Internal: user session class

Problem: we often pass 2-3 objects to each function that represent
information on how to connect to the Aleph network:

* the user account
* the API server URL
* the aiohttp session.

This can be simplified to improve the user experience and reduce
the complexity of the SDK.

Solution: introduce a new state class: `UserSession`. This object
is now passed as the first parameter of every public function.
It is initialized with the user account and the API server URL.
It is in charge of configuring and managing the aiohttp session object.

The typical usage of the library now looks like this:

```
account = load_my_account()
api_server = "https://aleph.cloud"  # example
async with UserSession(account=account, api_server=api_server) as session:
  message, status = await create_post(
    session=session,
    ...
  )
```

This enables the following improvements:

* Less clutter in function signatures: all public SDK functions now
  have 1 or 2 fewer arguments.
* The API server URL is now managed when initializing the aiohttp
  session inside the user session object. Implementations can
  simply specify the endpoint URL. Ex:
  `f"{api_server}/api/v0/messages.json` can now be expressed
  as `"/api/v0/messages.json"`.

Breaking changes:

* The signatures of all public functions of the SDK have been
  modified. The user must now initialize the user session object
  and pass it as parameter.

Author: odesenfans

examples/httpgateway.py

@@ -19,6 +19,8 @@
 
 from aiohttp import web
 
+from aleph_client.user_session import UserSession
+
 app = web.Application()
 routes = web.RouteTableDef()
 
@@ -42,13 +44,13 @@ async def source_post(request):
             return web.json_response(
                 {"status": "error", "message": "unauthorized secret"}
             )
-    message, _status = await create_post(
-        app["account"],
-        data,
-        "event",
-        channel=app["channel"],
-        api_server="https://api2.aleph.im",
-    )
+    async with UserSession(account=app["account"], api_server="https://api2.aleph.im") as session:
+        message, _status = await create_post(
+            session=session,
+            post_content=data,
+            post_type="event",
+            channel=app["channel"],
+        )
 
     return web.json_response({"status": "success", "item_hash": message.item_hash})
 

examples/store.py

@@ -7,7 +7,9 @@
 from aleph_client.asynchronous import create_store
 from aleph_client.chains.common import get_fallback_private_key
 from aleph_client.chains.ethereum import ETHAccount
+from aleph_client.conf import settings
 from aleph_client.types import MessageStatus
+from aleph_client.user_session import UserSession
 
 DEFAULT_SERVER = "https://api2.aleph.im"
 
@@ -23,7 +25,7 @@ async def print_output_hash(message: StoreMessage, status: MessageStatus):
 
 
 async def do_upload(account, engine, channel, filename=None, file_hash=None):
-    async with aiohttp.ClientSession() as session:
+    async with UserSession(account=account, api_server=settings.API_HOST) as session:
         print(filename, account.get_address())
         if filename:
             try:
@@ -34,23 +36,21 @@ async def do_upload(account, engine, channel, filename=None, file_hash=None):
                         print("File too big for native STORAGE engine")
                         return
                     message, status = await create_store(
-                        account,
+                        session=session,
                         file_content=content,
                         channel=channel,
                         storage_engine=engine.lower(),
-                        session=session,
                     )
             except IOError:
                 print("File not accessible")
                 raise
 
         elif file_hash:
             message, status = await create_store(
-                account,
+                session=session,
                 file_hash=file_hash,
                 channel=channel,
                 storage_engine=engine.lower(),
-                session=session,
             )
 
         await print_output_hash(message, status)

setup.cfg

@@ -60,6 +60,7 @@ testing =
     pytest
     pytest-cov
     pytest-asyncio
+    pytest-mock
     mypy
     secp256k1
     pynacl
@@ -69,6 +70,7 @@ testing =
     httpx
     requests
     aleph-pytezos==0.1.0
+    types-certifi
     types-setuptools
 mqtt =
     aiomqtt