Prevent panic in tests whose queries fail

Some tests were ignoring errors and proceeding to inspect query
results, causing failure via panic. Instead, fail these tests via more
explicit assertions.

tests/net_test.go

@@ -37,7 +37,9 @@ func TestConnectionCreation(t *testing.T) {
 		e := fargo.NewConnFromConfig(cfg)
 		apps, err := e.GetApps()
 		So(err, ShouldBeNil)
-		So(len(apps["EUREKA"].Instances), ShouldEqual, 2)
+		app := apps["EUREKA"]
+		So(app, ShouldNotBeNil)
+		So(len(app.Instances), ShouldEqual, 2)
 	})
 }
 
@@ -46,11 +48,15 @@ func TestGetApps(t *testing.T) {
 	for _, j := range []bool{false, true} {
 		e.UseJson = j
 		Convey("Pull applications", t, func() {
-			a, _ := e.GetApps()
-			So(len(a["EUREKA"].Instances), ShouldEqual, 2)
+			apps, err := e.GetApps()
+			So(err, ShouldBeNil)
+			app := apps["EUREKA"]
+			So(app, ShouldNotBeNil)
+			So(len(app.Instances), ShouldEqual, 2)
 		})
 		Convey("Pull single application", t, func() {
 			a, _ := e.GetApp("EUREKA")
+			So(a, ShouldNotBeNil)
 			So(len(a.Instances), ShouldEqual, 2)
 			for _, ins := range a.Instances {
 				So(ins.IPAddr, ShouldBeIn, []string{"172.17.0.2", "172.17.0.3"})