deprecate adder interface for only fault.Errors (#2378)

## Does this PR need a docs update or release note?

- [x] ⛔ No 

## Type of change

- [x] 🧹 Tech Debt/Cleanup

## Issue(s)

* #1970

## Test Plan

- [x] ⚡ Unit test
- [x] 💚 E2E

src/internal/operations/manifests.go

@@ -135,13 +135,17 @@ func produceManifestsAndMetadata(
 // of manifests, that each manifest's Reason (owner, service, category) is only
 // included once.  If a reason is duplicated by any two manifests, an error is
 // returned.
-func verifyDistinctBases(ctx context.Context, mans []*kopia.ManifestEntry, errs fault.Adder) error {
+func verifyDistinctBases(ctx context.Context, mans []*kopia.ManifestEntry, errs *fault.Errors) error {
 	var (
 		failed  bool
 		reasons = map[string]manifest.ID{}
 	)
 
 	for _, man := range mans {
+		if errs.Failed() {
+			break
+		}
+
 		// Incomplete snapshots are used only for kopia-assisted incrementals. The
 		// fact that we need this check here makes it seem like this should live in
 		// the kopia code. However, keeping it here allows for better debugging as
@@ -173,7 +177,7 @@ func verifyDistinctBases(ctx context.Context, mans []*kopia.ManifestEntry, errs
 		return clues.New("multiple base snapshots qualify").WithClues(ctx)
 	}
 
-	return nil
+	return errs.Err()
 }
 
 // collectMetadata retrieves all metadata files associated with the manifest.

src/internal/operations/manifests_test.go

@@ -15,7 +15,6 @@ import (
 	"github.com/alcionai/corso/src/internal/tester"
 	"github.com/alcionai/corso/src/pkg/backup"
 	"github.com/alcionai/corso/src/pkg/fault"
-	"github.com/alcionai/corso/src/pkg/fault/mock"
 	"github.com/alcionai/corso/src/pkg/path"
 )
 
@@ -392,7 +391,7 @@ func (suite *OperationsManifestsUnitSuite) TestVerifyDistinctBases() {
 			ctx, flush := tester.NewContext()
 			defer flush()
 
-			err := verifyDistinctBases(ctx, test.mans, mock.NewAdder())
+			err := verifyDistinctBases(ctx, test.mans, fault.New(true))
 			test.expect(t, err)
 		})
 	}
@@ -834,7 +833,7 @@ func (suite *BackupManifestSuite) TestBackupOperation_VerifyDistinctBases() {
 			ctx, flush := tester.NewContext()
 			defer flush()
 
-			test.errCheck(t, verifyDistinctBases(ctx, test.input, mock.NewAdder()))
+			test.errCheck(t, verifyDistinctBases(ctx, test.input, fault.New(true)))
 		})
 	}
 }

src/pkg/fault/fault.go

@@ -102,11 +102,6 @@ func (e *Errors) setErr(err error) *Errors {
 	return e
 }
 
-type Adder interface {
-	Add(err error) *Errors
-	Failed() bool
-}
-
 // Add appends the error to the slice of recoverable and
 // iterated errors (ie: errors.errs).  If failFast is true,
 // the first Added error will get copied to errors.err,

src/pkg/fault/mock/mock.go

@@ -1,22 +0,0 @@
-package mock
-
-import "github.com/alcionai/corso/src/pkg/fault"
-
-// Adder mocks an adder interface for testing.
-type Adder struct {
-	FailFast bool
-	Errs     []error
-}
-
-func NewAdder() *Adder {
-	return &Adder{Errs: []error{}}
-}
-
-func (ma *Adder) Add(err error) *fault.Errors {
-	ma.Errs = append(ma.Errs, err)
-	return fault.New(true)
-}
-
-func (ma *Adder) Failed() bool {
-	return ma.FailFast && len(ma.Errs) > 0
-}

src/pkg/selectors/exchange.go

@@ -708,7 +708,7 @@ func (s ExchangeScope) setDefaults() {
 func (s exchange) Reduce(
 	ctx context.Context,
 	deets *details.Details,
-	errs fault.Adder,
+	errs *fault.Errors,
 ) *details.Details {
 	return reduce[ExchangeScope](
 		ctx,

src/pkg/selectors/exchange_test.go

@@ -11,7 +11,7 @@ import (
 	"github.com/alcionai/corso/src/internal/common"
 	"github.com/alcionai/corso/src/internal/tester"
 	"github.com/alcionai/corso/src/pkg/backup/details"
-	"github.com/alcionai/corso/src/pkg/fault/mock"
+	"github.com/alcionai/corso/src/pkg/fault"
 	"github.com/alcionai/corso/src/pkg/filters"
 	"github.com/alcionai/corso/src/pkg/path"
 )
@@ -1030,13 +1030,10 @@ func (suite *ExchangeSelectorSuite) TestExchangeRestore_Reduce() {
 			ctx, flush := tester.NewContext()
 			defer flush()
 
-			errs := mock.NewAdder()
-
 			sel := test.makeSelector()
-			results := sel.Reduce(ctx, test.deets, errs)
+			results := sel.Reduce(ctx, test.deets, fault.New(true))
 			paths := results.Paths()
 			assert.Equal(t, test.expect, paths)
-			assert.Empty(t, errs.Errs)
 		})
 	}
 }

src/pkg/selectors/onedrive.go

@@ -487,7 +487,7 @@ func (s OneDriveScope) DiscreteCopy(user string) OneDriveScope {
 func (s oneDrive) Reduce(
 	ctx context.Context,
 	deets *details.Details,
-	errs fault.Adder,
+	errs *fault.Errors,
 ) *details.Details {
 	return reduce[OneDriveScope](
 		ctx,

src/pkg/selectors/onedrive_test.go

@@ -11,7 +11,7 @@ import (
 	"github.com/alcionai/corso/src/internal/common"
 	"github.com/alcionai/corso/src/internal/tester"
 	"github.com/alcionai/corso/src/pkg/backup/details"
-	"github.com/alcionai/corso/src/pkg/fault/mock"
+	"github.com/alcionai/corso/src/pkg/fault"
 	"github.com/alcionai/corso/src/pkg/path"
 )
 
@@ -242,13 +242,10 @@ func (suite *OneDriveSelectorSuite) TestOneDriveRestore_Reduce() {
 			ctx, flush := tester.NewContext()
 			defer flush()
 
-			errs := mock.NewAdder()
-
 			sel := test.makeSelector()
-			results := sel.Reduce(ctx, test.deets, errs)
+			results := sel.Reduce(ctx, test.deets, fault.New(true))
 			paths := results.Paths()
 			assert.Equal(t, test.expect, paths)
-			assert.Empty(t, errs.Errs)
 		})
 	}
 }

src/pkg/selectors/scopes.go

@@ -287,7 +287,7 @@ func reduce[T scopeT, C categoryT](
 	deets *details.Details,
 	s Selector,
 	dataCategories map[path.CategoryType]C,
-	errs fault.Adder,
+	errs *fault.Errors,
 ) *details.Details {
 	ctx, end := D.Span(ctx, "selectors:reduce")
 	defer end()

src/pkg/selectors/scopes_test.go

@@ -9,7 +9,7 @@ import (
 
 	"github.com/alcionai/corso/src/internal/tester"
 	"github.com/alcionai/corso/src/pkg/backup/details"
-	"github.com/alcionai/corso/src/pkg/fault/mock"
+	"github.com/alcionai/corso/src/pkg/fault"
 	"github.com/alcionai/corso/src/pkg/filters"
 	"github.com/alcionai/corso/src/pkg/path"
 )
@@ -274,7 +274,7 @@ func (suite *SelectorScopesSuite) TestReduce() {
 			ctx, flush := tester.NewContext()
 			defer flush()
 
-			errs := mock.NewAdder()
+			errs := fault.New(true)
 
 			ds := deets()
 			result := reduce[mockScope](
@@ -284,7 +284,7 @@ func (suite *SelectorScopesSuite) TestReduce() {
 				dataCats,
 				errs)
 			require.NotNil(t, result)
-			require.Empty(t, errs.Errs, "iteration errors")
+			require.Empty(t, errs.Errs(), "recoverable errors")
 			assert.Len(t, result.Entries, test.expectLen)
 		})
 	}

src/pkg/selectors/selectors.go

@@ -70,7 +70,7 @@ var (
 const All = "All"
 
 type Reducer interface {
-	Reduce(context.Context, *details.Details, fault.Adder) *details.Details
+	Reduce(context.Context, *details.Details, *fault.Errors) *details.Details
 }
 
 // selectorResourceOwners aggregates all discrete path category types described
@@ -240,7 +240,7 @@ func (s Selector) PathService() path.ServiceType {
 func (s Selector) Reduce(
 	ctx context.Context,
 	deets *details.Details,
-	errs fault.Adder,
+	errs *fault.Errors,
 ) (*details.Details, error) {
 	r, err := selectorAsIface[Reducer](s)
 	if err != nil {

src/pkg/selectors/selectors_reduce_test.go

@@ -10,7 +10,7 @@ import (
 	"github.com/alcionai/corso/src/internal/common"
 	"github.com/alcionai/corso/src/internal/tester"
 	"github.com/alcionai/corso/src/pkg/backup/details"
-	"github.com/alcionai/corso/src/pkg/fault/mock"
+	"github.com/alcionai/corso/src/pkg/fault"
 	"github.com/alcionai/corso/src/pkg/selectors"
 	"github.com/alcionai/corso/src/pkg/selectors/testdata"
 )
@@ -265,11 +265,8 @@ func (suite *SelectorReduceSuite) TestReduce() {
 
 	for _, test := range table {
 		suite.T().Run(test.name, func(t *testing.T) {
-			errs := mock.NewAdder()
+			output := test.selFunc().Reduce(ctx, allDetails, fault.New(true))
-
-			output := test.selFunc().Reduce(ctx, allDetails, errs)
 			assert.ElementsMatch(t, test.expected, output.Entries)
-			assert.Empty(t, errs.Errs)
 		})
 	}
 }

src/pkg/selectors/sharepoint.go

@@ -559,7 +559,7 @@ func (s SharePointScope) DiscreteCopy(site string) SharePointScope {
 func (s sharePoint) Reduce(
 	ctx context.Context,
 	deets *details.Details,
-	errs fault.Adder,
+	errs *fault.Errors,
 ) *details.Details {
 	return reduce[SharePointScope](
 		ctx,

src/pkg/selectors/sharepoint_test.go

@@ -9,7 +9,7 @@ import (
 
 	"github.com/alcionai/corso/src/internal/tester"
 	"github.com/alcionai/corso/src/pkg/backup/details"
-	"github.com/alcionai/corso/src/pkg/fault/mock"
+	"github.com/alcionai/corso/src/pkg/fault"
 	"github.com/alcionai/corso/src/pkg/path"
 )
 
@@ -306,13 +306,10 @@ func (suite *SharePointSelectorSuite) TestSharePointRestore_Reduce() {
 			ctx, flush := tester.NewContext()
 			defer flush()
 
-			errs := mock.NewAdder()
-
 			sel := test.makeSelector()
-			results := sel.Reduce(ctx, test.deets, errs)
+			results := sel.Reduce(ctx, test.deets, fault.New(true))
 			paths := results.Paths()
 			assert.Equal(t, test.expect, paths)
-			assert.Empty(t, errs.Errs)
 		})
 	}
 }