add canSkipItemFailure handler func

adds a new func to the exchange backup handler: canskipItemFailure.
This interface allows any handler to evaluate the provided error and runtime
config to decide whether that error is able to be marked as skipped instead
of return a recoverable error as per standard.

src/internal/m365/collection/exchange/backup_test.go

@@ -88,6 +88,15 @@ func (bh mockBackupHandler) folderGetter() containerGetter             { return
 func (bh mockBackupHandler) previewIncludeContainers() []string        { return bh.previewIncludes }
 func (bh mockBackupHandler) previewExcludeContainers() []string        { return bh.previewExcludes }
 
+func (bh mockBackupHandler) CanSkipItemFailure(
+	error,
+	string,
+	string,
+	control.Options,
+) (fault.SkipCause, bool) {
+	return "", false
+}
+
 func (bh mockBackupHandler) NewContainerCache(
 	userID string,
 ) (string, graph.ContainerResolver) {

src/internal/m365/collection/exchange/contacts_backup.go

@@ -1,6 +1,8 @@
 package exchange
 
 import (
+	"github.com/alcionai/corso/src/pkg/control"
+	"github.com/alcionai/corso/src/pkg/fault"
 	"github.com/alcionai/corso/src/pkg/services/m365/api"
 	"github.com/alcionai/corso/src/pkg/services/m365/api/graph"
 )
@@ -52,3 +54,11 @@ func (h contactBackupHandler) NewContainerCache(
 		getter: h.ac,
 	}
 }
+
+func (h contactBackupHandler) CanSkipItemFailure(
+	error,
+	string, string,
+	control.Options,
+) (fault.SkipCause, bool) {
+	return "", false
+}

src/internal/m365/collection/exchange/contacts_backup_test.go

@@ -0,0 +1,31 @@
+package exchange
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/suite"
+
+	"github.com/alcionai/corso/src/internal/tester"
+	"github.com/alcionai/corso/src/pkg/control"
+	"github.com/alcionai/corso/src/pkg/fault"
+	"github.com/alcionai/corso/src/pkg/services/m365/api"
+)
+
+type ContactsBackupHandlerUnitSuite struct {
+	tester.Suite
+}
+
+func TestContactsBackupHandlerUnitSuite(t *testing.T) {
+	suite.Run(t, &ContactsBackupHandlerUnitSuite{Suite: tester.NewUnitSuite(t)})
+}
+
+func (suite *ContactsBackupHandlerUnitSuite) TestHandler_CanSkipItemFailure() {
+	t := suite.T()
+
+	h := newContactBackupHandler(api.Client{})
+	cause, result := h.CanSkipItemFailure(nil, "", "", control.Options{})
+
+	assert.False(t, result)
+	assert.Equal(t, fault.SkipCause(""), cause)
+}

src/internal/m365/collection/exchange/events_backup.go

@@ -1,6 +1,12 @@
 package exchange
 
 import (
+	"errors"
+	"slices"
+
+	"github.com/alcionai/clues"
+	"github.com/alcionai/corso/src/pkg/control"
+	"github.com/alcionai/corso/src/pkg/fault"
 	"github.com/alcionai/corso/src/pkg/services/m365/api"
 	"github.com/alcionai/corso/src/pkg/services/m365/api/graph"
 )
@@ -52,3 +58,22 @@ func (h eventBackupHandler) NewContainerCache(
 		getter: h.ac,
 	}
 }
+
+func (h eventBackupHandler) CanSkipItemFailure(
+	err error,
+	resourceID, itemID string,
+	opts control.Options,
+) (fault.SkipCause, bool) {
+	// yes, this is intentionally a todo.  I'll get back to it.
+	if !errors.Is(err, clues.New("todo fix me")) {
+		return "", false
+	}
+
+	itemIDs, ok := opts.SkipTheseEventsOnInstance503[resourceID]
+	if !ok {
+		return "", false
+	}
+
+	// strict equals required here.  ids are case sensitive.
+	return fault.SkipKnownEventInstance503s, slices.Contains(itemIDs, itemID)
+}

src/internal/m365/collection/exchange/events_backup_test.go

@@ -0,0 +1,109 @@
+package exchange
+
+import (
+	"testing"
+
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/suite"
+
+	"github.com/alcionai/clues"
+	"github.com/alcionai/corso/src/internal/tester"
+	"github.com/alcionai/corso/src/pkg/control"
+	"github.com/alcionai/corso/src/pkg/fault"
+	"github.com/alcionai/corso/src/pkg/services/m365/api"
+)
+
+type EventsBackupHandlerUnitSuite struct {
+	tester.Suite
+}
+
+func TestEventsBackupHandlerUnitSuite(t *testing.T) {
+	suite.Run(t, &EventsBackupHandlerUnitSuite{Suite: tester.NewUnitSuite(t)})
+}
+
+func (suite *EventsBackupHandlerUnitSuite) TestHandler_CanSkipItemFailure() {
+	var (
+		resourceID = uuid.NewString()
+		itemID     = uuid.NewString()
+	)
+
+	table := []struct {
+		name        string
+		err         error
+		opts        control.Options
+		expect      assert.BoolAssertionFunc
+		expectCause fault.SkipCause
+	}{
+		{
+			name:   "no config",
+			err:    nil,
+			opts:   control.Options{},
+			expect: assert.False,
+		},
+		{
+			name: "empty skip on 503",
+			err:  nil,
+			opts: control.Options{
+				SkipTheseEventsOnInstance503: map[string][]string{},
+			},
+			expect: assert.False,
+		},
+		{
+			name: "nil error",
+			err:  nil,
+			opts: control.Options{
+				SkipTheseEventsOnInstance503: map[string][]string{
+					"foo": []string{"bar", "baz"},
+				},
+			},
+			expect: assert.False,
+		},
+		{
+			name: "non-matching resource",
+			err:  clues.New("fix me I'm wrong"),
+			opts: control.Options{
+				SkipTheseEventsOnInstance503: map[string][]string{
+					"foo": []string{"bar", "baz"},
+				},
+			},
+			expect: assert.False,
+		},
+		{
+			name: "non-matching item",
+			err:  clues.New("fix me I'm wrong"),
+			opts: control.Options{
+				SkipTheseEventsOnInstance503: map[string][]string{
+					resourceID: []string{"bar", "baz"},
+				},
+			},
+			expect: assert.False,
+		},
+		{
+			name: "match on instance 503",
+			err:  clues.New("fix me I'm wrong"),
+			opts: control.Options{
+				SkipTheseEventsOnInstance503: map[string][]string{
+					resourceID: []string{"bar", itemID},
+				},
+			},
+			expect:      assert.True,
+			expectCause: fault.SkipKnownEventInstance503s,
+		},
+	}
+	for _, test := range table {
+		suite.Run(test.name, func() {
+			t := suite.T()
+
+			h := newEventBackupHandler(api.Client{})
+			cause, result := h.CanSkipItemFailure(
+				test.err,
+				resourceID,
+				itemID,
+				test.opts)
+
+			test.expect(t, result)
+			assert.Equal(t, test.expectCause, cause)
+		})
+	}
+}

src/internal/m365/collection/exchange/handlers.go

@@ -26,6 +26,8 @@ type backupHandler interface {
 	previewIncludeContainers() []string
 	previewExcludeContainers() []string
 	NewContainerCache(userID string) (string, graph.ContainerResolver)
+
+	canSkipItemFailurer
 }
 
 type addedAndRemovedItemGetter interface {
@@ -57,6 +59,14 @@ func BackupHandlers(ac api.Client) map[path.CategoryType]backupHandler {
 	}
 }
 
+type canSkipItemFailurer interface {
+	CanSkipItemFailure(
+		err error,
+		resourceID, itemID string,
+		opts control.Options,
+	) (fault.SkipCause, bool)
+}
+
 // ---------------------------------------------------------------------------
 // restore
 // ---------------------------------------------------------------------------

src/internal/m365/collection/exchange/mail_backup.go

@@ -1,6 +1,8 @@
 package exchange
 
 import (
+	"github.com/alcionai/corso/src/pkg/control"
+	"github.com/alcionai/corso/src/pkg/fault"
 	"github.com/alcionai/corso/src/pkg/services/m365/api"
 	"github.com/alcionai/corso/src/pkg/services/m365/api/graph"
 )
@@ -57,3 +59,11 @@ func (h mailBackupHandler) NewContainerCache(
 		getter: h.ac,
 	}
 }
+
+func (h mailBackupHandler) CanSkipItemFailure(
+	error,
+	string, string,
+	control.Options,
+) (fault.SkipCause, bool) {
+	return "", false
+}

src/internal/m365/collection/exchange/mail_backup_test.go

@@ -0,0 +1,31 @@
+package exchange
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/suite"
+
+	"github.com/alcionai/corso/src/internal/tester"
+	"github.com/alcionai/corso/src/pkg/control"
+	"github.com/alcionai/corso/src/pkg/fault"
+	"github.com/alcionai/corso/src/pkg/services/m365/api"
+)
+
+type MailBackupHandlerUnitSuite struct {
+	tester.Suite
+}
+
+func TestMailBackupHandlerUnitSuite(t *testing.T) {
+	suite.Run(t, &MailBackupHandlerUnitSuite{Suite: tester.NewUnitSuite(t)})
+}
+
+func (suite *MailBackupHandlerUnitSuite) TestHandler_CanSkipItemFailure() {
+	t := suite.T()
+
+	h := newMailBackupHandler(api.Client{})
+	cause, result := h.CanSkipItemFailure(nil, "", "", control.Options{})
+
+	assert.False(t, result)
+	assert.Equal(t, fault.SkipCause(""), cause)
+}