Close callback contexts when callbacks panic

internal/engine/callback_panic_test.go

@@ -0,0 +1,73 @@
+package engine
+
+import (
+	"errors"
+	"testing"
+)
+
+func capturePanic(call func()) (recovered any) {
+	defer func() { recovered = recover() }()
+	call()
+	return nil
+}
+
+func requirePanicValue(t *testing.T, want any, call func()) {
+	t.Helper()
+	if got := capturePanic(call); got != want {
+		t.Fatalf("panic = %#v, want %#v", got, want)
+	}
+}
+
+func TestCallbackContextsCloseWhenCallbacksPanic(t *testing.T) {
+	type config struct {
+		Value   string `yaml:"value"`
+		Version string `yaml:"version"`
+	}
+
+	t.Run("resolution", func(t *testing.T) {
+		sentinel := errors.New("resolution panic sentinel")
+		var retained *Resolution
+		got := capturePanic(func() {
+			_, _ = testLoad[config](NoSource(), Options[config]{Definition: Definition[config]{Resolve: func(_ *config, resolution *Resolution) error {
+				retained = resolution
+				panic(sentinel)
+			}}})
+		})
+		if got != sentinel {
+			t.Fatalf("callback panic = %#v, want original sentinel", got)
+		}
+		requirePanicValue(t, closedCallbackContextMessage, func() { retained.IsExplicit(Keys("value")) })
+	})
+
+	t.Run("validation", func(t *testing.T) {
+		sentinel := errors.New("validation panic sentinel")
+		var retained *Validation
+		got := capturePanic(func() {
+			_, _ = testLoad[config](NoSource(), Options[config]{Definition: Definition[config]{Validate: func(_ *config, validation *Validation) {
+				retained = validation
+				panic(sentinel)
+			}}})
+		})
+		if got != sentinel {
+			t.Fatalf("callback panic = %#v, want original sentinel", got)
+		}
+		requirePanicValue(t, closedCallbackContextMessage, func() { retained.Error(Keys("value"), "too late") })
+	})
+
+	t.Run("version", func(t *testing.T) {
+		sentinel := errors.New("version panic sentinel")
+		var retained *Validation
+		got := capturePanic(func() {
+			_, _ = testLoad[config](Bytes("version.yml", []byte("version: v1\n")), Options[config]{Definition: Definition[config]{
+				Version: &VersionRule{Path: Keys("version"), Check: func(_ Version, validation *Validation) error {
+					retained = validation
+					panic(sentinel)
+				}},
+			}})
+		})
+		if got != sentinel {
+			t.Fatalf("callback panic = %#v, want original sentinel", got)
+		}
+		requirePanicValue(t, closedCallbackContextMessage, func() { retained.Warning(Keys("version"), "too late") })
+	})
+}