Makes the test also work across pg versions

plugins/postgresql/postgresql_test.go

@@ -29,6 +29,11 @@ func TestPostgresqlGeneratesMetrics(t *testing.T) {
 	err := p.Gather(&acc)
 	require.NoError(t, err)
 
+	availableColumns := make(map[string]bool)
+	for _, col := range p.Servers[0].OrderedColumns {
+		availableColumns[col] = true
+	}
+
 	intMetrics := []string{
 		"xact_commit",
 		"xact_rollback",
@@ -43,6 +48,7 @@ func TestPostgresqlGeneratesMetrics(t *testing.T) {
 		"temp_files",
 		"temp_bytes",
 		"deadlocks",
+		"numbackends",
 	}
 
 	floatMetrics := []string{
@@ -50,13 +56,26 @@ func TestPostgresqlGeneratesMetrics(t *testing.T) {
 		"blk_write_time",
 	}
 
+	metricsCounted := 0
+
 	for _, metric := range intMetrics {
-		assert.True(t, acc.HasIntValue(metric))
+		_, ok := availableColumns[metric]
+		if ok {
+			assert.True(t, acc.HasIntValue(metric))
+			metricsCounted++
+		}
 	}
 
 	for _, metric := range floatMetrics {
-		assert.True(t, acc.HasFloatValue(metric))
+		_, ok := availableColumns[metric]
+		if ok {
+			assert.True(t, acc.HasFloatValue(metric))
+			metricsCounted++
+		}
 	}
+
+	assert.True(t, metricsCounted > 0)
+	assert.Equal(t, len(availableColumns) - len(p.IgnoredColumns()), metricsCounted)
 }
 
 func TestPostgresqlTagsMetricsWithDatabaseName(t *testing.T) {