server/tests: add func.tags tests

8 files changed, 480 insertions, 469 deletions

diff --git a/server/szurubooru/func/tags.py b/server/szurubooru/func/tags.py
index 83579fd..433a7d9 100644
--- a/server/szurubooru/func/tags.py
+++ b/server/szurubooru/func/tags.py
@@ -238,12 +238,14 @@ def update_tag_names(tag, names):
         if not _check_name_intersection_case_sensitive(_get_plain_names(tag), [name]):
             tag.names.append(db.TagName(name))
 
+# TODO: what to do with relations that do not yet exist?
 def update_tag_implications(tag, relations):
     assert tag
     if _check_name_intersection(_get_plain_names(tag), relations):
         raise InvalidTagRelationError('Tag cannot imply itself.')
     tag.implications = get_tags_by_names(relations)
 
+# TODO: what to do with relations that do not yet exist?
 def update_tag_suggestions(tag, relations):
     assert tag
     if _check_name_intersection(_get_plain_names(tag), relations):
diff --git a/server/szurubooru/tests/api/test_tag_creating.py b/server/szurubooru/tests/api/test_tag_creating.py
index 6c48ab2..3112054 100644
--- a/server/szurubooru/tests/api/test_tag_creating.py
+++ b/server/szurubooru/tests/api/test_tag_creating.py
@@ -120,49 +120,6 @@ def test_omitting_optional_field(test_ctx, field):
             user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)))
     assert result is not None
 
-def test_duplicating_names(test_ctx):
-    result = test_ctx.api.post(
-        test_ctx.context_factory(
-            input={
-                'names': ['tag1', 'TAG1'],
-                'category': 'meta',
-                'suggestions': [],
-                'implications': [],
-            },
-            user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)))
-    assert result['names'] == ['tag1']
-    assert result['category'] == 'meta'
-    tag = tags.get_tag_by_name('tag1')
-    assert [tag_name.name for tag_name in tag.names] == ['tag1']
-
-def test_trying_to_use_existing_name(test_ctx):
-    db.session.add_all([
-        test_ctx.tag_factory(names=['used1']),
-        test_ctx.tag_factory(names=['used2']),
-    ])
-    db.session.commit()
-    with pytest.raises(tags.TagAlreadyExistsError):
-        test_ctx.api.post(
-            test_ctx.context_factory(
-                input={
-                    'names': ['used1', 'unused'],
-                    'category': 'meta',
-                    'suggestions': [],
-                    'implications': [],
-                },
-                user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)))
-    with pytest.raises(tags.TagAlreadyExistsError):
-        test_ctx.api.post(
-            test_ctx.context_factory(
-                input={
-                    'names': ['USED2', 'unused'],
-                    'category': 'meta',
-                    'suggestions': [],
-                    'implications': [],
-                },
-                user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)))
-    assert tags.try_get_tag_by_name('unused') is None
-
 def test_creating_new_category(test_ctx):
     with pytest.raises(tag_categories.TagCategoryNotFoundError):
         test_ctx.api.post(
@@ -217,51 +174,6 @@ def test_creating_new_suggestions_and_implications(
     for name in ['main'] + expected_suggestions + expected_implications:
         assert tags.try_get_tag_by_name(name) is not None
 
-def test_reusing_suggestions_and_implications(test_ctx):
-    db.session.add_all([
-        test_ctx.tag_factory(names=['tag1', 'tag2']),
-        test_ctx.tag_factory(names=['tag3']),
-    ])
-    db.session.commit()
-    result = test_ctx.api.post(
-        test_ctx.context_factory(
-            input={
-                'names': ['new'],
-                'category': 'meta',
-                'suggestions': ['TAG2'],
-                'implications': ['tag1'],
-            },
-            user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)))
-    # NOTE: it should export only the first name
-    assert result['suggestions'] == ['tag1']
-    assert result['implications'] == ['tag1']
-    tag = tags.get_tag_by_name('new')
-    assert_relations(tag.suggestions, ['tag1'])
-    assert_relations(tag.implications, ['tag1'])
-
-@pytest.mark.parametrize('input', [
-    {
-        'names': ['tag'],
-        'category': 'meta',
-        'suggestions': ['tag'],
-        'implications': [],
-    },
-    {
-        'names': ['tag'],
-        'category': 'meta',
-        'suggestions': [],
-        'implications': ['tag'],
-    }
-])
-def test_tag_trying_to_relate_to_itself(test_ctx, input):
-    with pytest.raises(tags.TagAlreadyExistsError):
-        test_ctx.api.post(
-            test_ctx.context_factory(
-                input=input,
-                user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)))
-    db.session.rollback()
-    assert tags.try_get_tag_by_name('tag') is None
-
 def test_trying_to_create_tag_without_privileges(test_ctx):
     with pytest.raises(errors.AuthError):
         test_ctx.api.post(
diff --git a/server/szurubooru/tests/api/test_tag_deleting.py b/server/szurubooru/tests/api/test_tag_deleting.py
index eab7c17..350fc0a 100644
--- a/server/szurubooru/tests/api/test_tag_deleting.py
+++ b/server/szurubooru/tests/api/test_tag_deleting.py
@@ -32,21 +32,6 @@ def test_deleting(test_ctx):
     assert db.session.query(db.Tag).count() == 0
     assert os.path.exists(os.path.join(config.config['data_dir'], 'tags.json'))
 
-def test_deleting_used(test_ctx, post_factory):
-    tag = test_ctx.tag_factory(names=['tag'])
-    post = post_factory()
-    post.tags.append(tag)
-    db.session.add_all([tag, post])
-    db.session.commit()
-    test_ctx.api.delete(
-        test_ctx.context_factory(
-            input={'version': 1},
-            user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)),
-        'tag')
-    db.session.refresh(post)
-    assert db.session.query(db.Tag).count() == 0
-    assert post.tags == []
-
 def test_trying_to_delete_non_existing(test_ctx):
     with pytest.raises(tags.TagNotFoundError):
         test_ctx.api.delete(
diff --git a/server/szurubooru/tests/api/test_tag_export.py b/server/szurubooru/tests/api/test_tag_export.py
deleted file mode 100644
index 29fb7e1..0000000
--- a/server/szurubooru/tests/api/test_tag_export.py
+++ /dev/null
@@ -1,64 +0,0 @@
-import datetime
-import os
-import json
-from szurubooru import config, db
-from szurubooru.func import tags
-
-def test_export(
-        tmpdir,
-        query_counter,
-        config_injector,
-        post_factory,
-        tag_factory,
-        tag_category_factory):
-    config_injector({
-        'data_dir': str(tmpdir)
-    })
-    cat1 = tag_category_factory(name='cat1', color='black')
-    cat2 = tag_category_factory(name='cat2', color='white')
-    db.session.add_all([cat1, cat2])
-    db.session.flush()
-    sug1 = tag_factory(names=['sug1'], category=cat1)
-    sug2 = tag_factory(names=['sug2'], category=cat1)
-    imp1 = tag_factory(names=['imp1'], category=cat1)
-    imp2 = tag_factory(names=['imp2'], category=cat1)
-    tag = tag_factory(names=['alias1', 'alias2'], category=cat2)
-    db.session.add_all([tag, sug1, sug2, imp1, imp2, cat1, cat2])
-    post = post_factory()
-    post.tags = [tag]
-    db.session.flush()
-    db.session.add_all([
-        post,
-        db.TagSuggestion(tag.tag_id, sug1.tag_id),
-        db.TagSuggestion(tag.tag_id, sug2.tag_id),
-        db.TagImplication(tag.tag_id, imp1.tag_id),
-        db.TagImplication(tag.tag_id, imp2.tag_id),
-    ])
-    db.session.flush()
-
-    with query_counter:
-        tags.export_to_json()
-        assert len(query_counter.statements) == 5
-
-    export_path = os.path.join(config.config['data_dir'], 'tags.json')
-    assert os.path.exists(export_path)
-    with open(export_path, 'r') as handle:
-        assert json.loads(handle.read()) == {
-            'tags': [
-                {
-                    'names': ['alias1', 'alias2'],
-                    'usages': 1,
-                    'category': 'cat2',
-                    'suggestions': ['sug1', 'sug2'],
-                    'implications': ['imp1', 'imp2'],
-                },
-                {'names': ['sug1'], 'usages': 0, 'category': 'cat1'},
-                {'names': ['sug2'], 'usages': 0, 'category': 'cat1'},
-                {'names': ['imp1'], 'usages': 0, 'category': 'cat1'},
-                {'names': ['imp2'], 'usages': 0, 'category': 'cat1'},
-            ],
-            'categories': [
-                {'name': 'cat1', 'color': 'black'},
-                {'name': 'cat2', 'color': 'white'},
-            ]
-        }
diff --git a/server/szurubooru/tests/api/test_tag_merging.py b/server/szurubooru/tests/api/test_tag_merging.py
index 3f82021..0a64240 100644
--- a/server/szurubooru/tests/api/test_tag_merging.py
+++ b/server/szurubooru/tests/api/test_tag_merging.py
@@ -26,40 +26,6 @@ def test_ctx(
     ret.api = api.TagMergeApi()
     return ret
 
-def test_merging_without_usages(test_ctx, fake_datetime):
-    category = test_ctx.tag_category_factory(name='meta')
-    source_tag = test_ctx.tag_factory(names=['source'])
-    target_tag = test_ctx.tag_factory(names=['target'], category=category)
-    db.session.add_all([source_tag, target_tag])
-    db.session.commit()
-    with fake_datetime('1997-12-01'):
-        result = test_ctx.api.post(
-            test_ctx.context_factory(
-                input={
-                    'removeVersion': 1,
-                    'mergeToVersion': 1,
-                    'remove': 'source',
-                    'mergeTo': 'target',
-                },
-                user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)))
-    assert 'snapshots' in result
-    del result['snapshots']
-    assert result == {
-        'names': ['target'],
-        'category': 'meta',
-        'description': None,
-        'suggestions': [],
-        'implications': [],
-        'creationTime': datetime.datetime(1996, 1, 1),
-        'lastEditTime': None,
-        'usages': 0,
-        'version': 2,
-    }
-    assert tags.try_get_tag_by_name('source') is None
-    tag = tags.get_tag_by_name('target')
-    assert tag is not None
-    assert os.path.exists(os.path.join(config.config['data_dir'], 'tags.json'))
-
 def test_merging_with_usages(test_ctx, fake_datetime, post_factory):
     source_tag = test_ctx.tag_factory(names=['source'])
     target_tag = test_ctx.tag_factory(names=['target'])
@@ -86,83 +52,6 @@ def test_merging_with_usages(test_ctx, fake_datetime, post_factory):
     assert tags.try_get_tag_by_name('source') is None
     assert tags.get_tag_by_name('target').post_count == 1
 
-def test_merging_when_related(test_ctx, fake_datetime):
-    source_tag = test_ctx.tag_factory(names=['source'])
-    target_tag = test_ctx.tag_factory(names=['target'])
-    db.session.add_all([source_tag, target_tag])
-    db.session.flush()
-    referring_tag = test_ctx.tag_factory(names=['parent'])
-    referring_tag.suggestions = [source_tag]
-    referring_tag.implications = [source_tag]
-    db.session.add(referring_tag)
-    db.session.commit()
-    assert tags.try_get_tag_by_name('parent').implications != []
-    assert tags.try_get_tag_by_name('parent').suggestions != []
-    with fake_datetime('1997-12-01'):
-        result = test_ctx.api.post(
-            test_ctx.context_factory(
-                input={
-                    'removeVersion': 1,
-                    'mergeToVersion': 1,
-                    'remove': 'source',
-                    'mergeTo': 'target',
-                },
-                user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)))
-    assert tags.try_get_tag_by_name('source') is None
-    assert tags.try_get_tag_by_name('parent').implications == []
-    assert tags.try_get_tag_by_name('parent').suggestions == []
-
-def test_merging_when_target_exists(test_ctx, fake_datetime, post_factory):
-    source_tag = test_ctx.tag_factory(names=['source'])
-    target_tag = test_ctx.tag_factory(names=['target'])
-    db.session.add_all([source_tag, target_tag])
-    db.session.flush()
-    post1 = post_factory()
-    post1.tags = [source_tag, target_tag]
-    db.session.add_all([post1])
-    db.session.commit()
-    assert source_tag.post_count == 1
-    assert target_tag.post_count == 1
-    with fake_datetime('1997-12-01'):
-        result = test_ctx.api.post(
-            test_ctx.context_factory(
-                input={
-                    'removeVersion': 1,
-                    'mergeToVersion': 1,
-                    'remove': 'source',
-                    'mergeTo': 'target',
-                },
-                user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)))
-    assert tags.try_get_tag_by_name('source') is None
-    assert tags.get_tag_by_name('target').post_count == 1
-
-@pytest.mark.parametrize('input,expected_exception', [
-    ({'remove': None}, tags.TagNotFoundError),
-    ({'remove': ''}, tags.TagNotFoundError),
-    ({'remove': []}, tags.TagNotFoundError),
-    ({'mergeTo': None}, tags.TagNotFoundError),
-    ({'mergeTo': ''}, tags.TagNotFoundError),
-    ({'mergeTo': []}, tags.TagNotFoundError),
-])
-def test_trying_to_pass_invalid_input(test_ctx, input, expected_exception):
-    source_tag = test_ctx.tag_factory(names=['source'])
-    target_tag = test_ctx.tag_factory(names=['target'])
-    db.session.add_all([source_tag, target_tag])
-    db.session.commit()
-    real_input = {
-        'removeVersion': 1,
-        'mergeToVersion': 1,
-        'remove': 'source',
-        'mergeTo': 'target',
-    }
-    for key, value in input.items():
-        real_input[key] = value
-    with pytest.raises(expected_exception):
-        test_ctx.api.post(
-            test_ctx.context_factory(
-                input=real_input,
-                user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)))
-
 @pytest.mark.parametrize(
     'field', ['remove', 'mergeTo', 'removeVersion', 'mergeToVersion'])
 def test_trying_to_omit_mandatory_field(test_ctx, field):
@@ -198,19 +87,6 @@ def test_trying_to_merge_non_existing(test_ctx):
                 input={'remove': 'bad', 'mergeTo': 'good'},
                 user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)))
 
-def test_trying_to_merge_to_itself(test_ctx):
-    db.session.add(test_ctx.tag_factory(names=['good']))
-    db.session.commit()
-    with pytest.raises(tags.InvalidTagRelationError):
-        test_ctx.api.post(
-            test_ctx.context_factory(
-                input={
-                    'removeVersion': 1,
-                    'mergeToVersion': 1,
-                    'remove': 'good',
-                    'mergeTo': 'good'},
-                user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)))
-
 @pytest.mark.parametrize('input', [
     {'names': 'whatever'},
     {'category': 'whatever'},
diff --git a/server/szurubooru/tests/api/test_tag_siblings_retrieving.py b/server/szurubooru/tests/api/test_tag_siblings_retrieving.py
index cddb04a..f3d8e2c 100644
--- a/server/szurubooru/tests/api/test_tag_siblings_retrieving.py
+++ b/server/szurubooru/tests/api/test_tag_siblings_retrieving.py
@@ -28,23 +28,6 @@ def test_ctx(
     ret.api = api.TagSiblingsApi()
     return ret
 
-def test_unused(test_ctx):
-    db.session.add(test_ctx.tag_factory(names=['tag']))
-    result = test_ctx.api.get(
-        test_ctx.context_factory(
-            user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)), 'tag')
-    assert_results(result, [])
-
-def test_used_alone(test_ctx):
-    tag = test_ctx.tag_factory(names=['tag'])
-    post = test_ctx.post_factory()
-    post.tags = [tag]
-    db.session.add_all([post, tag])
-    result = test_ctx.api.get(
-        test_ctx.context_factory(
-            user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)), 'tag')
-    assert_results(result, [])
-
 def test_used_with_others(test_ctx):
     tag1 = test_ctx.tag_factory(names=['tag1'])
     tag2 = test_ctx.tag_factory(names=['tag2'])
@@ -60,33 +43,6 @@ def test_used_with_others(test_ctx):
             user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)), 'tag2')
     assert_results(result, [('tag1', 1)])
 
-def test_used_with_multiple_others(test_ctx):
-    tag1 = test_ctx.tag_factory(names=['tag1'])
-    tag2 = test_ctx.tag_factory(names=['tag2'])
-    tag3 = test_ctx.tag_factory(names=['tag3'])
-    post1 = test_ctx.post_factory()
-    post2 = test_ctx.post_factory()
-    post3 = test_ctx.post_factory()
-    post4 = test_ctx.post_factory()
-    post1.tags = [tag1, tag2, tag3]
-    post2.tags = [tag1, tag3]
-    post3.tags = [tag2]
-    post4.tags = [tag2]
-    db.session.add_all([post1, post2, post3, post4, tag1, tag2, tag3])
-    result = test_ctx.api.get(
-        test_ctx.context_factory(
-            user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)), 'tag1')
-    assert_results(result, [('tag3', 2), ('tag2', 1)])
-    result = test_ctx.api.get(
-        test_ctx.context_factory(
-            user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)), 'tag2')
-    assert_results(result, [('tag1', 1), ('tag3', 1)])
-    result = test_ctx.api.get(
-        test_ctx.context_factory(
-            user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)), 'tag3')
-    # even though tag2 is used more widely, tag1 is more relevant to tag3
-    assert_results(result, [('tag1', 2), ('tag2', 1)])
-
 def test_trying_to_retrieve_non_existing(test_ctx):
     with pytest.raises(tags.TagNotFoundError):
         test_ctx.api.get(
diff --git a/server/szurubooru/tests/api/test_tag_updating.py b/server/szurubooru/tests/api/test_tag_updating.py
index 151f62b..8ec965f 100644
--- a/server/szurubooru/tests/api/test_tag_updating.py
+++ b/server/szurubooru/tests/api/test_tag_updating.py
@@ -124,140 +124,6 @@ def test_trying_to_update_non_existing(test_ctx):
                 user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)),
             'tag1')
 
-@pytest.mark.parametrize('dup_name', ['tag1', 'TAG1'])
-def test_reusing_own_name(test_ctx, dup_name):
-    db.session.add(
-        test_ctx.tag_factory(names=['tag1', 'tag2']))
-    db.session.commit()
-    result = test_ctx.api.put(
-        test_ctx.context_factory(
-            input={'names': [dup_name, 'tag3'], 'version': 1},
-            user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)),
-        'tag1')
-    assert result['names'] == [dup_name, 'tag3']
-    assert tags.try_get_tag_by_name('tag2') is None
-    tag1 = tags.get_tag_by_name('tag1')
-    tag2 = tags.get_tag_by_name('tag3')
-    assert tag1.tag_id == tag2.tag_id
-    assert [name.name for name in tag1.names] == [dup_name, 'tag3']
-
-def test_duplicating_names(test_ctx):
-    db.session.add(
-        test_ctx.tag_factory(names=['tag1', 'tag2']))
-    result = test_ctx.api.put(
-        test_ctx.context_factory(
-            input={'names': ['tag3', 'TAG3'], 'version': 1},
-            user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)),
-        'tag1')
-    assert result['names'] == ['tag3']
-    assert tags.try_get_tag_by_name('tag1') is None
-    assert tags.try_get_tag_by_name('tag2') is None
-    tag = tags.get_tag_by_name('tag3')
-    assert tag is not None
-    assert [tag_name.name for tag_name in tag.names] == ['tag3']
-
-@pytest.mark.parametrize('dup_name', ['tag1', 'TAG1', 'tag2', 'TAG2'])
-def test_trying_to_use_existing_name(test_ctx, dup_name):
-    db.session.add_all([
-        test_ctx.tag_factory(names=['tag1', 'tag2']),
-        test_ctx.tag_factory(names=['tag3', 'tag4'])])
-    db.session.commit()
-    with pytest.raises(tags.TagAlreadyExistsError):
-        test_ctx.api.put(
-            test_ctx.context_factory(
-                input={'names': [dup_name], 'version': 1},
-                user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)),
-            'tag3')
-
-@pytest.mark.parametrize('input,expected_suggestions,expected_implications', [
-    # new relations
-    ({
-        'suggestions': ['sug1', 'sug2'],
-        'implications': ['imp1', 'imp2'],
-    }, ['sug1', 'sug2'], ['imp1', 'imp2']),
-    # overlapping relations
-    ({
-        'suggestions': ['sug', 'shared'],
-        'implications': ['shared', 'imp'],
-    }, ['shared', 'sug'], ['imp', 'shared']),
-    # duplicate relations
-    ({
-        'suggestions': ['sug', 'SUG'],
-        'implications': ['imp', 'IMP'],
-    }, ['sug'], ['imp']),
-    # overlapping duplicate relations
-    ({
-        'suggestions': ['shared1', 'shared2'],
-        'implications': ['SHARED1', 'SHARED2'],
-    }, ['shared1', 'shared2'], ['shared1', 'shared2']),
-])
-def test_updating_new_suggestions_and_implications(
-        test_ctx, input, expected_suggestions, expected_implications):
-    db.session.add(
-        test_ctx.tag_factory(names=['main']))
-    db.session.commit()
-    result = test_ctx.api.put(
-        test_ctx.context_factory(
-            input={**input, **{'version': 1}},
-            user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)),
-        'main')
-    assert result['suggestions'] == expected_suggestions
-    assert result['implications'] == expected_implications
-    tag = tags.get_tag_by_name('main')
-    assert_relations(tag.suggestions, expected_suggestions)
-    assert_relations(tag.implications, expected_implications)
-    for name in ['main'] + expected_suggestions + expected_implications:
-        assert tags.try_get_tag_by_name(name) is not None
-
-def test_reusing_suggestions_and_implications(test_ctx):
-    db.session.add_all([
-        test_ctx.tag_factory(names=['tag1', 'tag2']),
-        test_ctx.tag_factory(names=['tag3']),
-        test_ctx.tag_factory(names=['tag4']),
-    ])
-    db.session.commit()
-    result = test_ctx.api.put(
-        test_ctx.context_factory(
-            input={
-                'names': ['new'],
-                'category': 'meta',
-                'suggestions': ['TAG2'],
-                'implications': ['tag1'],
-                'version': 1,
-            },
-            user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)),
-        'tag4')
-    # NOTE: it should export only the first name
-    assert result['suggestions'] == ['tag1']
-    assert result['implications'] == ['tag1']
-    tag = tags.get_tag_by_name('new')
-    assert_relations(tag.suggestions, ['tag1'])
-    assert_relations(tag.implications, ['tag1'])
-
-@pytest.mark.parametrize('input', [
-    {
-        'names': ['tag1'],
-        'category': 'meta',
-        'suggestions': ['tag1'],
-        'implications': [],
-    },
-    {
-        'names': ['tag1'],
-        'category': 'meta',
-        'suggestions': [],
-        'implications': ['tag1'],
-    }
-])
-def test_trying_to_relate_tag_to_itself(test_ctx, input):
-    db.session.add(test_ctx.tag_factory(names=['tag1']))
-    db.session.commit()
-    with pytest.raises(tags.InvalidTagRelationError):
-        test_ctx.api.put(
-            test_ctx.context_factory(
-                input={**input, **{'version': 1}},
-                user=test_ctx.user_factory(rank=db.User.RANK_REGULAR)),
-            'tag1')
-
 @pytest.mark.parametrize('input', [
     {'names': 'whatever'},
     {'category': 'whatever'},
diff --git a/server/szurubooru/tests/func/test_tags.py b/server/szurubooru/tests/func/test_tags.py
new file mode 100644
index 0000000..25dbc43
--- /dev/null
+++ b/server/szurubooru/tests/func/test_tags.py
@@ -0,0 +1,478 @@
+import os
+import json
+import pytest
+import unittest.mock
+from datetime import datetime
+from szurubooru import db
+from szurubooru.func import tags, tag_categories, cache, snapshots
+
+@pytest.fixture(autouse=True)
+def purge_cache(config_injector):
+    cache.purge()
+
+def _assert_tag_siblings(result, expected_tag_names_and_occurrences):
+    actual_tag_names_and_occurences = []
+    for sibling, occurrences in result:
+        actual_tag_names_and_occurences.append((sibling.names[0].name, occurrences))
+    assert actual_tag_names_and_occurences == expected_tag_names_and_occurrences
+
+@pytest.mark.parametrize('input,expected_tag_names', [
+    ([('a', 'a', True), ('b', 'b', False), ('c', 'c', False)], list('abc')),
+    ([('c', 'a', True), ('b', 'b', False), ('a', 'c', False)], list('cba')),
+    ([('a', 'c', True), ('b', 'b', False), ('c', 'a', False)], list('acb')),
+    ([('a', 'c', False), ('b', 'b', False), ('c', 'a', True)], list('cba')),
+])
+def test_sort_tags(input, expected_tag_names, tag_factory, tag_category_factory):
+    db_tags = []
+    for tag in input:
+        tag_name, category_name, category_is_default = tag
+        db_tags.append(
+            tag_factory(
+                names=[tag_name],
+                category=tag_category_factory(
+                    name=category_name, default=category_is_default)))
+    db.session.add_all(db_tags)
+    actual_tag_names = [tag.names[0].name for tag in tags.sort_tags(db_tags)]
+    assert actual_tag_names == expected_tag_names
+
+def test_serialize_tag_when_empty():
+    assert tags.serialize_tag(None, None) is None
+
+def test_serialize_tag(post_factory, tag_factory, tag_category_factory):
+    with unittest.mock.patch('szurubooru.func.snapshots.get_serialized_history'):
+        snapshots.get_serialized_history.return_value = 'snapshot history'
+
+        tag = tag_factory(
+            names=['tag1', 'tag2'],
+            category=tag_category_factory(name='cat'))
+        tag.tag_id = 1
+        tag.description = 'description'
+        tag.suggestions = [tag_factory(names=['sug1']), tag_factory(names=['sug2'])]
+        tag.implications = [tag_factory(names=['impl1']), tag_factory(names=['impl2'])]
+        tag.last_edit_time = datetime(1998, 1, 1)
+
+        post1 = post_factory()
+        post2 = post_factory()
+        post1.tags = [tag]
+        post2.tags = [tag]
+        db.session.add_all([tag, post1, post2])
+        db.session.flush()
+
+        result = tags.serialize_tag(tag)
+        result['suggestions'].sort()
+        result['implications'].sort()
+
+    assert result ==  {
+        'names': ['tag1', 'tag2'],
+        'version': 1,
+        'category': 'cat',
+        'creationTime': datetime(1996, 1, 1, 0, 0),
+        'lastEditTime': datetime(1998, 1, 1, 0, 0),
+        'description': 'description',
+        'suggestions': ['sug1', 'sug2'],
+        'implications': ['impl1', 'impl2'],
+        'usages': 2,
+        'snapshots': 'snapshot history',
+    }
+
+def test_export_to_json(
+        tmpdir,
+        query_counter,
+        config_injector,
+        post_factory,
+        tag_factory,
+        tag_category_factory):
+    config_injector({'data_dir': str(tmpdir)})
+    cat1 = tag_category_factory(name='cat1', color='black')
+    cat2 = tag_category_factory(name='cat2', color='white')
+    db.session.add_all([cat1, cat2])
+    db.session.flush()
+    sug1 = tag_factory(names=['sug1'], category=cat1)
+    sug2 = tag_factory(names=['sug2'], category=cat1)
+    imp1 = tag_factory(names=['imp1'], category=cat1)
+    imp2 = tag_factory(names=['imp2'], category=cat1)
+    tag = tag_factory(names=['alias1', 'alias2'], category=cat2)
+    db.session.add_all([tag, sug1, sug2, imp1, imp2, cat1, cat2])
+    post = post_factory()
+    post.tags = [tag]
+    db.session.flush()
+    db.session.add_all([
+        post,
+        db.TagSuggestion(tag.tag_id, sug1.tag_id),
+        db.TagSuggestion(tag.tag_id, sug2.tag_id),
+        db.TagImplication(tag.tag_id, imp1.tag_id),
+        db.TagImplication(tag.tag_id, imp2.tag_id),
+    ])
+    db.session.flush()
+
+    with query_counter:
+        tags.export_to_json()
+        assert len(query_counter.statements) == 5
+
+    export_path = os.path.join(str(tmpdir), 'tags.json')
+    assert os.path.exists(export_path)
+    with open(export_path, 'r') as handle:
+        assert json.loads(handle.read()) == {
+            'tags': [
+                {
+                    'names': ['alias1', 'alias2'],
+                    'usages': 1,
+                    'category': 'cat2',
+                    'suggestions': ['sug1', 'sug2'],
+                    'implications': ['imp1', 'imp2'],
+                },
+                {'names': ['sug1'], 'usages': 0, 'category': 'cat1'},
+                {'names': ['sug2'], 'usages': 0, 'category': 'cat1'},
+                {'names': ['imp1'], 'usages': 0, 'category': 'cat1'},
+                {'names': ['imp2'], 'usages': 0, 'category': 'cat1'},
+            ],
+            'categories': [
+                {'name': 'cat1', 'color': 'black'},
+                {'name': 'cat2', 'color': 'white'},
+            ]
+        }
+
+@pytest.mark.parametrize('name_to_search,expected_to_find', [
+    ('name', True),
+    ('NAME', True),
+    ('alias', True),
+    ('ALIAS', True),
+    ('-', False),
+])
+def test_try_get_tag_by_name(name_to_search, expected_to_find, tag_factory):
+    tag = tag_factory(names=['name', 'ALIAS'])
+    db.session.add(tag)
+    if expected_to_find:
+        assert tags.try_get_tag_by_name(name_to_search) == tag
+    else:
+        assert tags.try_get_tag_by_name(name_to_search) is None
+
+@pytest.mark.parametrize('name_to_search,expected_to_find', [
+    ('name', True),
+    ('NAME', True),
+    ('alias', True),
+    ('ALIAS', True),
+    ('-', False),
+])
+def test_get_tag_by_name(name_to_search, expected_to_find, tag_factory):
+    tag = tag_factory(names=['name', 'ALIAS'])
+    db.session.add(tag)
+    if expected_to_find:
+        assert tags.get_tag_by_name(name_to_search) == tag
+    else:
+        with pytest.raises(tags.TagNotFoundError):
+            tags.get_tag_by_name(name_to_search)
+
+@pytest.mark.parametrize('names_to_search,expected_ids', [
+    ([], []),
+    (['name1'], [1]),
+    (['NAME1'], [1]),
+    (['alias1'], [1]),
+    (['ALIAS1'], [1]),
+    (['name2'], [2]),
+    (['name1', 'name1'], [1]),
+    (['name1', 'NAME1'], [1]),
+    (['name1', 'alias1'], [1]),
+    (['name1', 'alias2'], [1, 2]),
+    (['NAME1', 'alias2'], [1, 2]),
+    (['name1', 'ALIAS2'], [1, 2]),
+    (['name2', 'alias1'], [1, 2]),
+])
+def test_get_tag_by_names(names_to_search, expected_ids, tag_factory):
+    tag1 = tag_factory(names=['name1', 'ALIAS1'])
+    tag2 = tag_factory(names=['name2', 'ALIAS2'])
+    tag1.tag_id = 1
+    tag2.tag_id = 2
+    db.session.add_all([tag1, tag2])
+    actual_ids = [tag.tag_id for tag in tags.get_tags_by_names(names_to_search)]
+    assert actual_ids == expected_ids
+
+@pytest.mark.parametrize(
+    'names_to_search,expected_ids,expected_created_names', [
+        ([], [], []),
+        (['name1'], [1], []),
+        (['NAME1'], [1], []),
+        (['alias1'], [1], []),
+        (['ALIAS1'], [1], []),
+        (['name2'], [2], []),
+        (['name1', 'name1'], [1], []),
+        (['name1', 'NAME1'], [1], []),
+        (['name1', 'alias1'], [1], []),
+        (['name1', 'alias2'], [1, 2], []),
+        (['NAME1', 'alias2'], [1, 2], []),
+        (['name1', 'ALIAS2'], [1, 2], []),
+        (['name2', 'alias1'], [1, 2], []),
+        (['new'], [], ['new']),
+        (['new', 'name1'], [1], ['new']),
+        (['new', 'NAME1'], [1], ['new']),
+        (['new', 'alias1'], [1], ['new']),
+        (['new', 'ALIAS1'], [1], ['new']),
+        (['new', 'name2'], [2], ['new']),
+        (['new', 'name1', 'name1'], [1], ['new']),
+        (['new', 'name1', 'NAME1'], [1], ['new']),
+        (['new', 'name1', 'alias1'], [1], ['new']),
+        (['new', 'name1', 'alias2'], [1, 2], ['new']),
+        (['new', 'NAME1', 'alias2'], [1, 2], ['new']),
+        (['new', 'name1', 'ALIAS2'], [1, 2], ['new']),
+        (['new', 'name2', 'alias1'], [1, 2], ['new']),
+        (['new', 'new'], [], ['new']),
+        (['new', 'NEW'], [], ['new']),
+        (['new', 'new2'], [], ['new', 'new2']),
+    ])
+def test_get_or_create_tags_by_names(
+        names_to_search,
+        expected_ids,
+        expected_created_names,
+        tag_factory,
+        tag_category_factory,
+        config_injector):
+    config_injector({'tag_name_regex': '.*'})
+    category = tag_category_factory()
+    tag1 = tag_factory(names=['name1', 'ALIAS1'], category=category)
+    tag2 = tag_factory(names=['name2', 'ALIAS2'], category=category)
+    db.session.add_all([tag1, tag2])
+    result = tags.get_or_create_tags_by_names(names_to_search)
+    actual_ids = [tag.tag_id for tag in result[0]]
+    actual_created_names = [tag.names[0].name for tag in result[1]]
+    assert actual_ids == expected_ids
+    assert actual_created_names == expected_created_names
+
+def test_get_tag_siblings_for_unused(tag_factory, post_factory):
+    tag = tag_factory(names=['tag'])
+    db.session.add(tag)
+    db.session.flush()
+    _assert_tag_siblings(tags.get_tag_siblings(tag), [])
+
+def test_get_tag_siblings_for_used_alone(tag_factory, post_factory):
+    tag = tag_factory(names=['tag'])
+    post = post_factory()
+    post.tags = [tag]
+    db.session.add_all([post, tag])
+    db.session.flush()
+    _assert_tag_siblings(tags.get_tag_siblings(tag), [])
+
+def test_get_tag_siblings_for_used_with_others(tag_factory, post_factory):
+    tag1 = tag_factory(names=['t1'])
+    tag2 = tag_factory(names=['t2'])
+    post = post_factory()
+    post.tags = [tag1, tag2]
+    db.session.add_all([post, tag1, tag2])
+    db.session.flush()
+    _assert_tag_siblings(tags.get_tag_siblings(tag1), [('t2', 1)])
+    _assert_tag_siblings(tags.get_tag_siblings(tag2), [('t1', 1)])
+
+def test_get_tag_siblings_used_for_multiple_others(tag_factory, post_factory):
+    tag1 = tag_factory(names=['t1'])
+    tag2 = tag_factory(names=['t2'])
+    tag3 = tag_factory(names=['t3'])
+    post1 = post_factory()
+    post2 = post_factory()
+    post3 = post_factory()
+    post4 = post_factory()
+    post1.tags = [tag1, tag2, tag3]
+    post2.tags = [tag1, tag3]
+    post3.tags = [tag2]
+    post4.tags = [tag2]
+    db.session.add_all([post1, post2, post3, post4, tag1, tag2, tag3])
+    db.session.flush()
+    _assert_tag_siblings(tags.get_tag_siblings(tag1), [('t3', 2), ('t2', 1)])
+    _assert_tag_siblings(tags.get_tag_siblings(tag2), [('t1', 1), ('t3', 1)])
+    # even though tag2 is used more widely, tag1 is more relevant to tag3
+    _assert_tag_siblings(tags.get_tag_siblings(tag3), [('t1', 2), ('t2', 1)])
+
+def test_delete(tag_factory):
+    tag = tag_factory(names=['tag'])
+    tag.suggestions = [tag_factory(names=['sug'])]
+    tag.implications = [tag_factory(names=['imp'])]
+    db.session.add(tag)
+    db.session.flush()
+    assert db.session.query(db.Tag).count() == 3
+    tags.delete(tag)
+    assert db.session.query(db.Tag).count() == 2
+
+def test_merge_tags_without_usages(tag_factory):
+    source_tag = tag_factory(names=['source'])
+    target_tag = tag_factory(names=['target'])
+    db.session.add_all([source_tag, target_tag])
+    db.session.commit()
+    tags.merge_tags(source_tag, target_tag)
+    db.session.commit()
+    assert tags.try_get_tag_by_name('source') is None
+    tag = tags.get_tag_by_name('target')
+    assert tag is not None
+
+def test_merge_tags_with_usages(tag_factory, post_factory):
+    source_tag = tag_factory(names=['source'])
+    target_tag = tag_factory(names=['target'])
+    post = post_factory()
+    post.tags = [source_tag]
+    db.session.add_all([source_tag, target_tag, post])
+    db.session.commit()
+    assert source_tag.post_count == 1
+    assert target_tag.post_count == 0
+    tags.merge_tags(source_tag, target_tag)
+    db.session.commit()
+    assert tags.try_get_tag_by_name('source') is None
+    assert tags.get_tag_by_name('target').post_count == 1
+
+def test_merge_tags_with_itself(tag_factory, post_factory):
+    source_tag = tag_factory(names=['source'])
+    db.session.add(source_tag)
+    db.session.commit()
+    with pytest.raises(tags.InvalidTagRelationError):
+        tags.merge_tags(source_tag, source_tag)
+
+def test_merge_tags_with_its_child_relation(tag_factory, post_factory):
+    source_tag = tag_factory(names=['source'])
+    target_tag = tag_factory(names=['target'])
+    source_tag.suggestions = [target_tag]
+    source_tag.implications = [target_tag]
+    post = post_factory()
+    post.tags = [source_tag, target_tag]
+    db.session.add_all([source_tag, post])
+    db.session.commit()
+    tags.merge_tags(source_tag, target_tag)
+    db.session.commit()
+    assert tags.try_get_tag_by_name('source') is None
+    assert tags.get_tag_by_name('target').post_count == 1
+
+def test_merge_tags_with_its_parent_relation(tag_factory, post_factory):
+    source_tag = tag_factory(names=['source'])
+    target_tag = tag_factory(names=['target'])
+    target_tag.suggestions = [source_tag]
+    target_tag.implications = [source_tag]
+    post = post_factory()
+    post.tags = [source_tag, target_tag]
+    db.session.add_all([source_tag, target_tag, post])
+    db.session.commit()
+    tags.merge_tags(source_tag, target_tag)
+    db.session.commit()
+    assert tags.try_get_tag_by_name('source') is None
+    assert tags.get_tag_by_name('target').post_count == 1
+
+def test_merge_tags_clears_relations(tag_factory):
+    source_tag = tag_factory(names=['source'])
+    target_tag = tag_factory(names=['target'])
+    referring_tag = tag_factory(names=['parent'])
+    referring_tag.suggestions = [source_tag]
+    referring_tag.implications = [source_tag]
+    db.session.add_all([source_tag, target_tag, referring_tag])
+    db.session.commit()
+    assert tags.try_get_tag_by_name('parent').implications != []
+    assert tags.try_get_tag_by_name('parent').suggestions != []
+    tags.merge_tags(source_tag, target_tag)
+    db.session.commit()
+    assert tags.try_get_tag_by_name('source') is None
+    assert tags.try_get_tag_by_name('parent').implications == []
+    assert tags.try_get_tag_by_name('parent').suggestions == []
+
+def test_merge_tags_when_target_exists(tag_factory, post_factory):
+    source_tag = tag_factory(names=['source'])
+    target_tag = tag_factory(names=['target'])
+    post = post_factory()
+    post.tags = [source_tag, target_tag]
+    db.session.add_all([source_tag, target_tag, post])
+    db.session.commit()
+    assert source_tag.post_count == 1
+    assert target_tag.post_count == 1
+    tags.merge_tags(source_tag, target_tag)
+    db.session.commit()
+    assert tags.try_get_tag_by_name('source') is None
+    assert tags.get_tag_by_name('target').post_count == 1
+
+def test_create_tag(fake_datetime):
+    with unittest.mock.patch('szurubooru.func.tags.update_tag_names'), \
+            unittest.mock.patch('szurubooru.func.tags.update_tag_category_name'), \
+            unittest.mock.patch('szurubooru.func.tags.update_tag_suggestions'), \
+            unittest.mock.patch('szurubooru.func.tags.update_tag_implications'), \
+            fake_datetime('1997-01-01'):
+        tag = tags.create_tag(['name'], 'cat', ['sug'], ['imp'])
+        assert tag.creation_time == datetime(1997, 1, 1)
+        assert tag.last_edit_time is None
+        tags.update_tag_names.assert_called_once_with(tag, ['name'])
+        tags.update_tag_category_name.assert_called_once_with(tag, 'cat')
+        tags.update_tag_suggestions.assert_called_once_with(tag, ['sug'])
+        tags.update_tag_implications.assert_called_once_with(tag, ['imp'])
+
+def test_update_tag_category_name(tag_factory):
+    with unittest.mock.patch('szurubooru.func.tag_categories.get_category_by_name'):
+        tag_categories.get_category_by_name.return_value = 'returned category'
+        tag = tag_factory()
+        tags.update_tag_category_name(tag, 'cat')
+        assert tag_categories.get_category_by_name.called_once_with('cat')
+        assert tag.category == 'returned category'
+
+def test_update_tag_names_to_empty(tag_factory):
+    tag = tag_factory()
+    with pytest.raises(tags.InvalidTagNameError):
+        tags.update_tag_names(tag, [])
+
+def test_update_tag_names_with_invalid_name(config_injector, tag_factory):
+    config_injector({'tag_name_regex': '^[a-z]*$'})
+    tag = tag_factory()
+    with pytest.raises(tags.InvalidTagNameError):
+        tags.update_tag_names(tag, ['0'])
+
+def test_update_tag_names_with_too_long_string(config_injector, tag_factory):
+    config_injector({'tag_name_regex': '^[a-z]*$'})
+    tag = tag_factory()
+    with pytest.raises(tags.InvalidTagNameError):
+        tags.update_tag_names(tag, ['a' * 300])
+
+def test_update_tag_names_with_duplicate_names(config_injector, tag_factory):
+    config_injector({'tag_name_regex': '^[a-z]*$'})
+    tag = tag_factory()
+    tags.update_tag_names(tag, ['a', 'A'])
+    assert [tag_name.name for tag_name in tag.names] == ['a']
+
+def test_update_tag_names_trying_to_use_taken_name(config_injector, tag_factory):
+    config_injector({'tag_name_regex': '^[a-zA-Z]*$'})
+    existing_tag = tag_factory(names=['a'])
+    db.session.add(existing_tag)
+    tag = tag_factory()
+    db.session.add(tag)
+    with pytest.raises(tags.TagAlreadyExistsError):
+        tags.update_tag_names(tag, ['a'])
+    with pytest.raises(tags.TagAlreadyExistsError):
+        tags.update_tag_names(tag, ['A'])
+
+def test_update_tag_names_reusing_own_name(config_injector, tag_factory):
+    config_injector({'tag_name_regex': '^[a-zA-Z]*$'})
+    for name in list('aA'):
+        tag = tag_factory(names=['a'])
+        db.session.add(tag)
+        db.session.flush()
+        tags.update_tag_names(tag, [name])
+        assert [tag_name.name for tag_name in tag.names] == [name]
+        db.session.rollback()
+
+@pytest.mark.parametrize('attempt', ['name', 'NAME', 'alias', 'ALIAS'])
+def test_update_tag_suggestions_with_itself(attempt, tag_factory):
+    tag = tag_factory(names=['name', 'ALIAS'])
+    with pytest.raises(tags.InvalidTagRelationError):
+        tags.update_tag_suggestions(tag, [attempt])
+
+def test_update_tag_suggestions(tag_factory):
+    tag = tag_factory(names=['name', 'ALIAS'])
+    with unittest.mock.patch('szurubooru.func.tags.get_tags_by_names'):
+        tags.get_tags_by_names.return_value = ['returned tags']
+        tags.update_tag_suggestions(tag, ['test'])
+        assert tag.suggestions == ['returned tags']
+
+@pytest.mark.parametrize('attempt', ['name', 'NAME', 'alias', 'ALIAS'])
+def test_update_tag_implications_with_itself(attempt, tag_factory):
+    tag = tag_factory(names=['name', 'ALIAS'])
+    with pytest.raises(tags.InvalidTagRelationError):
+        tags.update_tag_implications(tag, [attempt])
+
+def test_update_tag_implications(tag_factory):
+    tag = tag_factory(names=['name', 'ALIAS'])
+    with unittest.mock.patch('szurubooru.func.tags.get_tags_by_names'):
+        tags.get_tags_by_names.return_value = ['returned tags']
+        tags.update_tag_implications(tag, ['test'])
+        assert tag.implications == ['returned tags']
+
+def test_update_tag_description(tag_factory):
+    tag = tag_factory()
+    tags.update_tag_description(tag, 'test')
+    assert tag.description == 'test'