feat: support --fake for aerich upgrade (#398)

* feat: support `--fake` for aerich upgrade

* Add `--fake` to downgrade

* tests: check --fake result for aerich upgrade and downgrade

* Update readme

* Fix unittest failed because of `db_field_types` changed

* refactor: improve type hints and document

tests/assets/sqlite_migrate/_tests.py

@@ -0,0 +1,75 @@
+import uuid
+
+import pytest
+from models import Foo
+from tortoise.exceptions import IntegrityError
+
+
+@pytest.mark.asyncio
+async def test_allow_duplicate() -> None:
+    await Foo.all().delete()
+    await Foo.create(name="foo")
+    obj = await Foo.create(name="foo")
+    assert (await Foo.all().count()) == 2
+    await obj.delete()
+
+
+@pytest.mark.asyncio
+async def test_unique_is_true() -> None:
+    with pytest.raises(IntegrityError):
+        await Foo.create(name="foo")
+
+
+@pytest.mark.asyncio
+async def test_add_unique_field() -> None:
+    if not await Foo.filter(age=0).exists():
+        await Foo.create(name="0_" + uuid.uuid4().hex, age=0)
+    with pytest.raises(IntegrityError):
+        await Foo.create(name=uuid.uuid4().hex, age=0)
+
+
+@pytest.mark.asyncio
+async def test_drop_unique_field() -> None:
+    name = "1_" + uuid.uuid4().hex
+    await Foo.create(name=name, age=0)
+    assert await Foo.filter(name=name).exists()
+
+
+@pytest.mark.asyncio
+async def test_with_age_field() -> None:
+    name = "2_" + uuid.uuid4().hex
+    await Foo.create(name=name, age=0)
+    obj = await Foo.get(name=name)
+    assert obj.age == 0
+
+
+@pytest.mark.asyncio
+async def test_without_age_field() -> None:
+    name = "3_" + uuid.uuid4().hex
+    await Foo.create(name=name, age=0)
+    obj = await Foo.get(name=name)
+    assert getattr(obj, "age", None) is None
+
+
+@pytest.mark.asyncio
+async def test_m2m_with_custom_through() -> None:
+    from models import FooGroup, Group
+
+    name = "4_" + uuid.uuid4().hex
+    foo = await Foo.create(name=name)
+    group = await Group.create(name=name + "1")
+    await FooGroup.all().delete()
+    await foo.groups.add(group)
+    foo_group = await FooGroup.get(foo=foo, group=group)
+    assert not foo_group.is_active
+
+
+@pytest.mark.asyncio
+async def test_add_m2m_field_after_init_db() -> None:
+    from models import Group
+
+    name = "5_" + uuid.uuid4().hex
+    foo = await Foo.create(name=name)
+    group = await Group.create(name=name + "1")
+    await foo.groups.add(group)
+    assert (await group.users.all().first()) == foo