test: improve coverage across package

errors_test.go

@@ -0,0 +1,45 @@
+package mellaris
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestConfigError_Error(t *testing.T) {
+	e := ConfigError{Field: "port", Err: errors.New("must be > 0")}
+	want := "invalid config: port: must be > 0"
+	if got := e.Error(); got != want {
+		t.Errorf("Error() = %q, want %q", got, want)
+	}
+}
+
+func TestConfigError_Error_NilErr(t *testing.T) {
+	e := ConfigError{Field: "host", Err: nil}
+	want := "invalid config: host: %!s(<nil>)"
+	if got := e.Error(); got != want {
+		t.Errorf("Error() = %q, want %q", got, want)
+	}
+}
+
+func TestConfigError_Unwrap(t *testing.T) {
+	wrapped := errors.New("inner error")
+	e := ConfigError{Field: "field", Err: wrapped}
+	if got := e.Unwrap(); got != wrapped {
+		t.Errorf("Unwrap() = %v, want %v", got, wrapped)
+	}
+}
+
+func TestConfigError_Unwrap_Nil(t *testing.T) {
+	e := ConfigError{Field: "field"}
+	if got := e.Unwrap(); got != nil {
+		t.Errorf("Unwrap() = %v, want nil", got)
+	}
+}
+
+func TestConfigError_ErrorsIs(t *testing.T) {
+	wrapped := errors.New("inner")
+	e := ConfigError{Field: "x", Err: wrapped}
+	if !errors.Is(e, wrapped) {
+		t.Error("errors.Is should find wrapped error")
+	}
+}