Add failing double precision roundtrip test

Add a failing test for roundtripping large double precision values.
This test will fail with the default extra_float_digits.

Reproduces brianc#730

Author: sehrope

test/integration/client/float-precision-tests.js

@@ -0,0 +1,35 @@
+var async = require('async');
+var helper = require(__dirname + '/../test-helper');
+var exec = require('child_process').exec;
+
+var floatTestVals = [
+  '0',
+  '1',
+  '100',
+  '123.456',
+  '123456.123456',
+  '2099999997689999',
+  '2099999997690000',
+  '2099999997690001'
+]
+
+helper.pg.connect(helper.config, function(err, client, done) {
+  assert.isNull(err);
+
+  function testFloatRoundTrip(val, cb) {
+    test('float round trip val=' + val, function() {
+      var sql = 'SELECT $1::float8 AS val'
+      client.query(sql, [val], function(err, result){
+        assert.isNull(err);
+        assert.equal(result.rows[0].val, val);
+        cb(null);
+      });
+    });
+  };
+
+  async.eachSeries(floatTestVals, testFloatRoundTrip, function(err, results){
+    assert.isNull(err || null);
+    done();
+    helper.pg.end();
+  });
+});