add unit test for existing extra

Author: Emyrk

types/diagnostics.go

@@ -10,13 +10,13 @@ type DiagnosticExtra struct {
 	Code string `json:"code"`
 
 	// If there was a previous extra, store it here for unwrapping.
-	wrapped any
+	Wrapped any
 }
 
 var _ hcl.DiagnosticExtraUnwrapper = DiagnosticExtra{}
 
 func (e DiagnosticExtra) UnwrapDiagnosticExtra() interface{} {
-	return e.wrapped
+	return e.Wrapped
 }
 
 func ExtractDiagnosticExtra(diag *hcl.Diagnostic) DiagnosticExtra {
@@ -29,16 +29,17 @@ func SetDiagnosticExtra(diag *hcl.Diagnostic, extra DiagnosticExtra) {
 	existing, ok := hcl.DiagnosticExtra[DiagnosticExtra](diag)
 	if ok {
 		// If an existing extra is present, we will keep the underlying
-		// wrapped. This is not perfect, as any parents are lost.
+		// Wrapped. This is not perfect, as any parents are lost.
 		// So try to avoid calling 'SetDiagnosticExtra' more than once.
-		extra.wrapped = existing.wrapped
+		// TODO: Fix this so we maintain the parents too. Maybe use a pointer?
+		extra.Wrapped = existing.Wrapped
 		diag.Extra = extra
 		return
 	}
 
 	// Maintain any existing extra fields.
 	if diag.Extra != nil {
-		extra.wrapped = diag.Extra
+		extra.Wrapped = diag.Extra
 	}
 	diag.Extra = extra
 }

types/diagnostics_test.go

@@ -35,6 +35,44 @@ func TestDiagnosticExtra(t *testing.T) {
 	require.Equal(t, "bazz", extra.Code)
 }
 
+// TestDiagnosticExtraExisting is a test case where the DiagnosticExtra
+// is already set in the wrapped chain of diagnostics.
+// The `parent` wrapped is lost here, so calling `SetDiagnosticExtra` is
+// lossy. In practice, we only call this once, so it's ok.
+// TODO: Fix SetDiagnosticExtra to maintain the parents
+//  if the DiagnosticExtra already exists in the chain.
+func TestDiagnosticExtraExisting(t *testing.T) {
+	diag := &hcl.Diagnostic{
+		Severity: hcl.DiagWarning,
+		Summary:  "Some summary",
+		Detail:   "Some detail",
+		// parent -> existing -> child
+		Extra: wrappedDiagnostic{
+			name: "parent",
+			wrapped: types.DiagnosticExtra{
+				Code: "foobar",
+				Wrapped: wrappedDiagnostic{
+					name:    "child",
+					wrapped: nil,
+				},
+			},
+		},
+	}
+
+	extra := types.DiagnosticExtra{
+		Code: "foo",
+	}
+	types.SetDiagnosticExtra(diag, extra)
+
+	// The parent wrapped is lost
+	isExtra, ok := diag.Extra.(types.DiagnosticExtra)
+	require.True(t, ok)
+	require.Equal(t, "foo", isExtra.Code)
+	wrapped, ok := isExtra.UnwrapDiagnosticExtra().(wrappedDiagnostic)
+	require.True(t, ok)
+	require.Equal(t, wrapped.name, "child")
+}
+
 func TestDiagnosticsJSON(t *testing.T) {
 	diags := types.Diagnostics{
 		{
@@ -64,3 +102,14 @@ func TestDiagnosticsJSON(t *testing.T) {
 
 	require.Equal(t, diags, newDiags)
 }
+
+type wrappedDiagnostic struct {
+	name    string
+	wrapped any
+}
+
+var _ hcl.DiagnosticExtraUnwrapper = wrappedDiagnostic{}
+
+func (e wrappedDiagnostic) UnwrapDiagnosticExtra() interface{} {
+	return e.wrapped
+}