feat(go-config): multi-format codecs, envc CLI, fixtures, ASRs

- Module github.com/eslider/go-config with env/yaml/json/ini packages
- internal: source, keymap, merge, structconv, bytesutil
- cmd/envc: convert, get, merge
- docs/asr ASR-0001..0008, README/CHANGELOG/AGENTS refresh
- golangci-lint v2 config; tests + fixtures

Co-authored-by: Cursor <cursoragent@cursor.com>

yaml/codec_test.go

@@ -0,0 +1,78 @@
+package yaml
+
+import (
+	"context"
+	"reflect"
+	"testing"
+
+	"github.com/eslider/go-config/internal/keymap"
+	"github.com/eslider/go-config/internal/merge"
+	"github.com/eslider/go-config/testfixtures"
+	yaml3 "gopkg.in/yaml.v3"
+)
+
+func TestCodec_IdentityFixture(t *testing.T) {
+	c := New(WithBytes(testfixtures.Load(t, "identity", "service.yaml")))
+	m, err := c.Map(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	exp, err := loadExpectedMap(t)
+	if err != nil {
+		t.Fatal(err)
+	}
+	keymap.Walk(exp, keymap.LowerAlnum)
+	if !mapsEqual(m, exp) {
+		t.Fatalf("map mismatch\n got: %#v\n exp: %#v", m, exp)
+	}
+}
+
+func TestCodec_MergeReplaceSlices(t *testing.T) {
+	c := New(
+		WithBytes(testfixtures.Load(t, "merge", "defaults.yaml")),
+		WithBytes(testfixtures.Load(t, "merge", "overlay.yaml")),
+	)
+	got, err := c.Map(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	exp := map[string]any{}
+	if err := yaml3.Unmarshal(testfixtures.Load(t, "merge", "expected-replace.yaml"), &exp); err != nil {
+		t.Fatal(err)
+	}
+	keymap.Walk(exp, keymap.LowerAlnum)
+	if !mapsEqual(got, exp) {
+		t.Fatalf("merge mismatch\n got: %#v\n exp: %#v", got, exp)
+	}
+}
+
+func TestCodec_MergeConcatSlices(t *testing.T) {
+	c := New(
+		WithBytes(testfixtures.Load(t, "merge", "defaults.yaml")),
+		WithBytes(testfixtures.Load(t, "merge", "overlay.yaml")),
+		WithSliceMerge(merge.Concat),
+	)
+	got, err := c.Map(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	exp := map[string]any{}
+	if err := yaml3.Unmarshal(testfixtures.Load(t, "merge", "expected-concat.yaml"), &exp); err != nil {
+		t.Fatal(err)
+	}
+	keymap.Walk(exp, keymap.LowerAlnum)
+	if !mapsEqual(got, exp) {
+		t.Fatalf("concat mismatch\n got: %#v\n exp: %#v", got, exp)
+	}
+}
+
+func loadExpectedMap(t *testing.T) (map[string]any, error) {
+	t.Helper()
+	var m map[string]any
+	err := yaml3.Unmarshal(testfixtures.Load(t, "identity", "service.yaml"), &m)
+	return m, err
+}
+
+func mapsEqual(a, b map[string]any) bool {
+	return reflect.DeepEqual(a, b)
+}