Add operation_id to errors

This patch changes the code generator so that errors support the
`operation_id` attribute. This attribute and the existing ones will now
be used to generate more complete error messages. For example, the
following JSON error response:

```
{
  "kind": "Error",
  "id": "401",
  "href": "/api/clusters_mgmt/v1/errors/401",
  "code": "CLUSTERS-MGMT-401",
  "reason": "My reason",
  "operation_id": "456"
}
```

Will result in the following error string (in one single line):

```
identifier is '401', code is 'CLUSTERS-MGMT-401' and
operation identifier is '456': My reason
```

Related: openshift-online/ocm-sdk-go#150
Signed-off-by: Juan Hernandez <jhernand@redhat.com>

pkg/generators/golang/errors_generator.go

@@ -172,7 +172,9 @@ func (g *ErrorsGenerator) generateCommonErrors() error {
 	}
 
 	// Generate the code:
+	g.buffer.Import("fmt", "")
 	g.buffer.Import("io", "")
+	g.buffer.Import("strings", "")
 	g.buffer.Import("github.com/golang/glog", "")
 	g.buffer.Import("github.com/openshift-online/ocm-api-metamodel/pkg/runtime", "")
 	g.buffer.Import(g.packages.HelpersImport(), "")
@@ -185,57 +187,67 @@ func (g *ErrorsGenerator) generateCommonErrors() error {
 
 		// ErrorBuilder is a builder for the error type.
 		type ErrorBuilder struct{
-			id     *string
-			href   *string
-			code   *string
-			reason *string
+			id          *string
+			href        *string
+			code        *string
+			reason      *string
+			operationID *string
 		}
 
 		// Error represents errors.
 		type Error struct {
-			id     *string
-			href   *string
-			code   *string
-			reason *string
+			id          *string
+			href        *string
+			code        *string
+			reason      *string
+			operationID *string
 		}
 
-		// NewError returns a new ErrorBuilder
+		// NewError creates a new builder that can then be used to create error objects.
 		func NewError() *ErrorBuilder {
-			return new(ErrorBuilder)
+			return &ErrorBuilder{}
 		}
 
-		// ID sets the id field for the ErrorBuilder
-		func (e *ErrorBuilder) ID(id string) *ErrorBuilder {
-			e.id = &id
-			return e
+		// ID sets the identifier of the error.
+		func (b *ErrorBuilder) ID(value string) *ErrorBuilder {
+			b.id = &value
+			return b
 		}
 
-		// HREF sets the href field for the ErrorBuilder
-		func (e *ErrorBuilder) HREF(href string) *ErrorBuilder {
-			e.href = &href
-			return e
+		// HREF sets the link of the error.
+		func (b *ErrorBuilder) HREF(value string) *ErrorBuilder {
+			b.href = &value
+			return b
 		}
 
-		// Code sets the cpde field for the ErrorBuilder
-		func (e *ErrorBuilder) Code(code string) *ErrorBuilder {
-			e.code = &code
-			return e
+		// Code sets the code of the error.
+		func (b *ErrorBuilder) Code(value string) *ErrorBuilder {
+			b.code = &value
+			return b
 		}
 
-		// Reason sets the reason field for the ErrorBuilder
-		func (e *ErrorBuilder) Reason(reason string) *ErrorBuilder {
-			e.reason = &reason
-			return e
+		// Reason sets the reason of the error.
+		func (b *ErrorBuilder) Reason(value string) *ErrorBuilder {
+			b.reason = &value
+			return b
 		}
 
-		// Build builds a new error type or returns an error.
-		func (e *ErrorBuilder) Build() (*Error, error) {
-			err := new(Error)
-			err.reason = e.reason
-			err.code = e.code
-			err.id = e.id
-			err.href = e.href
-			return err, nil
+		// OperationID sets the identifier of the operation that caused the error.
+		func (b *ErrorBuilder) OperationID(value string) *ErrorBuilder {
+			b.operationID = &value
+			return b
+		}
+
+		// Build uses the information stored in the builder to create a new error object.
+		func (b *ErrorBuilder) Build() (result *Error,  err error) {
+			result = &Error{
+				id:          b.id,
+				href:        b.href,
+				code:        b.code,
+				reason:      b.reason,
+				operationID: b.operationID,
+			}
+			return
 		}
 
 		// Kind returns the name of the type of the error.
@@ -318,22 +330,57 @@ func (g *ErrorsGenerator) generateCommonErrors() error {
 			return
 		}
 
+		// OperationID returns the identifier of the operation that caused the error.
+		func (e *Error) OperationID() string {
+			if e != nil && e.operationID != nil {
+				return *e.operationID
+			}
+			return ""
+		}
+
+		// GetOperationID returns the identifier of the operation that caused the error and
+		// a flag indicating if that identifier does have a value.
+		func (e *Error) GetOperationID() (value string, ok bool) {
+			ok = e != nil && e.operationID != nil
+			if ok {
+				value = *e.operationID
+			}
+			return
+		}
+
 		// Error is the implementation of the error interface.
 		func (e *Error) Error() string {
-			if e.reason != nil {
-				return *e.reason
+			chunks := make([]string, 0, 3)
+			if e.id != nil && *e.id != "" {
+				chunks = append(chunks, fmt.Sprintf("identifier is '%s'", *e.id))
 			}
-			if e.code != nil {
-				return *e.code
+			if e.code != nil && *e.code != "" {
+				chunks = append(chunks, fmt.Sprintf("code is '%s'", *e.code))
 			}
-			if e.id != nil {
-				return *e.id
+			if e.operationID != nil && *e.operationID != "" {
+				chunks = append(chunks, fmt.Sprintf("operation identifier is '%s'", *e.operationID))
+			}
+			var result string
+			size := len(chunks)
+			if size == 1 {
+				result = chunks[0]
+			} else if size > 1 {
+				result = strings.Join(chunks[0:size-1], ", ") + " and " + chunks[size-1]
 			}
-			return "unknown error"
+			if e.reason != nil && *e.reason != "" {
+				if result != "" {
+					result = result + ": "
+				}
+				result = result + *e.reason
+			}
+			if result == "" {
+				result = "unknown error"
+			}
+			return result
 		}
 
-		// UnmarshalError reads an error from the given which can be an slice of bytes, a
-		// string, a reader or a JSON decoder.
+		// UnmarshalError reads an error from the given source which can be an slice of
+		// bytes, a string, a reader or a JSON decoder.
 		func UnmarshalError(source interface{}) (object *Error, err error) {
 			iterator, err := helpers.NewIterator(source)
 			if err != nil {
@@ -364,6 +411,9 @@ func (g *ErrorsGenerator) generateCommonErrors() error {
 				case "reason":
 					value := iterator.ReadString()
 					object.reason = &value
+				case "operation_id":
+					value := iterator.ReadString()
+					object.operationID = &value
 				default:
 					iterator.ReadAny()
 				}
@@ -403,6 +453,11 @@ func (g *ErrorsGenerator) generateCommonErrors() error {
 				stream.WriteObjectField("reason")
 				stream.WriteString(*e.reason)
 			}
+			if e.operationID != nil {
+				stream.WriteMore()
+				stream.WriteObjectField("operation_id")
+				stream.WriteString(*e.operationID)
+			}
 			stream.WriteObjectEnd()
 		}
 

tests/go/builders_test.go

@@ -24,6 +24,7 @@ import (
 
 	amv1 "github.com/openshift-online/ocm-api-metamodel/tests/go/generated/accountsmgmt/v1"
 	cmv1 "github.com/openshift-online/ocm-api-metamodel/tests/go/generated/clustersmgmt/v1"
+	"github.com/openshift-online/ocm-api-metamodel/tests/go/generated/errors"
 )
 
 var _ = Describe("Builder", func() {
@@ -202,6 +203,22 @@ var _ = Describe("Builder", func() {
 			Expect(second.Username()).To(Equal("youruser"))
 			Expect(second.Email()).To(Equal("yourmail"))
 		})
+
+		It("Can build an error", func() {
+			object, err := errors.NewError().
+				ID("401").
+				HREF("/api/clusters_mgmt/v1/errors/401").
+				Code("CLUSTERS-MGMT-401").
+				Reason("My reason").
+				OperationID("456").
+				Build()
+			Expect(err).ToNot(HaveOccurred())
+			Expect(object.ID()).To(Equal("401"))
+			Expect(object.HREF()).To(Equal("/api/clusters_mgmt/v1/errors/401"))
+			Expect(object.Code()).To(Equal("CLUSTERS-MGMT-401"))
+			Expect(object.Reason()).To(Equal("My reason"))
+			Expect(object.OperationID()).To(Equal("456"))
+		})
 	})
 
 	Describe("Copy", func() {

tests/go/errors_test.go

@@ -0,0 +1,102 @@
+/*
+Copyright (c) 2020 Red Hat, Inc.
+
+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.
+*/
+
+// This file contains tests for errors.
+
+package tests
+
+import (
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/ginkgo/extensions/table"
+	. "github.com/onsi/gomega"
+
+	"github.com/openshift-online/ocm-api-metamodel/tests/go/generated/errors"
+)
+
+var _ = FDescribe("Errors", func() {
+	DescribeTable(
+		"Conversion to string",
+		func(input, expected string) {
+			object, err := errors.UnmarshalError(input)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(object).ToNot(BeNil())
+			actual := object.Error()
+			Expect(actual).To(Equal(expected))
+		},
+		Entry(
+			"Empty",
+			`{}`,
+			"unknown error",
+		),
+		Entry(
+			"Only identifier",
+			`{
+				"id": "401"
+			}`,
+			"identifier is '401'",
+		),
+		Entry(
+			"Only code",
+			`{
+				"code": "CLUSTERS-MGMT-401"
+			}`,
+			"code is 'CLUSTERS-MGMT-401'",
+		),
+		Entry(
+			"Only operation identifier",
+			`{
+				"operation_id": "456"
+			}`,
+			"operation identifier is '456'",
+		),
+		Entry(
+			"Only reason",
+			`{
+				"reason": "My reason"
+			}`,
+			`My reason`,
+		),
+		Entry(
+			"Identifier and code",
+			`{
+				"id": "401",
+				"code": "CLUSTERS-MGMT-401"
+			}`,
+			"identifier is '401' and code is 'CLUSTERS-MGMT-401'",
+		),
+		Entry(
+			"Identifier, code and operation identifier",
+			`{
+				"id": "401",
+				"code": "CLUSTERS-MGMT-401",
+				"operation_id": "456"
+			}`,
+			"identifier is '401', code is 'CLUSTERS-MGMT-401' and operation "+
+				"identifier is '456'",
+		),
+		Entry(
+			"Identifier, code, operation identifier and reason",
+			`{
+				"id": "401",
+				"code": "CLUSTERS-MGMT-401",
+				"reason": "My reason",
+				"operation_id": "456"
+			}`,
+			"identifier is '401', code is 'CLUSTERS-MGMT-401' and operation "+
+				"identifier is '456': My reason",
+		),
+	)
+})

tests/go/marshal_test.go

@@ -177,6 +177,7 @@ var _ = Describe("Marshal", func() {
 			HREF("/api/clusters_mgmt/v1/errors/401").
 			Code("CLUSTERS-MGMT-401").
 			Reason("My reason").
+			OperationID("456").
 			Build()
 		Expect(err).ToNot(HaveOccurred())
 		buffer := new(bytes.Buffer)
@@ -187,7 +188,8 @@ var _ = Describe("Marshal", func() {
 			"id": "401",
 			"href": "/api/clusters_mgmt/v1/errors/401",
 			"code": "CLUSTERS-MGMT-401",
-			"reason": "My reason"
+			"reason": "My reason",
+			"operation_id": "456"
 		}`))
 	})
 

tests/go/unmarshal_test.go

@@ -469,7 +469,8 @@ var _ = Describe("Unmarshal", func() {
 			"id": "401",
 			"href": "/api/clusters_mgmt/v1/errors/401",
 			"code": "CLUSTERS-MGMT-401",
-			"reason": "My reason"
+			"reason": "My reason",
+			"operation_id": "456"
 		}`)
 		Expect(err).ToNot(HaveOccurred())
 		Expect(object).ToNot(BeNil())
@@ -478,6 +479,7 @@ var _ = Describe("Unmarshal", func() {
 		Expect(object.HREF()).To(Equal("/api/clusters_mgmt/v1/errors/401"))
 		Expect(object.Code()).To(Equal("CLUSTERS-MGMT-401"))
 		Expect(object.Reason()).To(Equal("My reason"))
+		Expect(object.OperationID()).To(Equal("456"))
 	})
 
 	It("Can read mixed known and unknown attributes", func() {