Count only test query itself (#87)

* Count only test query itself

This breaks more obviously in PostgreSQL 10 (https://wiki.postgresql.org/wiki/New_in_postgres_10#Significant_Expansion_of_Wait_Events_in_pg_stat_activity).

* Fix query counting for PostgreSQL 9.1

Author: charmander

test/sizing.js

@@ -33,11 +33,17 @@ describe('pool size of 1', () => {
 
   it('can only send 1 query at a time', co.wrap(function * () {
     const pool = new Pool({ max: 1 })
-    const queries = _.times(20, (i) => {
-      return pool.query('SELECT COUNT(*) as counts FROM pg_stat_activity')
-    })
+
+    // the query text column name changed in PostgreSQL 9.2
+    const versionResult = yield pool.query('SHOW server_version_num')
+    const version = parseInt(versionResult.rows[0].server_version_num, 10)
+    const queryColumn = version < 90200 ? 'current_query' : 'query'
+
+    const queryText = 'SELECT COUNT(*) as counts FROM pg_stat_activity WHERE ' + queryColumn + ' = $1'
+    const queries = _.times(20, () =>
+      pool.query(queryText, [queryText]))
     const results = yield Promise.all(queries)
-    const counts = results.map(res => parseInt(res.rows[0].counts), 10)
+    const counts = results.map(res => parseInt(res.rows[0].counts, 10))
     expect(counts).to.eql(_.times(20, i => 1))
     return yield pool.end()
   }))