")
}
})
}

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