refactor: rpc provider (#6)

- provider now lives on its own
- existing modules need the provider as a param

batch_balance/batch_balance.go

@@ -2,31 +2,17 @@ package balance
 
 import (
 	"github.com/ethereum/go-ethereum/common"
-	"github.com/lmittmann/w3"
+	"github.com/grassrootseconomics/cic-go/provider"
 )
 
 type BatchBalance struct {
-	ethClient     *w3.Client
+	provider      *provider.Provider
 	batchContract common.Address
 }
 
-func NewBatchBalance(rpcEndpoint string, batchContract common.Address) (*BatchBalance, error) {
-	ethClient, err := w3.Dial(rpcEndpoint)
-	if err != nil {
-		return nil, err
-	}
-
+func NewBatchBalance(rpcProvider provider.Provider, batchContract common.Address) (*BatchBalance, error) {
 	return &BatchBalance{
-		ethClient:     ethClient,
+		provider:      &rpcProvider,
 		batchContract: batchContract,
 	}, nil
 }
-
-func (c *BatchBalance) Close() error {
-	err := c.ethClient.Close()
-	if err != nil {
-		return err
-	}
-
-	return nil
-}

batch_balance/batch_balance_test.go

@@ -4,6 +4,7 @@ import (
 	"os"
 	"testing"
 
+	"github.com/grassrootseconomics/cic-go/provider"
 	"github.com/lmittmann/w3"
 )
 
@@ -21,10 +22,15 @@ func TestBatchBalance_Connect(t *testing.T) {
 	name := "Test RPC connection"
 	wantErr := false
 
-	cicnet, _ := NewBatchBalance(conf.rpcProvider, w3.A(conf.batchContract))
+	newProvider, err := provider.NewRpcProvider(conf.rpcProvider)
+	if err != nil {
+		t.Errorf("Creating an rpc instance failed = %v", err)
+	}
+
+	batchBalance, _ := NewBatchBalance(*newProvider, w3.A(conf.batchContract))
 
 	t.Run(name, func(t *testing.T) {
-		if err := cicnet.Close(); (err != nil) != wantErr {
+		if err := batchBalance.provider.EthClient.Close(); (err != nil) != wantErr {
 			t.Errorf("Close() error = %v, wantErr %v", err, wantErr)
 		}
 	})

batch_balance/token_balances.go

@@ -12,7 +12,7 @@ import (
 func (c *BatchBalance) TokensBalance(ctx context.Context, owner common.Address, tokens []common.Address) ([]*big.Int, error) {
 	var balancesResults []*big.Int
 
-	err := c.ethClient.CallCtx(
+	err := c.provider.EthClient.CallCtx(
 		ctx,
 		eth.CallFunc(w3.MustNewFunc("tokensBalance(address owner, address[] contracts)", "uint256[]"), c.batchContract, owner, tokens).Returns(&balancesResults),
 	)

batch_balance/token_balances_test.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/grassrootseconomics/cic-go/provider"
 	"github.com/lmittmann/w3"
 )
 
@@ -35,7 +36,11 @@ func TestBatchBalance_TokensBalance(t *testing.T) {
 		},
 	}
 
-	batchBalance, err := NewBatchBalance(conf.rpcProvider, w3.A(conf.batchContract))
+	newProvider, err := provider.NewRpcProvider(conf.rpcProvider)
+	if err != nil {
+		t.Errorf("Creating an rpc instance failed = %v", err)
+	}
+	batchBalance, err := NewBatchBalance(*newProvider, w3.A(conf.batchContract))
 
 	if err != nil {
 		t.Fatalf("NewBatchBalance error = %v", err)