Add @help edit for modifying existing topics

tests/test_help_topics.py

@@ -202,3 +202,28 @@ async def test_at_help_create_no_args_prompts_name(admin_player):
     await commands.dispatch(admin_player, "@help create")
     output = "".join(c[0][0] for c in admin_player.writer.write.call_args_list)
     assert "name" in output.lower()
+
+
+@pytest.mark.asyncio
+async def test_at_help_edit_unknown_topic(admin_player):
+    await commands.dispatch(admin_player, "@help edit bogus")
+    output = "".join(c[0][0] for c in admin_player.writer.write.call_args_list)
+    assert "not found" in output.lower()
+
+
+@pytest.mark.asyncio
+async def test_at_help_edit_no_args(admin_player):
+    await commands.dispatch(admin_player, "@help edit")
+    output = "".join(c[0][0] for c in admin_player.writer.write.call_args_list)
+    assert "usage" in output.lower()
+
+
+@pytest.mark.asyncio
+async def test_at_help_edit_prompts_title(admin_player):
+    _help_topics["combat"] = HelpTopic(
+        name="combat", body="old body", title="combat primer"
+    )
+    await commands.dispatch(admin_player, "@help edit combat")
+    output = "".join(c[0][0] for c in admin_player.writer.write.call_args_list)
+    # Should show current title as default
+    assert "combat primer" in output