util: add tests for JoinErrors()

Signed-off-by: Sven Anderson <sven@redhat.com>

internal/util/errors_test.go

@@ -0,0 +1,71 @@
+/*
+Copyright 2020 ceph-csi authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package util
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+)
+
+var (
+	errFoo = errors.New("foo")
+	errBar = errors.New("bar")
+)
+
+func wrapError(e error) error {
+	return fmt.Errorf("w{%w}", e)
+}
+
+func TestJoinErrors(t *testing.T) {
+	assertErrorIs := func(e1, e2 error, ok bool) {
+		if errors.Is(e1, e2) != ok {
+			t.Errorf("errors.Is(e1, e2) != %v - e1: %#v - e2: %#v", ok, e1, e2)
+		}
+	}
+
+	assertErrorIs(errFoo, errBar, false)
+	assertErrorIs(errFoo, errFoo, true)
+
+	fooBar := JoinErrors(errFoo, errBar)
+	assertErrorIs(fooBar, errFoo, true)
+	assertErrorIs(fooBar, errBar, true)
+
+	w2Foo := wrapError(wrapError(errFoo))
+	w1Bar := wrapError(errBar)
+	w1w2Foow1Bar := wrapError(JoinErrors(w2Foo, w1Bar))
+	assertErrorIs(w1w2Foow1Bar, errFoo, true)
+	assertErrorIs(w1w2Foow1Bar, errBar, true)
+
+	w2X := wrapError(wrapError(errors.New("x")))
+	w2FooBar := wrapError(wrapError(fooBar))
+	w1w2Xw2FooBar := wrapError(JoinErrors(w2X, w2FooBar))
+	assertErrorIs(w1w2Xw2FooBar, errFoo, true)
+	assertErrorIs(w1w2Xw2FooBar, errBar, true)
+
+	x := errors.Unwrap(errors.Unwrap(errors.Unwrap(errors.Unwrap(w1w2Xw2FooBar))))
+	assertErrorIs(x, fooBar, true)
+	x = errors.Unwrap(x)
+	assertErrorIs(x, fooBar, false)
+	assertErrorIs(x, errFoo, false)
+	assertErrorIs(x, errBar, true)
+	s1 := "w{w{w{x}}: w{w{foo: bar}}}"
+	s2 := w1w2Xw2FooBar.Error()
+	if s1 != s2 {
+		t.Errorf("%s != %s", s1, s2)
+	}
+}