Add validation for Diff struct

Depfile

@@ -8,4 +8,7 @@ go:
     version: "v1.10.1"
   golangci-lint:
     importPath: "github.com/golangci/golangci-lint/cmd/golangci-lint"
-    version: "v1.53.3"
+    version: "v1.54.1"
+  mockgen:
+    importPath: github.com/golang/mock/mockgen
+    version: "v1.6.0"

cache/cache.go

@@ -4,6 +4,7 @@ import (
 	"sync"
 
 	"github.com/aserto-dev/azm/model"
+	"github.com/aserto-dev/azm/model/diff"
 )
 
 type Cache struct {
@@ -27,6 +28,13 @@ func (c *Cache) UpdateModel(m *model.Model) error {
 	return nil
 }
 
+// Returns a diff struct resulted between the old and the new model.
+func (c *Cache) Diff(other *model.Model) *diff.Diff {
+	c.mtx.Lock()
+	defer c.mtx.Unlock()
+	return c.model.Diff(other)
+}
+
 // ObjectExists, checks if given object type name exists in the model cache.
 func (c *Cache) ObjectExists(on model.ObjectName) bool {
 	c.mtx.RLock()

go.mod

@@ -7,6 +7,8 @@ require (
 	github.com/aserto-dev/errors v0.0.6
 	github.com/aserto-dev/go-aserto v0.20.4
 	github.com/aserto-dev/go-directory v0.30.0
+	github.com/golang/mock v1.1.1
+	github.com/hashicorp/go-multierror v1.1.1
 	github.com/magefile/mage v1.15.0
 	github.com/nsf/jsondiff v0.0.0-20230430225905-43f6cf3098c1
 	github.com/pkg/errors v0.9.1
@@ -26,6 +28,7 @@ require (
 	github.com/google/uuid v1.3.1 // indirect
 	github.com/grpc-ecosystem/grpc-gateway v1.16.0 // indirect
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.18.0 // indirect
+	github.com/hashicorp/errwrap v1.0.0 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect
 	github.com/mattn/go-isatty v0.0.19 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect

go.sum

@@ -28,6 +28,7 @@ github.com/ghodss/yaml v1.0.0/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeME
 github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
 github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
 github.com/golang/glog v1.1.2 h1:DVjP2PbBOzHyzA+dn3WhHIq4NdVu3Q+pvivFICf/7fo=
+github.com/golang/mock v1.1.1 h1:G5FRp8JnTd7RQH5kemVNlMeyXQAztQ3mOWV95KxsXH8=
 github.com/golang/mock v1.1.1/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/golang/protobuf v1.3.2/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
@@ -46,6 +47,10 @@ github.com/grpc-ecosystem/grpc-gateway v1.16.0 h1:gmcG1KaJ57LophUzW0Hy8NmPhnMZb4
 github.com/grpc-ecosystem/grpc-gateway v1.16.0/go.mod h1:BDjrQk3hbvj6Nolgz8mAMFbcEtjT1g+wF4CSlocrBnw=
 github.com/grpc-ecosystem/grpc-gateway/v2 v2.18.0 h1:RtRsiaGvWxcwd8y3BiRZxsylPT8hLWZ5SPcfI+3IDNk=
 github.com/grpc-ecosystem/grpc-gateway/v2 v2.18.0/go.mod h1:TzP6duP4Py2pHLVPPQp42aoYI92+PCrVotyR5e8Vqlk=
+github.com/hashicorp/errwrap v1.0.0 h1:hLrqtEDnRye3+sgx6z4qVLNuviH3MR5aQ0ykNJa/UYA=
+github.com/hashicorp/errwrap v1.0.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
+github.com/hashicorp/go-multierror v1.1.1 h1:H5DkEtf6CXdFp0N0Em5UCwQpXMWke8IA0+lD48awMYo=
+github.com/hashicorp/go-multierror v1.1.1/go.mod h1:iw975J/qwKPdAO1clOe2L8331t/9/fmwbPZ6JB6eMoM=
 github.com/hexops/gotextdiff v1.0.3 h1:gitA9+qJrrTCsiCl7+kh75nPqQt1cx4ZkudSTLoUqJM=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=

magefiles/magefile.go

@@ -39,3 +39,8 @@ func Test() error {
 func Deps() {
 	deps.GetAllDeps()
 }
+
+// Generate generates all code.
+func Generate() error {
+	return common.Generate()
+}

model/diff/diff.go

@@ -0,0 +1,101 @@
+package diff
+
+import (
+	"github.com/aserto-dev/go-directory/pkg/derr"
+	"github.com/hashicorp/go-multierror"
+	"github.com/pkg/errors"
+	"github.com/samber/lo"
+)
+
+//go:generate go run github.com/golang/mock/mockgen -destination=mock_instances.go  -package=diff github.com/aserto-dev/azm/model/diff Instances
+
+type Diff struct {
+	Added   Changes
+	Removed Changes
+}
+
+type Changes struct {
+	Objects   []string
+	Relations map[string][]string
+}
+
+// Only the types of the relation instances are needed.
+type RelationKind struct {
+	Object          string
+	Relation        string
+	Subject         string
+	SubjectRelation string
+}
+
+type Instances interface {
+	ObjectTypes() ([]string, error)
+	RelationTypes() ([]*RelationKind, error)
+}
+
+func (d *Diff) Validate(dv Instances) error {
+	var errs error
+	var rels []*RelationKind
+	if len(d.Removed.Objects) > 0 {
+		objs, err := dv.ObjectTypes()
+		if err != nil {
+			return err
+		}
+
+		rels, err = dv.RelationTypes()
+		if err != nil {
+			return err
+		}
+
+		err = d.validateObjectTypes(objs, rels)
+		errs = multierror.Append(errs, err)
+	}
+
+	if len(d.Removed.Relations) > 0 {
+		var err error
+		if len(rels) == 0 {
+			rels, err = dv.RelationTypes()
+			if err != nil {
+				return err
+			}
+
+		}
+		err = d.validateRelationsTypes(rels)
+		errs = multierror.Append(errs, err)
+	}
+
+	if merr, ok := errs.(*multierror.Error); ok && len(merr.Errors) > 0 {
+		return errs
+	}
+
+	return nil
+}
+
+func (d *Diff) validateObjectTypes(objs []string, rels []*RelationKind) error {
+	var errs error
+	for _, objType := range d.Removed.Objects {
+		_, found := lo.Find(objs, func(obj string) bool { return obj == objType })
+		if found {
+			errs = multierror.Append(errs, errors.Wrapf(derr.ErrObjectTypeInUse, "object type [%s]", objType))
+		}
+		rel, found := lo.Find(rels, func(rel *RelationKind) bool { return rel.Object == objType || rel.Subject == objType })
+		if found {
+			errs = multierror.Append(errs, errors.Wrapf(derr.ErrRelationTypeInUse, "object type [%s], relation type [%s]", objType, rel.Relation))
+		}
+	}
+	return errs
+}
+
+func (d *Diff) validateRelationsTypes(relations []*RelationKind) error {
+	var errs error
+	for objType, rels := range d.Removed.Relations {
+		for _, rel := range rels {
+			_, found := lo.Find(relations, func(rl *RelationKind) bool {
+				return (rl.Object == objType && rl.Relation == rel) || (rl.Subject == objType && rl.SubjectRelation == rel)
+			})
+			if found {
+				errs = multierror.Append(errs, errors.Wrapf(derr.ErrRelationTypeInUse, "object type [%s], relation type [%s]", objType, rel))
+			}
+		}
+	}
+	return errs
+}

model/diff/diff_test.go

@@ -0,0 +1,83 @@
+package diff_test
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/aserto-dev/azm/model/diff"
+	"github.com/aserto-dev/go-directory/pkg/derr"
+	gomock "github.com/golang/mock/gomock"
+	"github.com/stretchr/testify/require"
+)
+
+var ErrBoom = errors.New("Boom")
+
+func TestValidateDiffNoDeletion(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	mockInstances := diff.NewMockInstances(ctrl)
+
+	dif := diff.Diff{Removed: diff.Changes{}, Added: diff.Changes{}}
+	err := dif.Validate(mockInstances)
+
+	require.NoError(t, err)
+}
+
+func TestValidateDiffWithObjectTypeDeletion(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	mockInstances := diff.NewMockInstances(ctrl)
+	objType := "user"
+
+	dif := diff.Diff{Removed: diff.Changes{Objects: []string{objType}}, Added: diff.Changes{}}
+
+	mockInstances.EXPECT().ObjectTypes().Return([]string{}, nil)
+	mockInstances.EXPECT().RelationTypes().Return([]*diff.RelationKind{}, nil)
+	err := dif.Validate(mockInstances)
+
+	require.NoError(t, err)
+}
+
+func TestValidateDiffWith2ObjectTypeDeletion(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	mockInstances := diff.NewMockInstances(ctrl)
+	objTypes := []string{"user", "member"}
+
+	dif := diff.Diff{Removed: diff.Changes{Objects: objTypes}, Added: diff.Changes{}}
+
+	mockInstances.EXPECT().ObjectTypes().Return([]string{"user"}, nil)
+	mockInstances.EXPECT().RelationTypes().Return([]*diff.RelationKind{}, nil)
+	err := dif.Validate(mockInstances)
+
+	require.Error(t, err)
+	require.Contains(t, err.Error(), derr.ErrObjectTypeInUse.Message)
+}
+
+func TestValidateDiffWithRelationTypeDeletion(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	mockInstances := diff.NewMockInstances(ctrl)
+	objTypes := []string{"user", "member"}
+	relationTypes := map[string][]string{"folder": {"parent_folder"}}
+
+	dif := diff.Diff{Removed: diff.Changes{Objects: objTypes, Relations: relationTypes}, Added: diff.Changes{}}
+
+	mockInstances.EXPECT().ObjectTypes().Return([]string{}, nil)
+	mockInstances.EXPECT().RelationTypes().Return([]*diff.RelationKind{{Object: "folder", Relation: "parent_folder"}}, nil)
+	err := dif.Validate(mockInstances)
+
+	require.Error(t, err)
+	require.Contains(t, err.Error(), derr.ErrRelationTypeInUse.Message)
+}
+
+func TestValidateDiffWithObjectInstances(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	mockInstances := diff.NewMockInstances(ctrl)
+	objTypes := []string{"user", "member"}
+	relationTypes := map[string][]string{"folder": {"parent_folder"}}
+
+	dif := diff.Diff{Removed: diff.Changes{Objects: objTypes, Relations: relationTypes}, Added: diff.Changes{}}
+
+	mockInstances.EXPECT().ObjectTypes().Return([]string{}, ErrBoom)
+	err := dif.Validate(mockInstances)
+
+	require.Error(t, err)
+	require.Contains(t, err.Error(), ErrBoom.Error())
+}