Tighten NPC interaction validation and consistency

internal/modules/dnd/shared/diagnostics/diagnostics_test.go

@@ -2,9 +2,12 @@ package diagnostics
 
 import (
 	"fmt"
+	"reflect"
 	"strings"
 	"testing"
 	"unicode/utf8"
+
+	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
 )
 
 func TestAggregateEnforcesByteBudgetAndReportsOmissions(t *testing.T) {
@@ -26,3 +29,25 @@ func TestAggregateEnforcesByteBudgetAndReportsOmissions(t *testing.T) {
 		t.Fatalf("Aggregate() = %q, want %q", message, wantOmitted)
 	}
 }
+
+func TestLimitWarningsBoundsOutputAndReportsOmissions(t *testing.T) {
+	warnings := make([]contracts.Warning, MaxWarnings+3)
+	for index := range warnings {
+		warnings[index] = contracts.Warning{ReasonCode: fmt.Sprintf("warning-%d", index)}
+	}
+	before := append([]contracts.Warning(nil), warnings...)
+
+	got := LimitWarnings(warnings, "records", "warnings_omitted")
+	if len(got) != MaxWarnings {
+		t.Fatalf("LimitWarnings() count = %d, want %d", len(got), MaxWarnings)
+	}
+	summary := got[len(got)-1]
+	wantOmitted := len(warnings) - (MaxWarnings - 1)
+	if summary.Scope != "records" || summary.ReasonCode != "warnings_omitted" ||
+		summary.Message != fmt.Sprintf("%d additional warning(s) omitted", wantOmitted) {
+		t.Fatalf("summary = %#v", summary)
+	}
+	if !reflect.DeepEqual(warnings, before) {
+		t.Fatal("LimitWarnings() mutated its input")
+	}
+}