feat(signers): make Signer on Client optional (#34)

This allows using Contract either in read-only mode (e.g. for fetching data/events)
or for using the accounts on the node as senders

ethers-contract/src/factory.rs

@@ -148,6 +148,7 @@ where
 
         // create the tx object. Since we're deploying a contract, `to` is `None`
         let tx = TransactionRequest {
+            from: Some(self.client.address()),
             to: None,
             data: Some(data),
             ..Default::default()

ethers-contract/tests/contract.rs

@@ -6,8 +6,14 @@ pub use common::*;
 #[cfg(not(feature = "celo"))]
 mod eth_tests {
     use super::*;
-    use ethers::{providers::StreamExt, types::Address, utils::Ganache};
+    use ethers::{
+        providers::{Http, Provider, StreamExt},
+        signers::Client,
+        types::Address,
+        utils::Ganache,
+    };
     use serial_test::serial;
+    use std::convert::TryFrom;
 
     #[tokio::test]
     #[serial]
@@ -133,6 +139,35 @@ mod eth_tests {
             assert_eq!(log.new_value, i.to_string());
         }
     }
+
+    #[tokio::test]
+    #[serial]
+    async fn signer_on_node() {
+        let (abi, bytecode) = compile();
+        let provider = Provider::<Http>::try_from("http://localhost:8545").unwrap();
+        let deployer = "3cDB3d9e1B74692Bb1E3bb5fc81938151cA64b02"
+            .parse::<Address>()
+            .unwrap();
+        let client = Client::from(provider).with_sender(deployer);
+        let (_ganache, contract) = deploy(&client, abi, bytecode).await;
+
+        // make a call without the signer
+        let _tx = contract
+            .method::<_, H256>("setValue", "hi".to_owned())
+            .unwrap()
+            .send()
+            .await
+            .unwrap()
+            .await
+            .unwrap();
+        let value: String = contract
+            .method::<_, String>("getValue", ())
+            .unwrap()
+            .call()
+            .await
+            .unwrap();
+        assert_eq!(value, "hi");
+    }
 }
 
 #[cfg(feature = "celo")]

ethers-signers/src/client.rs

@@ -71,7 +71,7 @@ use thiserror::Error;
 /// [`Provider`]: ethers_providers::Provider
 pub struct Client<P, S> {
     pub(crate) provider: Provider<P>,
-    pub(crate) signer: S,
+    pub(crate) signer: Option<S>,
     pub(crate) address: Address,
 }
 
@@ -102,7 +102,7 @@ where
         let address = signer.address();
         Client {
             provider,
-            signer,
+            signer: Some(signer),
             address,
         }
     }
@@ -110,7 +110,11 @@ where
     /// Signs a message with the internal signer, or if none is present it will make a call to
     /// the connected node's `eth_call` API.
     pub async fn sign_message<T: Into<Bytes>>(&self, msg: T) -> Result<Signature, ClientError> {
-        Ok(self.signer.sign_message(msg.into()))
+        Ok(if let Some(ref signer) = self.signer {
+            signer.sign_message(msg.into())
+        } else {
+            self.provider.sign(msg, &self.address()).await?
+        })
     }
 
     /// Signs and broadcasts the transaction. The optional parameter `block` can be passed so that
@@ -131,11 +135,13 @@ where
         // fill any missing fields
         self.fill_transaction(&mut tx, block).await?;
 
-        // sign the transaction with the network
-        let signed_tx = self.signer.sign_transaction(tx).map_err(Into::into)?;
-
-        // broadcast it
-        Ok(self.provider.send_raw_transaction(&signed_tx).await?)
+        // sign the transaction and broadcast it
+        Ok(if let Some(ref signer) = self.signer {
+            let signed_tx = signer.sign_transaction(tx).map_err(Into::into)?;
+            self.provider.send_raw_transaction(&signed_tx).await?
+        } else {
+            self.provider.send_transaction(tx).await?
+        })
     }
 
     async fn fill_transaction(
@@ -166,7 +172,7 @@ where
 
     /// Returns the client's address
     pub fn address(&self) -> Address {
-        self.signer.address()
+        self.address
     }
 
     /// Returns a reference to the client's provider
@@ -175,8 +181,8 @@ where
     }
 
     /// Returns a reference to the client's signer
-    pub fn signer(&self) -> &S {
-        &self.signer
+    pub fn signer(&self) -> Option<&S> {
+        self.signer.as_ref()
     }
 
     /// Sets the signer and returns a mutable reference to self so that it can be used in chained
@@ -188,7 +194,8 @@ where
         P: Clone,
     {
         let mut this = self.clone();
-        this.signer = signer;
+        this.address = signer.address();
+        this.signer = Some(signer);
         this
     }
 
@@ -204,6 +211,14 @@ where
         this.provider = provider;
         this
     }
+
+    /// Sets the address which will be used for interacting with the blockchain.
+    /// Useful if no signer is set and you want to specify a default sender for
+    /// your transactions
+    pub fn with_sender<T: Into<Address>>(mut self, address: T) -> Self {
+        self.address = address.into();
+        self
+    }
 }
 
 /// Calls the future if `item` is None, otherwise returns a `futures::ok`
@@ -228,3 +243,13 @@ impl<P, S> Deref for Client<P, S> {
         &self.provider
     }
 }
+
+impl<P: JsonRpcClient, S> From<Provider<P>> for Client<P, S> {
+    fn from(provider: Provider<P>) -> Self {
+        Self {
+            provider,
+            signer: None,
+            address: Address::zero(),
+        }
+    }
+}

ethers-signers/src/wallet.rs

@@ -119,7 +119,7 @@ impl Wallet {
         let address = self.address();
         Client {
             address,
-            signer: self,
+            signer: Some(self),
             provider,
         }
     }