Merge pull request #7 from umairidris/wrapf
Add Wrapf
diff --git a/errors.go b/errors.go
index 30b5885..00f8df1 100644
--- a/errors.go
+++ b/errors.go
@@ -147,6 +147,20 @@
}
}
+// Wrapf returns an error annotating the cause with the format specifier.
+// If cause is nil, Wrapf returns nil.
+func Wrapf(cause error, format string, args ...interface{}) error {
+ if cause == nil {
+ return nil
+ }
+ pc, _, _, _ := runtime.Caller(1)
+ return &e{
+ cause: cause,
+ message: fmt.Sprintf(format, args...),
+ loc: loc(pc),
+ }
+}
+
type causer interface {
Cause() error
}
diff --git a/errors_test.go b/errors_test.go
index 5eed1d5..c54bec1 100644
--- a/errors_test.go
+++ b/errors_test.go
@@ -130,6 +130,9 @@
}, {
err: Wrap(Wrap(x, "message"), "another message"),
want: "github.com/pkg/errors/errors_test.go:131: another message\ngithub.com/pkg/errors/errors_test.go:131: message\ngithub.com/pkg/errors/errors_test.go:106: error\n",
+ }, {
+ err: Wrapf(x, "message"),
+ want: "github.com/pkg/errors/errors_test.go:134: message\ngithub.com/pkg/errors/errors_test.go:106: error\n",
}}
for i, tt := range tests {
@@ -141,3 +144,29 @@
}
}
}
+
+func TestWrapfNil(t *testing.T) {
+ got := Wrapf(nil, "no error")
+ if got != nil {
+ t.Errorf("Wrapf(nil, \"no error\"): got %#v, expected nil", got)
+ }
+}
+
+func TestWrapf(t *testing.T) {
+ tests := []struct {
+ err error
+ message string
+ want string
+ }{
+ {io.EOF, "read error", "read error: EOF"},
+ {Wrapf(io.EOF, "read error without format specifiers"), "client error", "client error: read error without format specifiers: EOF"},
+ {Wrapf(io.EOF, "read error with %d format specifier", 1), "client error", "client error: read error with 1 format specifier: EOF"},
+ }
+
+ for _, tt := range tests {
+ got := Wrapf(tt.err, tt.message).Error()
+ if got != tt.want {
+ t.Errorf("Wrapf(%v, %q): got: %v, want %v", tt.err, tt.message, got, tt.want)
+ }
+ }
+}
diff --git a/example_test.go b/example_test.go
index 168cb96..088d009 100644
--- a/example_test.go
+++ b/example_test.go
@@ -54,3 +54,11 @@
// github.com/pkg/errors/example_test.go:34: inner
// github.com/pkg/errors/example_test.go:33: error
}
+
+func ExampleWrapf() {
+ cause := errors.New("whoops")
+ err := errors.Wrapf(cause, "oh noes #%d", 2)
+ fmt.Println(err)
+
+ // Output: oh noes #2: whoops
+}
