fix(test): cover arg parsing

main.go

@@ -93,9 +93,12 @@ func init() {
 }
 
 func main() {
-	cfg := parseFlags()
-	logger := promlog.New(&cfg.promlogConfig)
+	cfg := parseFlags(os.Args)
+	if cfg == nil {
+		os.Exit(2)
+	}
 
+	logger := promlog.New(&cfg.promlogConfig)
 	level.Info(logger).Log(
 		"msg", "Starting SQL adapter",
 		"build_job", CIBuildJob,
@@ -116,8 +119,8 @@ func main() {
 	}
 }
 
-func parseFlags() *config {
-	a := kingpin.New(filepath.Base(os.Args[0]), "Remote storage adapter")
+func parseFlags(args []string) *config {
+	a := kingpin.New(filepath.Base(args[0]), "Prometheus SQL adapter")
 	a.HelpFlag.Short('h')
 
 	cfg := &config{
@@ -149,11 +152,10 @@ func parseFlags() *config {
 
 	flag.AddFlags(a, &cfg.promlogConfig)
 
-	_, err := a.Parse(os.Args[1:])
+	_, err := a.Parse(args[1:])
 	if err != nil {
-		fmt.Fprintln(os.Stderr, errors.Wrapf(err, "Error parsing commandline arguments"))
-		a.Usage(os.Args[1:])
-		os.Exit(2)
+		fmt.Fprintln(os.Stderr, errors.Wrapf(err, "error parsing commandline arguments"))
+		return nil
 	}
 
 	return cfg

main_test.go

@@ -52,3 +52,56 @@ func TestSendSamples(t *testing.T) {
 		t.Errorf("expected %d samples, got %d", 0, w.SampleCount)
 	}
 }
+
+func TestParseCacheFlags(t *testing.T) {
+	args := []string{
+		"prometheus-sql-adapter",
+		"--pg.cache-size=4",
+	}
+	cfg := parseFlags(args)
+
+	if cfg == nil {
+		t.FailNow()
+	}
+
+	testSize := 4
+	if cfg.Postgres.CacheSize != testSize {
+		t.Errorf("expected postgres cache size to be %d, got %d", testSize, cfg.Postgres.CacheSize)
+	}
+}
+
+func TestParseConnFlags(t *testing.T) {
+	args := []string{
+		"prometheus-sql-adapter",
+		"--pg.max-idle=4",
+		"--pg.max-open=8",
+	}
+	cfg := parseFlags(args)
+
+	if cfg == nil {
+		t.FailNow()
+	}
+
+	testIdle := 4
+	if cfg.Postgres.MaxIdle != testIdle {
+		t.Errorf("expected idle conn limit to be %d, got %d", testIdle, cfg.Postgres.MaxIdle)
+	}
+
+	testOpen := 8
+	if cfg.Postgres.MaxOpen != testOpen {
+		t.Errorf("expected open conn limit to be %d, got %d", testOpen, cfg.Postgres.MaxOpen)
+	}
+}
+
+func TestParseFlagsError(t *testing.T) {
+	args := []string{
+		"some-exec",
+		"--no",
+		"--foop",
+	}
+	cfg := parseFlags(args)
+
+	if cfg != nil {
+		t.Error("args were not expected to parse")
+	}
+}