base: make TestValidateAddrs work without a network connection

Looking up an invalid host name may result in a different error
depending on whether the test has access to a network connection or not.
This patch modifies the test to catch that.

Fixes: #109052

Release note: None

Author: arulajmani

pkg/base/addr_validation_test.go

@@ -64,12 +64,17 @@ func TestValidateAddrs(t *testing.T) {
 		t.Fatal("expected port resolution failure, got no error")
 	}
 	portExpectedErr := err.Error()
-	// For the host name resolution error we can reliably expect "no such host"
-	// below, but before we test anything we need to ensure we indeed have
-	// a reliably non-resolvable host name.
-	_, err = net.DefaultResolver.LookupIPAddr(context.Background(), "nonexistent.example.com")
-	if err == nil {
-		t.Fatal("expected host resolution failure, got no error")
+	// ValidateAddrs uses a net.DefaultResolver for host name resolution.
+	// Normally, when given a non-existent host name, we expect it to return a
+	// "no such host" error. However, it may return a different error if there is
+	// no network access. See
+	// https://github.com/cockroachdb/cockroach/issues/109052.
+	noSuchHostErr := func(host string) string {
+		_, err := net.DefaultResolver.LookupIPAddr(context.Background(), host)
+		if err == nil { // the supplied host is expected to be reliably non-resolvable
+			t.Fatal("expected host resolution failure, got no error")
+		}
+		return err.Error()
 	}
 
 	// The test cases.
@@ -149,8 +154,8 @@ func TestValidateAddrs(t *testing.T) {
 		{addrs{"localhost:-1231", "", "", "", "", ""}, "invalid port", addrs{}},
 		{addrs{"localhost:nonexistent", "", "", "", "", ""}, portExpectedErr, addrs{}},
 		// Invalid address.
-		{addrs{"nonexistent.example.com:26257", "", "", "", "", ""}, "no such host", addrs{}},
-		{addrs{"333.333.333.333:26257", "", "", "", "", ""}, "no such host", addrs{}},
+		{addrs{"nonexistent.example.com:26257", "", "", "", "", ""}, noSuchHostErr("nonexistent.example.com"), addrs{}},
+		{addrs{"333.333.333.333:26257", "", "", "", "", ""}, noSuchHostErr("333.333.333.333"), addrs{}},
 	}
 
 	for i, test := range testData {