added Unwrap() []error to CompositeError

This allows to use errors.Is() or As() with CompositeError

Signed-off-by: Frederic BIDON <fredbi@yahoo.com>

go.mod

@@ -1,6 +1,6 @@
 module github.com/go-openapi/errors
 
-require github.com/stretchr/testify v1.6.1
+require github.com/stretchr/testify v1.8.4
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect

go.sum

@@ -1,5 +1,4 @@
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
-github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
@@ -10,12 +9,10 @@ github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e h1:fD57ERR4JtEqsWb
 github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e/go.mod h1:zD1mROLANZcx1PVRCS0qkT7pwLkGfwJo4zjcN/Tysno=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
-github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f h1:BLraFXnmrev5lT+xlilqcH8XK9/i0At2xKjWk4p6zsU=
 gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

schema.go

@@ -120,6 +120,10 @@ func (c *CompositeError) Error() string {
 	return c.message
 }
 
+func (c *CompositeError) Unwrap() []error {
+	return c.Errors
+}
+
 // MarshalJSON implements the JSON encoding interface
 func (c CompositeError) MarshalJSON() ([]byte, error) {
 	return json.Marshal(map[string]interface{}{
@@ -133,7 +137,7 @@ func (c CompositeError) MarshalJSON() ([]byte, error) {
 func CompositeValidationError(errors ...error) *CompositeError {
 	return &CompositeError{
 		code:    CompositeErrorCode,
-		Errors:  append([]error{}, errors...),
+		Errors:  append(make([]error, 0, len(errors)), errors...),
 		message: "validation failure list",
 	}
 }

schema_test.go

@@ -387,10 +387,30 @@ func TestSchemaErrors(t *testing.T) {
 		assert.EqualValues(t, CompositeErrorCode, err.Code())
 		assert.Equal(t, "validation failure list", err.Error())
 
-		err = CompositeValidationError(fmt.Errorf("first error"), fmt.Errorf("second error"))
+		testErr1 := fmt.Errorf("first error")
+		testErr2 := fmt.Errorf("second error")
+		err = CompositeValidationError(testErr1, testErr2)
 		require.Error(t, err)
 		assert.EqualValues(t, CompositeErrorCode, err.Code())
 		assert.Equal(t, "validation failure list:\nfirst error\nsecond error", err.Error())
+
+		require.ErrorIs(t, err, testErr1)
+		require.ErrorIs(t, err, testErr2)
+	})
+
+	t.Run("should set validation name in CompositeValidation error", func(t *testing.T) {
+		err := CompositeValidationError(
+			InvalidContentType("text/html", []string{"application/json"}),
+			CompositeValidationError(
+				InvalidTypeName("y"),
+			),
+		)
+		_ = err.ValidateName("new-name")
+		const expectedMessage = `validation failure list:
+new-name.unsupported media type "text/html", only [application/json] are allowed
+validation failure list:
+new-namey is an invalid type name`
+		assert.Equal(t, expectedMessage, err.Error())
 	})
 
 	t.Run("with PropertyNotAllowed", func(t *testing.T) {