From 94a812d98f8d22c67f85faf062f95cf08ebf2c7a Mon Sep 17 00:00:00 2001
From: Bryan Boreham <bjboreham@gmail.com>
Date: Wed, 22 Oct 2014 18:24:02 +0100
Subject: [PATCH] Factor out error type checks

---
 server/http_test.go     |  4 +---
 server/testing_utils.go | 15 +++++++++++++++
 server/zone_test.go     | 16 ++++------------
 3 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/server/http_test.go b/server/http_test.go
index a53792fe..fe2b1c04 100644
--- a/server/http_test.go
+++ b/server/http_test.go
@@ -69,9 +69,7 @@ func TestHttp(t *testing.T) {
 
 	// Check that the address is not there now.
 	_, err = zone.MatchLocal(success_test_name)
-	if _, ok := err.(LookupError); !ok {
-		t.Fatal(err)
-	}
+	assertErrorType(t, err, (*LookupError)(nil), "nonexistent lookup")
 
 	// Delete the address again, it should accept this
 	resp, err = genForm("DELETE", addr_url, nil)
diff --git a/server/testing_utils.go b/server/testing_utils.go
index c5695c93..53dab804 100644
--- a/server/testing_utils.go
+++ b/server/testing_utils.go
@@ -1,6 +1,7 @@
 package weavedns
 
 import (
+	"reflect"
 	"testing"
 )
 
@@ -15,3 +16,17 @@ func assertStatus(t *testing.T, got int, wanted int, desc string) {
 		t.Fatalf("Expected %s %d but got %d", desc, wanted, got)
 	}
 }
+
+func assertErrorInterface(t *testing.T, got interface{}, wanted interface{}, desc string) {
+	got_t, wanted_t := reflect.TypeOf(got), reflect.TypeOf(wanted).Elem()
+	if !got_t.Implements(wanted_t) {
+		t.Fatalf("Expected %s but got %s (%s)", wanted_t.String(), got_t.String(), desc)
+	}
+}
+
+func assertErrorType(t *testing.T, got interface{}, wanted interface{}, desc string) {
+	got_t, wanted_t := reflect.TypeOf(got), reflect.TypeOf(wanted).Elem()
+	if got_t != wanted_t {
+		t.Fatalf("Expected %s but got %s (%s)", wanted_t.String(), got_t.String(), desc)
+	}
+}
diff --git a/server/zone_test.go b/server/zone_test.go
index 236b7518..6fe44094 100644
--- a/server/zone_test.go
+++ b/server/zone_test.go
@@ -30,9 +30,7 @@ func TestZone(t *testing.T) {
 
 	// Now try to add the same address again
 	err = zone.AddRecord(container_id, success_test_name, ip, weave_ip, subnet)
-	if _, ok := err.(DuplicateError); !ok {
-		t.Fatal(err)
-	}
+	assertErrorType(t, err, (*DuplicateError)(nil), "duplicate add")
 
 	// Now delete the record
 	err = zone.DeleteRecord(container_id, weave_ip)
@@ -40,15 +38,11 @@ func TestZone(t *testing.T) {
 
 	// Check that the address is not there now.
 	_, err = zone.MatchLocal(success_test_name)
-	if _, ok := err.(LookupError); !ok {
-		t.Fatal("Unexpected result when deleting record", success_test_name, err)
-	}
+	assertErrorType(t, err, (*LookupError)(nil), "after deleting record")
 
 	// Delete a record that isn't there
 	err = zone.DeleteRecord(container_id, net.ParseIP("0.0.0.0"))
-	if _, ok := err.(LookupError); !ok {
-		t.Fatal("Expected a LookupError when deleting a record that doesn't exist")
-	}
+	assertErrorType(t, err, (*LookupError)(nil), "when deleting record that doesn't exist")
 }
 
 func TestDeleteFor(t *testing.T) {
@@ -72,7 +66,5 @@ func TestDeleteFor(t *testing.T) {
 
 	err = zone.DeleteRecordsFor(id)
 	_, err = zone.MatchLocal(name)
-	if _, ok := err.(LookupError); !ok {
-		t.Fatal("Expected no results after deleting records for ident")
-	}
+	assertErrorType(t, err, (*LookupError)(nil), "after deleting records for ident")
 }