Ensure CommandExecutor panics if passed an unrecognized command.

enginetest/executor.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 
 	"github.com/dogmatiq/dogma"
+	"github.com/dogmatiq/dogma/fixtures"
 	"github.com/dogmatiq/testkit/enginetest/internal/app"
 )
 
@@ -32,5 +33,20 @@ func testCommandExecutor(
 
 			x.ExecuteCommand(ctx, &app.IntegrationCommand{})
 		})
+
+		t.Run("it panics if passed an unrecognized command", func(t *testing.T) {
+			t.Parallel()
+
+			defer func() {
+				actual := fmt.Sprint(recover())
+				expect := "MessageC" // the type name should appear in the message
+
+				if !strings.Contains(actual, expect) {
+					t.Fatalf("got: %q, want: panic containing %q", actual, expect)
+				}
+			}()
+
+			x.ExecuteCommand(ctx, fixtures.MessageC1)
+		})
 	})
 }