client: update some instructions in the README

client/README.md

@@ -30,50 +30,48 @@ Ensure that the following are installed:
 - [venv](https://docs.python.org/3/library/venv.html#module-venv) module.
 - gcc
 
-First, make sure to setup the Zeth dependency in order to generate the
-API files and be able to use the Zeth CLIs:
+First, ensure that the Zeth client has been setup.  (This step is required since the Zeth client setup process includes some code generation).  If this has not already been done, execute the following from the root of the Zecale repository:
 ```console
-$ cd $ZECALE/depends/zeth/client
+$ pushd depends/zeth/client
 $ python -m venv env
 $ source env/bin/activate
 (env)$ make setup
+(env)$ deactivate
+$ popd
 ```
 
-Then, execute the following inside the `client` directory:
+For encapsulation, we suggest creating a Python virtualenv specific to the zecale tools.  The Zeth client code and tools will be installed as an editable package (a reference to, rather than a copy of, the package in `depends/zeth/client`) in this Zecale virtualenv.
 ```console
-$ cd $ZECALE/client
+$ cd client
+$ python -m venv env
+$ source env/bin/activate
 (env)$ make setup
 ```
 
-We assume all further commands described here are executed from within the
-Python virtualenv. To enter the virtualenv from a new terminal, re-run
+We assume all further commands described here are executed from within the Python virtualenv (indicated by the `(env)` prefix to the command prompt) and, unless otherwise stated, in the `client` directory. To enter the virtualenv from a new terminal, re-run the following in the `client` directory.
 ```console
-$ source $ZECALE/depends/zeth/client/env/bin/activate
+$ source env/bin/activate
 ```
+(Alternatively, specify the full path to `client/env/bin/activate` to execute from outside the `client` directory).
 
 ## Execute unit tests
 
+Inside the `client` directory, run
 ```console
 (env)$ make check
 ```
 
 ## Launch a local Ethereum testnet
 
-In order for Zecale to work, it is necessary for the blockchain to support
-BW6-761 arithmetic. As such, we assume below that the smart contracts are
-deployed on an Ethereum testnet that supports BW6-761 precompiled contracts.
-
-To do so, you can start a ganache-cli instance via docker by running:
+Zecale smart contracts require support for BW6-761 arithmetic, via precompiled contracts. A modified version of ganache-cli (which includes such support) can be run from a docker image as follows (note that this should be run in its own terminal instance, from the repo root, and does not require the Python virtualenv to be active):
 ```console
-docker run -ti -p 8545:8545 ghcr.io/clearmatics/ganache-cli --hardfork istanbul --gasLimit 0x3FFFFFFFFFFFF --gasPrice 1 --defaultBalanceEther 90000000000
+$ depends/zeth/scripts/ganache-start
 ```
+(See [Zeth](https://github.com/clearmatics/zeth/) for more information)
 
 ## Execute testing scripts
 
-Once the `aggregator_server` and a custom `ganache-cli` instance are
-running, several scripts can be executed to test the CLIs as well as
-various aspects of the client and the contracts. You can run such tests
-by doing:
+Once the `aggregator_server` and a custom `ganache-cli` instance are running, several scripts can be executed to test the CLIs as well as various aspects of the client and the contracts:
 
 ```console
 (env)$ python test_commands/<script-name> <script-arguments>
@@ -84,7 +82,7 @@ for instance:
 (env)$ python test_commands/test_bw6_761_groth16_contract.py
 ```
 
-Moreover, the CLIs are tested using the following script:
+A fuller integration test for the CLIs can also be executed:
 
 ```console
 (env)$ cd ..
@@ -160,4 +158,3 @@ zecale_dummy_app deploy
 
 For a more comprehensive overview on how to use Zecale with a base
 application, please refer to the [zeth-zecale integration test script](../scripts/test-zeth-zecale).
-