config: add Duration test coverage and fix error wrapping

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I5c08e63297f90acdedd9744de904c36b6a6a6964

internal/config/config.go

@@ -21,7 +21,7 @@ func (d *Duration) UnmarshalYAML(value *yaml.Node) error {
 		// Try decoding as a raw int64 (nanoseconds) as fallback.
 		var ns int64
 		if err2 := value.Decode(&ns); err2 != nil {
-			return fmt.Errorf("cannot unmarshal duration: %w", err)
+			return fmt.Errorf("cannot unmarshal duration (tried string: %v): %w", err, err2)
 		}
 		d.Duration = time.Duration(ns)
 		return nil

internal/config/config_test.go

@@ -3,6 +3,7 @@ package config_test
 import (
 	"os"
 	"testing"
+	"time"
 
 	"notashelf.dev/ncro/internal/config"
 )
@@ -61,3 +62,53 @@ func TestEnvOverride(t *testing.T) {
 		t.Errorf("env override listen = %q, want :1234", cfg.Server.Listen)
 	}
 }
+
+func TestDurationParsing(t *testing.T) {
+	yamlContent := `
+server:
+  listen: ":8080"
+  read_timeout: 30s
+  write_timeout: 1m
+cache:
+  ttl: 2h
+mesh:
+  gossip_interval: 45s
+`
+	f, _ := os.CreateTemp("", "ncro-dur-*.yaml")
+	defer os.Remove(f.Name())
+	f.WriteString(yamlContent)
+	f.Close()
+
+	cfg, err := config.Load(f.Name())
+	if err != nil {
+		t.Fatalf("Load error: %v", err)
+	}
+	if cfg.Server.ReadTimeout.Duration != 30*time.Second {
+		t.Errorf("read_timeout = %v, want 30s", cfg.Server.ReadTimeout.Duration)
+	}
+	if cfg.Server.WriteTimeout.Duration != time.Minute {
+		t.Errorf("write_timeout = %v, want 1m", cfg.Server.WriteTimeout.Duration)
+	}
+	if cfg.Cache.TTL.Duration != 2*time.Hour {
+		t.Errorf("ttl = %v, want 2h", cfg.Cache.TTL.Duration)
+	}
+	if cfg.Mesh.GossipInterval.Duration != 45*time.Second {
+		t.Errorf("gossip_interval = %v, want 45s", cfg.Mesh.GossipInterval.Duration)
+	}
+}
+
+func TestInvalidDuration(t *testing.T) {
+	yamlContent := `
+server:
+  read_timeout: "bananas"
+`
+	f, _ := os.CreateTemp("", "ncro-bad-*.yaml")
+	defer os.Remove(f.Name())
+	f.WriteString(yamlContent)
+	f.Close()
+
+	_, err := config.Load(f.Name())
+	if err == nil {
+		t.Error("expected error for invalid duration string, got nil")
+	}
+}