basic integration test

Signed-off-by: Paul van der Linden <mail@paultjuh.org>

README.md

@@ -285,3 +285,14 @@ GRANT SELECT ON postgres_exporter.pg_stat_statements TO postgres_exporter;
 > ```
 > DATA_SOURCE_NAME=postgresql://postgres_exporter:password@localhost:5432/postgres?sslmode=disable
 > ```
+
+
+## Running the tests
+```
+# Run the unit tests
+make test
+# Start the test database with docker
+docker run -p 5432:5432 -e POSTGRES_DB=circle_test -e POSTGRES_USER=postgres -e POSTGRES_PASSWORD=test -d postgres
+# Run the integration tests
+DATA_SOURCE_NAME='postgresql://postgres:test@localhost:5432/circle_test?sslmode=disable' GOOPTS='-v -tags integration' make test
+```

cmd/postgres_exporter/postgres_exporter_integration_test.go

@@ -162,3 +162,16 @@ func (s *IntegrationSuite) TestExtendQueriesDoesntCrash(c *C) {
 	// scrape the exporter and make sure it works
 	exporter.scrape(ch)
 }
+
+func (s *IntegrationSuite) TestAutoDiscoverDatabases(c *C) {
+	dsn := os.Getenv("DATA_SOURCE_NAME")
+
+	exporter := NewExporter(
+		strings.Split(dsn, ","),
+	)
+	c.Assert(exporter, NotNil)
+
+	dsns := exporter.discoverDatabaseDSNs()
+
+	c.Assert(len(dsns), Equals, 2)
+}