Adds some supplemental tests for RPC "no leader" retries.

This adds some extra tests for #2175.

consul/rpc_test.go

@@ -0,0 +1,72 @@
+package consul
+
+import (
+	"os"
+	"testing"
+	"time"
+
+	"github.com/hashicorp/consul/consul/structs"
+	"github.com/hashicorp/consul/testutil"
+	"github.com/hashicorp/net-rpc-msgpackrpc"
+)
+
+func TestRPC_NoLeader_Fail(t *testing.T) {
+	dir1, s1 := testServerWithConfig(t, func(c *Config) {
+		c.RPCHoldTimeout = 1 * time.Millisecond
+	})
+	defer os.RemoveAll(dir1)
+	defer s1.Shutdown()
+	codec := rpcClient(t, s1)
+	defer codec.Close()
+
+	arg := structs.RegisterRequest{
+		Datacenter: "dc1",
+		Node:       "foo",
+		Address:    "127.0.0.1",
+	}
+	var out struct{}
+
+	// Make sure we eventually fail with a no leader error, which we should
+	// see given the short timeout.
+	err := msgpackrpc.CallWithCodec(codec, "Catalog.Register", &arg, &out)
+	if err.Error() != structs.ErrNoLeader.Error() {
+		t.Fatalf("bad: %v", err)
+	}
+
+	// Now make sure it goes through.
+	testutil.WaitForLeader(t, s1.RPC, "dc1")
+	err = msgpackrpc.CallWithCodec(codec, "Catalog.Register", &arg, &out)
+	if err != nil {
+		t.Fatalf("bad: %v", err)
+	}
+}
+
+func TestRPC_NoLeader_Retry(t *testing.T) {
+	dir1, s1 := testServerWithConfig(t, func(c *Config) {
+		c.RPCHoldTimeout = 10 * time.Second
+	})
+	defer os.RemoveAll(dir1)
+	defer s1.Shutdown()
+	codec := rpcClient(t, s1)
+	defer codec.Close()
+
+	arg := structs.RegisterRequest{
+		Datacenter: "dc1",
+		Node:       "foo",
+		Address:    "127.0.0.1",
+	}
+	var out struct{}
+
+	// This isn't sure-fire but tries to check that we don't have a
+	// leader going into the RPC, so we exercise the retry logic.
+	if ok, _ := s1.getLeader(); ok {
+		t.Fatalf("should not have a leader yet")
+	}
+
+	// The timeout is long enough to ride out any reasonable leader
+	// election.
+	err := msgpackrpc.CallWithCodec(codec, "Catalog.Register", &arg, &out)
+	if err != nil {
+		t.Fatalf("bad: %v", err)
+	}
+}