add support for cache purge requests via GET from admin or PURGE method. PURGE doesn't quite work yet, so we skip testing that one.

test/nginx_system_test.sh

@@ -250,6 +250,12 @@ else
   exit 4
 fi
 
+# check_stat in system_test_helpers.sh needs to know whether statstistics are
+# enabled, which is always the case for ngx_pagespeed.
+statistics_enabled=1
+CACHE_FLUSH_TEST="on"
+CACHE_PURGE_METHODS="GET"   # PURGE is not working yet.
+
 # run generic system tests
 SYSTEM_TEST_FILE="$MOD_PAGESPEED_DIR/src/net/instaweb/system/system_test.sh"
 

test/pagespeed_test.conf.template

@@ -968,6 +968,21 @@ http {
     pagespeed InPlaceResourceOptimization on;
   }
 
+  server {
+    listen @@SECONDARY_PORT@@;
+    server_name purge.example.com;
+
+    # Test purging individual URLs without flushing the entire metadata cache.
+    pagespeed EnableCachePurge on;
+
+    pagespeed PurgeMethod PURGE;
+    root "@@SERVER_ROOT@@";
+    pagespeed FileCachePath "@@FILE_CACHE@@_purge";
+    pagespeed DisableFilters add_instrumentation;
+    pagespeed RewriteLevel PassThrough;
+    pagespeed EnableFilters rewrite_css;
+  }
+
   server {
     listen       @@PRIMARY_PORT@@;
     server_name  localhost;