fix: registry, update, file duplicate series, config key and error reporting (#2509)

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Jan-Otto Kröpke <mail@jkroepke.de>

internal/config/config_test.go

@@ -20,11 +20,18 @@ package config_test
 import (
 	"os"
 	"path/filepath"
+	"reflect"
+	"regexp"
+	"slices"
+	"strings"
 	"testing"
+	"time"
 
 	"github.com/alecthomas/kingpin/v2"
 	"github.com/prometheus-community/windows_exporter/internal/config"
+	"github.com/prometheus-community/windows_exporter/pkg/collector"
 	"github.com/stretchr/testify/require"
+	"go.yaml.in/yaml/v3"
 )
 
 func TestParseConfigFile(t *testing.T) {
@@ -91,6 +98,105 @@ func TestNewConfigFileResolver(t *testing.T) {
 	})
 }
 
+// TestNewConfigFileResolverCollectorFlags verifies that every collector flag can
+// be set from the configuration file: the nested key derived from the flag name
+// must exist in collector.Config, pass the strict validation, and be bound back
+// to the same flag.
+func TestNewConfigFileResolverCollectorFlags(t *testing.T) {
+	t.Parallel()
+
+	app := kingpin.New("test", "test")
+	collector.NewWithFlags(app)
+
+	for _, flag := range app.Model().Flags {
+		// collector.exchange.list prints the available sub-collectors and exits;
+		// it is not a configuration option.
+		if !strings.HasPrefix(flag.Name, "collector.") || flag.Name == "collector.exchange.list" {
+			continue
+		}
+
+		t.Run(flag.Name, func(t *testing.T) {
+			t.Parallel()
+
+			keys := strings.Split(flag.Name, ".")
+
+			field, ok := configFieldType(reflect.TypeFor[collector.Config](), keys[1:])
+			require.True(t, ok, "collector.Config has no field with the yaml path %s", flag.Name)
+
+			value, want := sampleConfigValue(t, field)
+
+			contents := value
+			for _, key := range slices.Backward(keys) {
+				contents = map[string]any{key: contents}
+			}
+
+			data, err := yaml.Marshal(contents)
+			require.NoError(t, err)
+
+			path := filepath.Join(t.TempDir(), "config.yaml")
+			require.NoError(t, os.WriteFile(path, data, 0o600))
+
+			resolver, err := config.NewConfigFileResolver(path)
+			require.NoError(t, err, "config:\n%s", data)
+
+			bindApp := kingpin.New("test", "test")
+			collector.NewWithFlags(bindApp)
+
+			require.NoError(t, resolver.Bind(bindApp, nil))
+			require.Equal(t, []string{want}, bindApp.GetFlag(flag.Name).Model().Default)
+		})
+	}
+}
+
+// configFieldType returns the type of the struct field reached by following
+// the yaml tags in keys, starting at typ.
+func configFieldType(typ reflect.Type, keys []string) (reflect.Type, bool) {
+	if len(keys) == 0 {
+		return typ, true
+	}
+
+	if typ.Kind() != reflect.Struct {
+		return nil, false
+	}
+
+	for field := range typ.Fields() {
+		if name, _, _ := strings.Cut(field.Tag.Get("yaml"), ","); name == keys[0] {
+			return configFieldType(field.Type, keys[1:])
+		}
+	}
+
+	return nil, false
+}
+
+// sampleConfigValue returns a configuration file value that decodes into typ,
+// together with the flag value the resolver flattens it to.
+func sampleConfigValue(t *testing.T, typ reflect.Type) (any, string) {
+	t.Helper()
+
+	switch {
+	case typ == reflect.TypeFor[time.Duration]():
+		return "1m", "1m"
+	case typ == reflect.TypeFor[*regexp.Regexp]():
+		return "test", "test"
+	}
+
+	switch typ.Kind() {
+	case reflect.Bool:
+		return true, "true"
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+		reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return 1, "1"
+	case reflect.Slice:
+		return []string{"test"}, "test"
+	case reflect.String:
+		return "test", "test"
+	default:
+		t.Fatalf("no sample configuration value for type %s", typ)
+
+		return nil, ""
+	}
+}
+
 func TestParse(t *testing.T) {
 	t.Parallel()