ByTextReference accepts many references (sourcegraph#52247)

Part of
[sourcegraph#52133](https://github.com/sourcegraph/sourcegraph/issues/52133)

This pull request extends the Bag to take in many references at once.
This is used for search (see sourcegraph#52219) where many ownership terms are
given to include and exclude for search.

## Test plan

Small test to verify a multi-bag works.

enterprise/internal/own/ownref.go

@@ -87,15 +87,28 @@ type Bag interface {
 // This can be used in search to find relevant owners by different identifiers
 // that the database reveals.
 // TODO(#52141): Search by code host handle.
-func ByTextReference(ctx context.Context, db edb.EnterpriseDB, text string) (Bag, error) {
-	text = strings.TrimPrefix(text, "@")
-	if _, err := mail.ParseAddress(text); err == nil {
-		return ByEmailReference(ctx, db, text)
+// TODO(#52246): ByTextReference uses fewer queries.
+func ByTextReference(ctx context.Context, db edb.EnterpriseDB, text ...string) (Bag, error) {
+	var multiBag bag
+	for _, t := range text {
+		t = strings.TrimPrefix(t, "@")
+		if _, err := mail.ParseAddress(t); err == nil {
+			b, err := ByEmailReference(ctx, db, t)
+			if err != nil {
+				return nil, err
+			}
+			multiBag = append(multiBag, b...)
+		}
+		b, err := ByUserHandleReference(ctx, db, t)
+		if err != nil {
+			return nil, err
+		}
+		multiBag = append(multiBag, b...)
 	}
-	return ByUserHandleReference(ctx, db, text)
+	return multiBag, nil
 }
 
-func ByUserHandleReference(ctx context.Context, db edb.EnterpriseDB, handle string) (Bag, error) {
+func ByUserHandleReference(ctx context.Context, db edb.EnterpriseDB, handle string) (bag, error) {
 	var b bag
 	// Try to find a user by username.
 	user, err := db.Users().GetByUsername(ctx, handle)
@@ -115,7 +128,7 @@ func ByUserHandleReference(ctx context.Context, db edb.EnterpriseDB, handle stri
 	return hydrateWithVerifiedEmails(ctx, db, b)
 }
 
-func hydrateWithVerifiedEmails(ctx context.Context, db edb.EnterpriseDB, b bag) (Bag, error) {
+func hydrateWithVerifiedEmails(ctx context.Context, db edb.EnterpriseDB, b bag) (bag, error) {
 	for _, userRefs := range b {
 		if userRefs.id == 0 {
 			continue
@@ -132,7 +145,7 @@ func hydrateWithVerifiedEmails(ctx context.Context, db edb.EnterpriseDB, b bag)
 	return b, nil
 }
 
-func ByEmailReference(ctx context.Context, db edb.EnterpriseDB, email string) (Bag, error) {
+func ByEmailReference(ctx context.Context, db edb.EnterpriseDB, email string) (bag, error) {
 	var b bag
 	// Checking that provided email is verified.
 	verifiedEmails, err := db.UserEmails().GetVerifiedEmails(ctx, email)

enterprise/internal/own/ownref_test.go

@@ -285,8 +285,33 @@ func TestBagUnverifiedEmailOnlyMatchesWithItself(t *testing.T) {
 				assert.True(t, bag.Contains(r), fmt.Sprintf("bag.Contains(%s), want true, got false", r))
 			} else {
 				assert.False(t, bag.Contains(r), fmt.Sprintf("bag.Contains(%s), want false, got true", r))
-
 			}
 		})
 	}
 }
+
+func TestBagManyUsers(t *testing.T) {
+	if testing.Short() {
+		t.Skip()
+	}
+	t.Parallel()
+	logger := logtest.Scoped(t)
+	db := edb.NewEnterpriseDB(database.NewDB(logger, dbtest.NewDB(logger, t)))
+	ctx := context.Background()
+	_, err := db.Users().Create(ctx, database.NewUser{
+		Email:           "[email protected]",
+		Username:        "jdoe",
+		EmailIsVerified: true,
+	})
+	require.NoError(t, err)
+	_, err = db.Users().Create(ctx, database.NewUser{
+		Email:           "[email protected]",
+		Username:        "ssmith",
+		EmailIsVerified: true,
+	})
+	require.NoError(t, err)
+	bag, err := ByTextReference(ctx, db, "jdoe", "ssmith")
+	require.NoError(t, err)
+	assert.True(t, bag.Contains(Reference{Handle: "ssmith"}))
+	assert.True(t, bag.Contains(Reference{Handle: "jdoe"}))
+}