[feature] Add experimental `instance-federation-spam-filter` option (#2685)

* [chore] Move `visibility` to `filter/visibility`

* [feature] Add experimental instance-federation-spam-filter option

4 files changed, 1343 insertions, 0 deletions

diff --git a/internal/filter/spam/spam.go b/internal/filter/spam/spam.go
new file mode 100644
index 000000000..386c2719b
--- /dev/null
+++ b/internal/filter/spam/spam.go
@@ -0,0 +1,32 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package spam
+
+import "github.com/superseriousbusiness/gotosocial/internal/state"
+
+// Filter packages logic for checking whether
+// given statuses should be considered spam.
+type Filter struct {
+	state *state.State
+}
+
+// NewFilter returns a new spam Filter
+// that will use the provided state.
+func NewFilter(state *state.State) *Filter {
+	return &Filter{state: state}
+}
diff --git a/internal/filter/spam/spam_test.go b/internal/filter/spam/spam_test.go
new file mode 100644
index 000000000..d9d867a07
--- /dev/null
+++ b/internal/filter/spam/spam_test.go
@@ -0,0 +1,59 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package spam_test
+
+import (
+	"github.com/stretchr/testify/suite"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/filter/spam"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/state"
+	"github.com/superseriousbusiness/gotosocial/testrig"
+)
+
+type FilterStandardTestSuite struct {
+	// standard suite interfaces
+	suite.Suite
+	db    db.DB
+	state state.State
+
+	// standard suite models
+	testAccounts map[string]*gtsmodel.Account
+
+	filter *spam.Filter
+}
+
+func (suite *FilterStandardTestSuite) SetupSuite() {
+	suite.testAccounts = testrig.NewTestAccounts()
+}
+
+func (suite *FilterStandardTestSuite) SetupTest() {
+	suite.state.Caches.Init()
+
+	testrig.InitTestConfig()
+	testrig.InitTestLog()
+
+	suite.db = testrig.NewTestDB(&suite.state)
+	suite.filter = spam.NewFilter(&suite.state)
+
+	testrig.StandardDBSetup(suite.db, nil)
+}
+
+func (suite *FilterStandardTestSuite) TearDownTest() {
+	testrig.StandardDBTeardown(suite.db)
+}
diff --git a/internal/filter/spam/statusable.go b/internal/filter/spam/statusable.go
new file mode 100644
index 000000000..60598f920
--- /dev/null
+++ b/internal/filter/spam/statusable.go
@@ -0,0 +1,472 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package spam
+
+import (
+	"context"
+	"errors"
+	"net/url"
+	"slices"
+	"strings"
+
+	"github.com/miekg/dns"
+	"github.com/superseriousbusiness/gotosocial/internal/ap"
+	"github.com/superseriousbusiness/gotosocial/internal/config"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtscontext"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/log"
+	"github.com/superseriousbusiness/gotosocial/internal/regexes"
+	"github.com/superseriousbusiness/gotosocial/internal/util"
+)
+
+// preppedMention represents a partially-parsed
+// mention, prepared for spam checking purposes.
+type preppedMention struct {
+	*gtsmodel.Mention
+	uri    *url.URL
+	domain string
+	user   string
+	local  bool
+}
+
+// StatusableOK returns no error if the given statusable looks OK,
+// ie., relevant to the receiver, and not spam.
+//
+// This should only be used for Creates of statusables, NOT Announces!
+//
+// If the statusable does not pass relevancy or spam checks, either
+// a Spam or NotRelevant error will be returned. Callers should use
+// gtserror.IsSpam() and gtserror.IsNotRelevant() to check for this.
+//
+// If the returned error is not nil, but neither Spam or NotRelevant,
+// then it's an actual database error.
+//
+// The decision is made based on the following heuristics, in order:
+//
+//  1. Receiver follow requester. Return nil.
+//  2. Statusable doesn't mention receiver. Return NotRelevant.
+//
+// If instance-federation-spam-filter = false, then return nil now.
+// Otherwise check:
+//
+//  3. Receiver is locked and is followed by requester. Return nil.
+//  4. Five or more people are mentioned. Return Spam.
+//  5. Receiver follow (requests) a mentioned account. Return nil.
+//  6. Statusable has a media attachment. Return Spam.
+//  7. Statusable contains non-mention, non-hashtag links. Return Spam.
+func (f *Filter) StatusableOK(
+	ctx context.Context,
+	receiver *gtsmodel.Account,
+	requester *gtsmodel.Account,
+	statusable ap.Statusable,
+) error {
+	// HEURISTIC 1: Check whether receiving account follows the requesting account.
+	// If so, we know it's OK and don't need to do any other checks.
+	follows, err := f.state.DB.IsFollowing(ctx, receiver.ID, requester.ID)
+	if err != nil {
+		return gtserror.Newf("db error checking follow status: %w", err)
+	}
+
+	if follows {
+		// Looks fine.
+		return nil
+	}
+
+	// HEURISTIC 2: Check whether statusable mentions the
+	// receiver. If not, we don't want to process this message.
+	rawMentions, _ := ap.ExtractMentions(statusable)
+	mentions := prepMentions(ctx, rawMentions)
+	mentioned := f.isMentioned(ctx, receiver, mentions)
+	if !mentioned {
+		// This is a random message fired
+		// into our inbox, just drop it.
+		err := errors.New("receiver does not follow requester, and is not mentioned")
+		return gtserror.SetNotRelevant(err)
+	}
+
+	// Receiver is mentioned, but not by someone
+	// they follow. Check if we need to do more
+	// granular spam filtering.
+	if !config.GetInstanceFederationSpamFilter() {
+		// Filter is not enabled, allow it
+		// through without further checks.
+		return nil
+	}
+
+	// More granular spam filtering time!
+	//
+	// HEURISTIC 3: Does requester follow locked receiver?
+	followedBy, err := f.lockedFollowedBy(ctx, receiver, requester)
+	if err != nil {
+		return gtserror.Newf("db error checking follow status: %w", err)
+	}
+
+	// If receiver is locked, and is followed
+	// by requester, this likely means they're
+	// interested in the message. Allow it.
+	if followedBy {
+		return nil
+	}
+
+	// HEURISTIC 4: How many people are mentioned?
+	// If it's 5 or more we can assume this is spam.
+	mentionsLen := len(mentions)
+	if mentionsLen >= 5 {
+		err := errors.New("status mentions 5 or more people")
+		return gtserror.SetSpam(err)
+	}
+
+	// HEURISTIC 5: Four or fewer people are mentioned,
+	// do we follow (request) at least one of them?
+	// If so, we're probably interested in the message.
+	knowsOne := f.knowsOneMentioned(ctx, receiver, mentions)
+	if knowsOne {
+		return nil
+	}
+
+	// HEURISTIC 6: Are there any media attachments?
+	attachments, _ := ap.ExtractAttachments(statusable)
+	hasAttachments := len(attachments) != 0
+	if hasAttachments {
+		err := errors.New("status has attachment(s)")
+		return gtserror.SetSpam(err)
+	}
+
+	// HEURISTIC 7: Are there any links in the post
+	// aside from mentions and hashtags? Include the
+	// summary/content warning when checking.
+	hashtags, _ := ap.ExtractHashtags(statusable)
+	hasErrantLinks := f.errantLinks(ctx, statusable, mentions, hashtags)
+	if hasErrantLinks {
+		err := errors.New("status has one or more non-mention, non-hashtag links")
+		return gtserror.SetSpam(err)
+	}
+
+	// Looks OK.
+	return nil
+}
+
+// prepMentions prepares a slice of mentions
+// for spam checking by parsing out the namestring
+// and targetAccountURI values, if present.
+func prepMentions(
+	ctx context.Context,
+	mentions []*gtsmodel.Mention,
+) []preppedMention {
+	var (
+		host          = config.GetHost()
+		accountDomain = config.GetAccountDomain()
+	)
+
+	parsedMentions := make([]preppedMention, 0, len(mentions))
+	for _, mention := range mentions {
+		// Start by just embedding
+		// the original mention.
+		parsedMention := preppedMention{
+			Mention: mention,
+		}
+
+		// Try to parse namestring if present.
+		if mention.NameString != "" {
+			user, domain, err := util.ExtractNamestringParts(mention.NameString)
+			if err != nil {
+				// Malformed mention,
+				// just log + ignore.
+				log.Debugf(ctx,
+					"malformed mention namestring: %v",
+					err,
+				)
+				continue
+			}
+
+			parsedMention.domain = domain
+			parsedMention.user = user
+		}
+
+		// Try to parse URI if present.
+		if mention.TargetAccountURI != "" {
+			targetURI, err := url.Parse(mention.TargetAccountURI)
+			if err != nil {
+				// Malformed mention,
+				// just log + ignore.
+				log.Debugf(ctx,
+					"malformed mention uri: %v",
+					err,
+				)
+				continue
+			}
+
+			parsedMention.uri = targetURI
+
+			// Set host from targetURI if
+			// it wasn't set by namestring.
+			if parsedMention.domain == "" {
+				parsedMention.domain = targetURI.Host
+			}
+		}
+
+		// It's a mention of a local account if the target host is us.
+		parsedMention.local = parsedMention.domain == host || parsedMention.domain == accountDomain
+
+		// Done with this one.
+		parsedMentions = append(parsedMentions, parsedMention)
+	}
+
+	return parsedMentions
+}
+
+// isMentioned returns true if the
+// receiver is targeted by at least
+// one of the given mentions.
+func (f *Filter) isMentioned(
+	ctx context.Context,
+	receiver *gtsmodel.Account,
+	mentions []preppedMention,
+) bool {
+	return slices.ContainsFunc(
+		mentions,
+		func(mention preppedMention) bool {
+			// Check if receiver mentioned by URI.
+			if accURI := mention.TargetAccountURI; accURI != "" &&
+				(accURI == receiver.URI || accURI == receiver.URL) {
+				return true
+			}
+
+			// Check if receiver mentioned by namestring.
+			if mention.local && strings.EqualFold(mention.user, receiver.Username) {
+				return true
+			}
+
+			// Mention doesn't
+			// target receiver.
+			return false
+		},
+	)
+}
+
+// lockedFollowedBy returns true
+// if receiver account is locked,
+// and requester follows receiver.
+func (f *Filter) lockedFollowedBy(
+	ctx context.Context,
+	receiver *gtsmodel.Account,
+	requester *gtsmodel.Account,
+) (bool, error) {
+	// If receiver is not locked,
+	// return early to avoid a db call.
+	if !*receiver.Locked {
+		return false, nil
+	}
+
+	return f.state.DB.IsFollowing(ctx, requester.ID, receiver.ID)
+}
+
+// knowsOneMentioned returns true if the
+// receiver follows or has follow requested
+// at least one of the mentioned accounts.
+func (f *Filter) knowsOneMentioned(
+	ctx context.Context,
+	receiver *gtsmodel.Account,
+	mentions []preppedMention,
+) bool {
+	return slices.ContainsFunc(
+		mentions,
+		func(mention preppedMention) bool {
+			var (
+				acc *gtsmodel.Account
+				err error
+			)
+
+			// Try to get target account without
+			// dereffing. After all, if they're not
+			// in our db we definitely don't know them.
+			if mention.TargetAccountURI != "" {
+				acc, err = f.state.DB.GetAccountByURI(
+					gtscontext.SetBarebones(ctx),
+					mention.TargetAccountURI,
+				)
+			} else if mention.user != "" {
+				acc, err = f.state.DB.GetAccountByUsernameDomain(
+					gtscontext.SetBarebones(ctx),
+					mention.user,
+					mention.domain,
+				)
+			}
+
+			if err != nil && !errors.Is(err, db.ErrNoEntries) {
+				// Proper error.
+				log.Errorf(ctx, "db error getting mentioned account: %v", err)
+				return false
+			}
+
+			if acc == nil {
+				// We don't know this nerd!
+				return false
+			}
+
+			if acc.ID == receiver.ID {
+				// This is us, doesn't count.
+				return false
+			}
+
+			follows, err := f.state.DB.IsFollowing(ctx, receiver.ID, acc.ID)
+			if err != nil {
+				// Proper error.
+				log.Errorf(ctx, "db error checking follow status: %v", err)
+				return false
+			}
+
+			if follows {
+				// We follow this nerd.
+				return true
+			}
+
+			// We don't follow this nerd, but
+			// have we requested to follow them?
+			followRequested, err := f.state.DB.IsFollowRequested(ctx, receiver.ID, acc.ID)
+			if err != nil {
+				// Proper error.
+				log.Errorf(ctx, "db error checking follow req status: %v", err)
+				return false
+			}
+
+			return followRequested
+		},
+	)
+}
+
+// errantLinks returns true if any http/https
+// link discovered in the statusable content + cw
+// is not either a mention link, or a hashtag link.
+func (f *Filter) errantLinks(
+	ctx context.Context,
+	statusable ap.Statusable,
+	mentions []preppedMention,
+	hashtags []*gtsmodel.Tag,
+) bool {
+	// Concatenate the cw with the
+	// content to check for links in both.
+	cw := ap.ExtractSummary(statusable)
+	content := ap.ExtractContent(statusable)
+	concat := cw + " " + content.Content
+
+	// Store link string alongside link
+	// URI to avoid stringifying twice.
+	type preppedLink struct {
+		*url.URL
+		str string
+	}
+
+	// Find + parse every http/https link in the status.
+	rawLinks := regexes.LinkScheme.FindAllString(concat, -1)
+	links := make([]preppedLink, 0, len(rawLinks))
+	for _, rawLink := range rawLinks {
+		linkURI, err := url.Parse(rawLink)
+		if err != nil {
+			log.Debugf(ctx,
+				"malformed link in status: %v",
+				err,
+			)
+			// Ignore bad links
+			// for spam checking.
+			continue
+		}
+
+		links = append(links, preppedLink{
+			URL: linkURI,
+			str: rawLink,
+		})
+	}
+
+	// For each link in the status, try to
+	// match it to a hashtag or a mention.
+	// If we can't, we have an errant link.
+	for _, link := range links {
+		hashtagLink := slices.ContainsFunc(
+			hashtags,
+			func(hashtag *gtsmodel.Tag) bool {
+				// If a link is to the href
+				// of a hashtag, it's fine.
+				return strings.EqualFold(
+					link.str,
+					hashtag.Href,
+				)
+			},
+		)
+
+		if hashtagLink {
+			// This link is accounted for.
+			// Move to the next one.
+			continue
+		}
+
+		mentionLink := slices.ContainsFunc(
+			mentions,
+			func(mention preppedMention) bool {
+				// If link is straight up to the URI
+				// of a mentioned account, it's fine.
+				if strings.EqualFold(
+					link.str,
+					mention.TargetAccountURI,
+				) {
+					return true
+				}
+
+				// Link might be to an account URL rather
+				// than URI. This is a bit trickier because
+				// we can't predict the format of such URLs,
+				// and it's difficult to reconstruct them
+				// while also taking account of different
+				// host + account-domain values.
+				//
+				// So, just check if this link is on the same
+				// host as the mentioned account, or at least
+				// shares a host with it.
+				if link.Host == mention.domain {
+					// Same host.
+					return true
+				}
+
+				// Shares a host if it has at least two
+				// components from the right in common.
+				common := dns.CompareDomainName(
+					link.Host,
+					mention.domain,
+				)
+				return common >= 2
+			},
+		)
+
+		if mentionLink {
+			// This link is accounted for.
+			// Move to the next one.
+			continue
+		}
+
+		// Not a hashtag link
+		// or a mention link,
+		// so it's errant.
+		return true
+	}
+
+	// All links OK, or
+	// no links found.
+	return false
+}
diff --git a/internal/filter/spam/statusable_test.go b/internal/filter/spam/statusable_test.go
new file mode 100644
index 000000000..db88454ee
--- /dev/null
+++ b/internal/filter/spam/statusable_test.go
@@ -0,0 +1,780 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package spam_test
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"testing"
+
+	"github.com/stretchr/testify/suite"
+	"github.com/superseriousbusiness/gotosocial/internal/ap"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/id"
+)
+
+type StatusableTestSuite struct {
+	FilterStandardTestSuite
+}
+
+const (
+	// Message that mentions 5 people (including receiver),
+	// and contains a errant link.
+	spam1 = `{
+  "@context": [
+    "https://www.w3.org/ns/activitystreams",
+    {
+      "ostatus": "http://ostatus.org#",
+      "atomUri": "ostatus:atomUri",
+      "inReplyToAtomUri": "ostatus:inReplyToAtomUri",
+      "conversation": "ostatus:conversation",
+      "sensitive": "as:sensitive",
+      "toot": "http://joinmastodon.org/ns#",
+      "votersCount": "toot:votersCount"
+    }
+  ],
+  "id": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562",
+  "type": "Note",
+  "summary": null,
+  "inReplyTo": null,
+  "published": "2024-02-24T07:06:14Z",
+  "url": "http://fossbros-anonymous.io/@foss_satan/111985188827079562",
+  "attributedTo": "http://fossbros-anonymous.io/users/foss_satan",
+  "to": [
+    "https://www.w3.org/ns/activitystreams#Public"
+  ],
+  "cc": [
+    "http://fossbros-anonymous.io/users/foss_satan/followers",
+    "https://example.org/users/9gol6f8zff",
+    "https://example.net/users/nityosan",
+    "https://a.misskey.instance.com/users/9c06ylkgsx",
+    "https://another.misskey.instance.com/users/9eklgce5yk",
+    "http://localhost:8080/users/the_mighty_zork"
+  ],
+  "sensitive": false,
+  "atomUri": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562",
+  "inReplyToAtomUri": null,
+  "content": "<p><a href=\"https://spammylink.org/\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" translate=\"no\"><span class=\"invisible\">https://</span><span class=\"\">spammylink.org/</span><span class=\"invisible\"></span></a></p><p><span class=\"h-card\" translate=\"no\"><a href=\"https://example.org/@Nao_ya_ia22\" class=\"u-url mention\">@<span>Nao_ya_ia22</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"https://example.net/@nityosan\" class=\"u-url mention\">@<span>nityosan</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"https://a.misskey.instance.com/@FIzxive\" class=\"u-url mention\">@<span>FIzxive</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"https://another.misskey.instance.com/@mendako\" class=\"u-url mention\">@<span>mendako</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"http://localhost:8080/@the_mighty_zork\" class=\"u-url mention\">@<span>the_mighty_zork</span></a></span></p>",
+  "attachment": [],
+  "tag": [
+    {
+      "type": "Mention",
+      "href": "https://example.org/users/9gol6f8zff",
+      "name": "@Nao_ya_ia22@example.org"
+    },
+    {
+      "type": "Mention",
+      "href": "https://example.net/users/nityosan",
+      "name": "@nityosan@example.net"
+    },
+    {
+      "type": "Mention",
+      "href": "https://a.misskey.instance.com/users/9c06ylkgsx",
+      "name": "@FIzxive@a.misskey.instance.com"
+    },
+    {
+      "type": "Mention",
+      "href": "https://another.misskey.instance.com/users/9eklgce5yk",
+      "name": "@mendako@another.misskey.instance.com"
+    },
+    {
+      "type": "Mention",
+      "href": "http://localhost:8080/users/the_mighty_zork",
+      "name": "@the_mighty_zork@localhost:8080"
+    }
+  ],
+  "replies": {
+    "id": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies",
+    "type": "Collection",
+    "first": {
+      "type": "CollectionPage",
+      "next": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies?only_other_accounts=true&page=true",
+      "partOf": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies",
+      "items": []
+    }
+  }
+}`
+
+	// Message that mentions 4 people (including receiver),
+	// and contains a errant link.
+	spam2 = `{
+  "@context": [
+    "https://www.w3.org/ns/activitystreams",
+    {
+      "ostatus": "http://ostatus.org#",
+      "atomUri": "ostatus:atomUri",
+      "inReplyToAtomUri": "ostatus:inReplyToAtomUri",
+      "conversation": "ostatus:conversation",
+      "sensitive": "as:sensitive",
+      "toot": "http://joinmastodon.org/ns#",
+      "votersCount": "toot:votersCount"
+    }
+  ],
+  "id": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562",
+  "type": "Note",
+  "summary": null,
+  "inReplyTo": null,
+  "published": "2024-02-24T07:06:14Z",
+  "url": "http://fossbros-anonymous.io/@foss_satan/111985188827079562",
+  "attributedTo": "http://fossbros-anonymous.io/users/foss_satan",
+  "to": [
+    "https://www.w3.org/ns/activitystreams#Public"
+  ],
+  "cc": [
+    "http://fossbros-anonymous.io/users/foss_satan/followers",
+    "https://example.net/users/nityosan",
+    "https://a.misskey.instance.com/users/9c06ylkgsx",
+    "https://another.misskey.instance.com/users/9eklgce5yk",
+    "http://localhost:8080/users/the_mighty_zork"
+  ],
+  "sensitive": false,
+  "atomUri": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562",
+  "inReplyToAtomUri": null,
+  "content": "<p><a href=\"https://spammylink.org/\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" translate=\"no\"><span class=\"invisible\">https://</span><span class=\"\">spammylink.org/</span><span class=\"invisible\"></span></a></p><p><span class=\"h-card\" translate=\"no\"><a href=\"https://example.net/@nityosan\" class=\"u-url mention\">@<span>nityosan</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"https://a.misskey.instance.com/@FIzxive\" class=\"u-url mention\">@<span>FIzxive</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"https://another.misskey.instance.com/@mendako\" class=\"u-url mention\">@<span>mendako</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"http://localhost:8080/@the_mighty_zork\" class=\"u-url mention\">@<span>the_mighty_zork</span></a></span></p>",
+  "attachment": [],
+  "tag": [
+    {
+      "type": "Mention",
+      "href": "https://example.net/users/nityosan",
+      "name": "@nityosan@example.net"
+    },
+    {
+      "type": "Mention",
+      "href": "https://a.misskey.instance.com/users/9c06ylkgsx",
+      "name": "@FIzxive@a.misskey.instance.com"
+    },
+    {
+      "type": "Mention",
+      "href": "https://another.misskey.instance.com/users/9eklgce5yk",
+      "name": "@mendako@another.misskey.instance.com"
+    },
+    {
+      "type": "Mention",
+      "href": "http://localhost:8080/users/the_mighty_zork",
+      "name": "@the_mighty_zork@localhost:8080"
+    }
+  ],
+  "replies": {
+    "id": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies",
+    "type": "Collection",
+    "first": {
+      "type": "CollectionPage",
+      "next": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies?only_other_accounts=true&page=true",
+      "partOf": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies",
+      "items": []
+    }
+  }
+}`
+
+	// Message that mentions 4 people (including receiver),
+	// but contains no errant links.
+	spam3 = `{
+  "@context": [
+    "https://www.w3.org/ns/activitystreams",
+    {
+      "ostatus": "http://ostatus.org#",
+      "atomUri": "ostatus:atomUri",
+      "inReplyToAtomUri": "ostatus:inReplyToAtomUri",
+      "conversation": "ostatus:conversation",
+      "sensitive": "as:sensitive",
+      "toot": "http://joinmastodon.org/ns#",
+      "votersCount": "toot:votersCount"
+    }
+  ],
+  "id": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562",
+  "type": "Note",
+  "summary": null,
+  "inReplyTo": null,
+  "published": "2024-02-24T07:06:14Z",
+  "url": "http://fossbros-anonymous.io/@foss_satan/111985188827079562",
+  "attributedTo": "http://fossbros-anonymous.io/users/foss_satan",
+  "to": [
+    "https://www.w3.org/ns/activitystreams#Public"
+  ],
+  "cc": [
+    "http://fossbros-anonymous.io/users/foss_satan/followers",
+    "https://example.net/users/nityosan",
+    "https://a.misskey.instance.com/users/9c06ylkgsx",
+    "https://another.misskey.instance.com/users/9eklgce5yk",
+    "http://localhost:8080/users/the_mighty_zork"
+  ],
+  "sensitive": false,
+  "atomUri": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562",
+  "inReplyToAtomUri": null,
+  "content": "<p><span class=\"h-card\" translate=\"no\"><a href=\"https://example.net/@nityosan\" class=\"u-url mention\">@<span>nityosan</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"https://a.misskey.instance.com/@FIzxive\" class=\"u-url mention\">@<span>FIzxive</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"https://another.misskey.instance.com/@mendako\" class=\"u-url mention\">@<span>mendako</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"http://localhost:8080/@the_mighty_zork\" class=\"u-url mention\">@<span>the_mighty_zork</span></a></span></p>",
+  "attachment": [],
+  "tag": [
+    {
+      "type": "Mention",
+      "href": "https://example.net/users/nityosan",
+      "name": "@nityosan@example.net"
+    },
+    {
+      "type": "Mention",
+      "href": "https://a.misskey.instance.com/users/9c06ylkgsx",
+      "name": "@FIzxive@a.misskey.instance.com"
+    },
+    {
+      "type": "Mention",
+      "href": "https://another.misskey.instance.com/users/9eklgce5yk",
+      "name": "@mendako@another.misskey.instance.com"
+    },
+    {
+      "type": "Mention",
+      "href": "http://localhost:8080/users/the_mighty_zork",
+      "name": "@the_mighty_zork@localhost:8080"
+    }
+  ],
+  "replies": {
+    "id": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies",
+    "type": "Collection",
+    "first": {
+      "type": "CollectionPage",
+      "next": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies?only_other_accounts=true&page=true",
+      "partOf": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies",
+      "items": []
+    }
+  }
+}`
+
+	// Message that mentions 4 people (including receiver),
+	// contains no errant links, but 1 attachment.
+	spam4 = `{
+  "@context": [
+    "https://www.w3.org/ns/activitystreams",
+    {
+      "ostatus": "http://ostatus.org#",
+      "atomUri": "ostatus:atomUri",
+      "inReplyToAtomUri": "ostatus:inReplyToAtomUri",
+      "conversation": "ostatus:conversation",
+      "sensitive": "as:sensitive",
+      "toot": "http://joinmastodon.org/ns#",
+      "votersCount": "toot:votersCount"
+    }
+  ],
+  "id": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562",
+  "type": "Note",
+  "summary": null,
+  "inReplyTo": null,
+  "published": "2024-02-24T07:06:14Z",
+  "url": "http://fossbros-anonymous.io/@foss_satan/111985188827079562",
+  "attributedTo": "http://fossbros-anonymous.io/users/foss_satan",
+  "to": [
+    "https://www.w3.org/ns/activitystreams#Public"
+  ],
+  "cc": [
+    "http://fossbros-anonymous.io/users/foss_satan/followers",
+    "https://example.net/users/nityosan",
+    "https://a.misskey.instance.com/users/9c06ylkgsx",
+    "https://another.misskey.instance.com/users/9eklgce5yk",
+    "http://localhost:8080/users/the_mighty_zork"
+  ],
+  "sensitive": false,
+  "atomUri": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562",
+  "inReplyToAtomUri": null,
+  "content": "<p><span class=\"h-card\" translate=\"no\"><a href=\"https://example.net/@nityosan\" class=\"u-url mention\">@<span>nityosan</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"https://a.misskey.instance.com/@FIzxive\" class=\"u-url mention\">@<span>FIzxive</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"https://another.misskey.instance.com/@mendako\" class=\"u-url mention\">@<span>mendako</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"http://localhost:8080/@the_mighty_zork\" class=\"u-url mention\">@<span>the_mighty_zork</span></a></span></p>",
+  "attachment": [
+    {
+      "blurhash": "LNJRdVM{00Rj%Mayt7j[4nWBofRj",
+      "mediaType": "image/jpeg",
+      "name": "",
+      "type": "Document",
+      "url": "http://fossbros-anonymous.io/fileserver/01F8MH17FWEB39HZJ76B6VXSKF/attachment/original/01F8MH6NEM8D7527KZAECTCR76.jpg"
+    }
+  ],
+  "tag": [
+    {
+      "type": "Mention",
+      "href": "https://example.net/users/nityosan",
+      "name": "@nityosan@example.net"
+    },
+    {
+      "type": "Mention",
+      "href": "https://a.misskey.instance.com/users/9c06ylkgsx",
+      "name": "@FIzxive@a.misskey.instance.com"
+    },
+    {
+      "type": "Mention",
+      "href": "https://another.misskey.instance.com/users/9eklgce5yk",
+      "name": "@mendako@another.misskey.instance.com"
+    },
+    {
+      "type": "Mention",
+      "href": "http://localhost:8080/users/the_mighty_zork",
+      "name": "@the_mighty_zork@localhost:8080"
+    }
+  ],
+  "replies": {
+    "id": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies",
+    "type": "Collection",
+    "first": {
+      "type": "CollectionPage",
+      "next": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies?only_other_accounts=true&page=true",
+      "partOf": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies",
+      "items": []
+    }
+  }
+}`
+
+	// Message that mentions 4 people (including receiver),
+	// and contains a errant link, and receiver follows
+	// another mentioned account.
+	spam5 = `{
+  "@context": [
+    "https://www.w3.org/ns/activitystreams",
+    {
+      "ostatus": "http://ostatus.org#",
+      "atomUri": "ostatus:atomUri",
+      "inReplyToAtomUri": "ostatus:inReplyToAtomUri",
+      "conversation": "ostatus:conversation",
+      "sensitive": "as:sensitive",
+      "toot": "http://joinmastodon.org/ns#",
+      "votersCount": "toot:votersCount"
+    }
+  ],
+  "id": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562",
+  "type": "Note",
+  "summary": null,
+  "inReplyTo": null,
+  "published": "2024-02-24T07:06:14Z",
+  "url": "http://fossbros-anonymous.io/@foss_satan/111985188827079562",
+  "attributedTo": "http://fossbros-anonymous.io/users/foss_satan",
+  "to": [
+    "https://www.w3.org/ns/activitystreams#Public"
+  ],
+  "cc": [
+    "http://fossbros-anonymous.io/users/foss_satan/followers",
+    "https://example.net/users/nityosan",
+    "https://a.misskey.instance.com/users/9c06ylkgsx",
+    "http://localhost:8080/users/admin",
+    "http://localhost:8080/users/the_mighty_zork"
+  ],
+  "sensitive": false,
+  "atomUri": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562",
+  "inReplyToAtomUri": null,
+  "content": "<p><a href=\"https://spammylink.org/\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" translate=\"no\"><span class=\"invisible\">https://</span><span class=\"\">spammylink.org/</span><span class=\"invisible\"></span></a></p><p><span class=\"h-card\" translate=\"no\"><a href=\"https://example.net/@nityosan\" class=\"u-url mention\">@<span>nityosan</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"https://a.misskey.instance.com/@FIzxive\" class=\"u-url mention\">@<span>FIzxive</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"http://localhost:8080/@admin\" class=\"u-url mention\">@<span>admin</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"http://localhost:8080/@the_mighty_zork\" class=\"u-url mention\">@<span>the_mighty_zork</span></a></span></p>",
+  "attachment": [],
+  "tag": [
+    {
+      "type": "Mention",
+      "href": "https://example.net/users/nityosan",
+      "name": "@nityosan@example.net"
+    },
+    {
+      "type": "Mention",
+      "href": "https://a.misskey.instance.com/users/9c06ylkgsx",
+      "name": "@FIzxive@a.misskey.instance.com"
+    },
+    {
+      "type": "Mention",
+      "href": "http://localhost:8080/users/admin",
+      "name": "@admin@localhost:8080"
+    },
+    {
+      "type": "Mention",
+      "href": "http://localhost:8080/users/the_mighty_zork",
+      "name": "@the_mighty_zork@localhost:8080"
+    }
+  ],
+  "replies": {
+    "id": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies",
+    "type": "Collection",
+    "first": {
+      "type": "CollectionPage",
+      "next": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies?only_other_accounts=true&page=true",
+      "partOf": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies",
+      "items": []
+    }
+  }
+}`
+
+	// Message that mentions 3 people, contains a
+	// errant link, and receiver follows another
+	// mentioned account. However, receiver is not mentioned.
+	spam6 = `{
+  "@context": [
+    "https://www.w3.org/ns/activitystreams",
+    {
+      "ostatus": "http://ostatus.org#",
+      "atomUri": "ostatus:atomUri",
+      "inReplyToAtomUri": "ostatus:inReplyToAtomUri",
+      "conversation": "ostatus:conversation",
+      "sensitive": "as:sensitive",
+      "toot": "http://joinmastodon.org/ns#",
+      "votersCount": "toot:votersCount"
+    }
+  ],
+  "id": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562",
+  "type": "Note",
+  "summary": null,
+  "inReplyTo": null,
+  "published": "2024-02-24T07:06:14Z",
+  "url": "http://fossbros-anonymous.io/@foss_satan/111985188827079562",
+  "attributedTo": "http://fossbros-anonymous.io/users/foss_satan",
+  "to": [
+    "https://www.w3.org/ns/activitystreams#Public"
+  ],
+  "cc": [
+    "http://fossbros-anonymous.io/users/foss_satan/followers",
+    "https://example.net/users/nityosan",
+    "https://a.misskey.instance.com/users/9c06ylkgsx",
+    "http://localhost:8080/users/admin"
+  ],
+  "sensitive": false,
+  "atomUri": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562",
+  "inReplyToAtomUri": null,
+  "content": "<p><a href=\"https://spammylink.org/\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" translate=\"no\"><span class=\"invisible\">https://</span><span class=\"\">spammylink.org/</span><span class=\"invisible\"></span></a></p><p><span class=\"h-card\" translate=\"no\"><a href=\"https://example.net/@nityosan\" class=\"u-url mention\">@<span>nityosan</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"https://a.misskey.instance.com/@FIzxive\" class=\"u-url mention\">@<span>FIzxive</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"http://localhost:8080/@admin\" class=\"u-url mention\">@<span>admin</span></a></span></p>",
+  "attachment": [],
+  "tag": [
+    {
+      "type": "Mention",
+      "href": "https://example.net/users/nityosan",
+      "name": "@nityosan@example.net"
+    },
+    {
+      "type": "Mention",
+      "href": "https://a.misskey.instance.com/users/9c06ylkgsx",
+      "name": "@FIzxive@a.misskey.instance.com"
+    },
+    {
+      "type": "Mention",
+      "href": "http://localhost:8080/users/admin",
+      "name": "@admin@localhost:8080"
+    }
+  ],
+  "replies": {
+    "id": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies",
+    "type": "Collection",
+    "first": {
+      "type": "CollectionPage",
+      "next": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies?only_other_accounts=true&page=true",
+      "partOf": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies",
+      "items": []
+    }
+  }
+}`
+
+	// Message that mentions 4 people (including receiver),
+	// and hash a hashtag, but contains no errant links.
+	spam7 = `{
+    "@context": [
+      "https://www.w3.org/ns/activitystreams",
+      {
+        "ostatus": "http://ostatus.org#",
+        "atomUri": "ostatus:atomUri",
+        "inReplyToAtomUri": "ostatus:inReplyToAtomUri",
+        "conversation": "ostatus:conversation",
+        "sensitive": "as:sensitive",
+        "toot": "http://joinmastodon.org/ns#",
+        "votersCount": "toot:votersCount"
+      }
+    ],
+    "id": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562",
+    "type": "Note",
+    "summary": null,
+    "inReplyTo": null,
+    "published": "2024-02-24T07:06:14Z",
+    "url": "http://fossbros-anonymous.io/@foss_satan/111985188827079562",
+    "attributedTo": "http://fossbros-anonymous.io/users/foss_satan",
+    "to": [
+      "https://www.w3.org/ns/activitystreams#Public"
+    ],
+    "cc": [
+      "http://fossbros-anonymous.io/users/foss_satan/followers",
+      "https://example.net/users/nityosan",
+      "https://a.misskey.instance.com/users/9c06ylkgsx",
+      "https://another.misskey.instance.com/users/9eklgce5yk",
+      "http://localhost:8080/users/the_mighty_zork"
+    ],
+    "sensitive": false,
+    "atomUri": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562",
+    "inReplyToAtomUri": null,
+    "content": "<p><a href=\"https://fossbros-anonymous.io/tags/gotosocial\" class=\"mention hashtag\" rel=\"tag\">#<span>gotosocial</span></a> smells<br/><br/><span class=\"h-card\" translate=\"no\"><a href=\"https://example.net/@nityosan\" class=\"u-url mention\">@<span>nityosan</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"https://a.misskey.instance.com/@FIzxive\" class=\"u-url mention\">@<span>FIzxive</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"https://another.misskey.instance.com/@mendako\" class=\"u-url mention\">@<span>mendako</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"http://localhost:8080/@the_mighty_zork\" class=\"u-url mention\">@<span>the_mighty_zork</span></a></span></p>",
+    "attachment": [],
+    "tag": [
+      {
+        "type": "Mention",
+        "href": "https://example.net/users/nityosan",
+        "name": "@nityosan@example.net"
+      },
+      {
+        "type": "Mention",
+        "href": "https://a.misskey.instance.com/users/9c06ylkgsx",
+        "name": "@FIzxive@a.misskey.instance.com"
+      },
+      {
+        "type": "Mention",
+        "href": "https://another.misskey.instance.com/users/9eklgce5yk",
+        "name": "@mendako@another.misskey.instance.com"
+      },
+      {
+        "type": "Mention",
+        "href": "http://localhost:8080/users/the_mighty_zork",
+        "name": "@the_mighty_zork@localhost:8080"
+      },
+      {
+        "type": "Hashtag",
+        "href": "https://fossbros-anonymous.io/tags/gotosocial",
+        "name": "#gotosocial"
+      }  
+    ],
+    "replies": {
+      "id": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies",
+      "type": "Collection",
+      "first": {
+        "type": "CollectionPage",
+        "next": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies?only_other_accounts=true&page=true",
+        "partOf": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies",
+        "items": []
+      }
+    }
+  }`
+
+	// Same as spam7, except message doesn't
+	// have a hashtag in the tags array.
+	spam8 = `{
+    "@context": [
+      "https://www.w3.org/ns/activitystreams",
+      {
+        "ostatus": "http://ostatus.org#",
+        "atomUri": "ostatus:atomUri",
+        "inReplyToAtomUri": "ostatus:inReplyToAtomUri",
+        "conversation": "ostatus:conversation",
+        "sensitive": "as:sensitive",
+        "toot": "http://joinmastodon.org/ns#",
+        "votersCount": "toot:votersCount"
+      }
+    ],
+    "id": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562",
+    "type": "Note",
+    "summary": null,
+    "inReplyTo": null,
+    "published": "2024-02-24T07:06:14Z",
+    "url": "http://fossbros-anonymous.io/@foss_satan/111985188827079562",
+    "attributedTo": "http://fossbros-anonymous.io/users/foss_satan",
+    "to": [
+      "https://www.w3.org/ns/activitystreams#Public"
+    ],
+    "cc": [
+      "http://fossbros-anonymous.io/users/foss_satan/followers",
+      "https://example.net/users/nityosan",
+      "https://a.misskey.instance.com/users/9c06ylkgsx",
+      "https://another.misskey.instance.com/users/9eklgce5yk",
+      "http://localhost:8080/users/the_mighty_zork"
+    ],
+    "sensitive": false,
+    "atomUri": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562",
+    "inReplyToAtomUri": null,
+    "content": "<p><a href=\"https://fossbros-anonymous.io/tags/gotosocial\" class=\"mention hashtag\" rel=\"tag\">#<span>gotosocial</span></a> smells<br/><br/><span class=\"h-card\" translate=\"no\"><a href=\"https://example.net/@nityosan\" class=\"u-url mention\">@<span>nityosan</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"https://a.misskey.instance.com/@FIzxive\" class=\"u-url mention\">@<span>FIzxive</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"https://another.misskey.instance.com/@mendako\" class=\"u-url mention\">@<span>mendako</span></a></span><br /><span class=\"h-card\" translate=\"no\"><a href=\"http://localhost:8080/@the_mighty_zork\" class=\"u-url mention\">@<span>the_mighty_zork</span></a></span></p>",
+    "attachment": [],
+    "tag": [
+      {
+        "type": "Mention",
+        "href": "https://example.net/users/nityosan",
+        "name": "@nityosan@example.net"
+      },
+      {
+        "type": "Mention",
+        "href": "https://a.misskey.instance.com/users/9c06ylkgsx",
+        "name": "@FIzxive@a.misskey.instance.com"
+      },
+      {
+        "type": "Mention",
+        "href": "https://another.misskey.instance.com/users/9eklgce5yk",
+        "name": "@mendako@another.misskey.instance.com"
+      },
+      {
+        "type": "Mention",
+        "href": "http://localhost:8080/users/the_mighty_zork",
+        "name": "@the_mighty_zork@localhost:8080"
+      }
+    ],
+    "replies": {
+      "id": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies",
+      "type": "Collection",
+      "first": {
+        "type": "CollectionPage",
+        "next": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies?only_other_accounts=true&page=true",
+        "partOf": "http://fossbros-anonymous.io/users/foss_satan/statuses/111985188827079562/replies",
+        "items": []
+      }
+    }
+  }`
+)
+
+func (suite *StatusableTestSuite) TestStatusableOK() {
+	var (
+		ctx       = context.Background()
+		receiver  = suite.testAccounts["local_account_1"]
+		requester = suite.testAccounts["remote_account_1"]
+	)
+
+	type testStruct struct {
+		message string
+		check   func(error)
+	}
+
+	for _, test := range []testStruct{
+		{
+			// SPAM: status mentions 5 or more people
+			message: spam1,
+			check: func(err error) {
+				suite.True(gtserror.IsSpam(err), "expected Spam, got %+v", err)
+			},
+		},
+		{
+			// SPAM: receiver doesn't know a mentioned account, and status has attachments or errant links
+			message: spam2,
+			check: func(err error) {
+				suite.True(gtserror.IsSpam(err), "expected Spam, got %+v", err)
+			},
+		},
+		{
+			// NOT SPAM: receiver doesn't know a mentioned account, but status has no attachments or errant links
+			message: spam3,
+			check: func(err error) {
+				suite.NoError(err, "expected not spam, got %+v", err)
+			},
+		},
+		{
+			// SPAM: receiver doesn't know a mentioned account, and status has attachments or errant links
+			message: spam4,
+			check: func(err error) {
+				suite.True(gtserror.IsSpam(err), "expected Spam, got %+v", err)
+			},
+		},
+		{
+			// NOT SPAM: receiver knows a mentioned account
+			message: spam5,
+			check: func(err error) {
+				suite.NoError(err, "expected not spam, got %+v", err)
+			},
+		},
+		{
+			// SPAM: receiver does not follow requester, and is not mentioned
+			message: spam6,
+			check: func(err error) {
+				suite.True(gtserror.IsNotRelevant(err), "expected NotRelevant, got %+v", err)
+			},
+		},
+		{
+			// NOT SPAM: receiver doesn't know a mentioned account, but status has no attachments or errant links
+			message: spam7,
+			check: func(err error) {
+				suite.NoError(err, "expected not spam, got %+v", err)
+			},
+		},
+		{
+			// SPAM: receiver doesn't know a mentioned account, and status has attachments or errant links
+			message: spam8,
+			check: func(err error) {
+				suite.True(gtserror.IsSpam(err), "expected Spam, got %+v", err)
+			},
+		},
+	} {
+		rc := io.NopCloser(bytes.NewReader([]byte(test.message)))
+
+		statusable, err := ap.ResolveStatusable(ctx, rc)
+		if err != nil {
+			suite.FailNow(err.Error())
+		}
+
+		err = suite.filter.StatusableOK(ctx, receiver, requester, statusable)
+		test.check(err)
+	}
+
+	// Put a follow in place from receiver to requester.
+	fID := id.NewULID()
+	if err := suite.state.DB.PutFollow(ctx, &gtsmodel.Follow{
+		ID:              fID,
+		URI:             "http://localhost:8080/users/the_mighty_zork/follows/" + fID,
+		AccountID:       receiver.ID,
+		TargetAccountID: requester.ID,
+	}); err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	// Run all the tests again. They should all
+	// be OK since receiver now follows requester.
+	for _, test := range []testStruct{
+		{
+			message: spam1,
+			check: func(err error) {
+				suite.NoError(err, "expected not spam, got %+v", err)
+			},
+		},
+		{
+			message: spam2,
+			check: func(err error) {
+				suite.NoError(err, "expected not spam, got %+v", err)
+			},
+		},
+		{
+			message: spam3,
+			check: func(err error) {
+				suite.NoError(err, "expected not spam, got %+v", err)
+			},
+		},
+		{
+			message: spam4,
+			check: func(err error) {
+				suite.NoError(err, "expected not spam, got %+v", err)
+			},
+		},
+		{
+			message: spam5,
+			check: func(err error) {
+				suite.NoError(err, "expected not spam, got %+v", err)
+			},
+		},
+		{
+			message: spam6,
+			check: func(err error) {
+				suite.NoError(err, "expected not spam, got %+v", err)
+			},
+		},
+		{
+			message: spam7,
+			check: func(err error) {
+				suite.NoError(err, "expected not spam, got %+v", err)
+			},
+		},
+		{
+			message: spam8,
+			check: func(err error) {
+				suite.NoError(err, "expected not spam, got %+v", err)
+			},
+		},
+	} {
+		rc := io.NopCloser(bytes.NewReader([]byte(test.message)))
+
+		statusable, err := ap.ResolveStatusable(ctx, rc)
+		if err != nil {
+			suite.FailNow(err.Error())
+		}
+
+		err = suite.filter.StatusableOK(ctx, receiver, requester, statusable)
+		test.check(err)
+	}
+}
+
+func TestStatusableTestSuite(t *testing.T) {
+	suite.Run(t, &StatusableTestSuite{})
+}