instanceof-check

This rule highlights whenever an instanceof expression is used in tab code against a type that is imported from a bundle or the modules library. Such checks might fail at runtime as described here

The rule can be configured with an array of regex strings to match against import sources that might cause runtime instanceof checks to fail. For example:

// By default, the rule matches against bundles and modules-lib

const config = {
  '@sourceacademy/instanceof-check': [
    'error', [
      '@sourceacademy/bundle-.+',
      '@sourceacademy/modules-lib(?:/.+)?',
    ]
  ]
};

✅ Examples of correct code for this rule

The rule will not highlight when the instanceof check is being performed against an imported class is being imported from a bundle or modules-lib.

foo/index.tsx

import { defineTab, getModuleState } from '@sourceacademy/modules-lib/tabs/utils';
import { ClassX } from 'some_package';

export default defineTab({
  toSpawn(context) {
    return getModuleState(context, 'foo') instanceof ClassX;
  },
  body() {
    return <FooTab />;
  },
  label: 'FooTab',
  iconName: 'shapes'
});

❌ Examples of incorrect code for this rule

The rule will highlight when the instanceof check is being performed against an imported class is being imported from a bundle or modules-lib.

foo/index.tsx

import { ClassX } from '@sourceacademy/bundle-foo';
import { defineTab, getModuleState } from '@sourceacademy/modules-lib/tabs/utils';

export default defineTab({
  toSpawn(context) {
    // By comparing to a class from a bundle via a tab, this check
    // might fail at runtime unintentionally
    return getModuleState(context, 'foo') instanceof ClassX;
  },
  body() {
    return <FooTab />;
  },
  label: 'FooTab',
  iconName: 'shapes'
});