This page documents the 0.4 release candidates of @nexusdi/core. The newest on npm is 0.4.0-rc.1. The documentation for 0.3.2, the current release, is at nexus.js.org. Try the release candidate.

NEXUS_OVERRIDE_UNUSED

createTestingContainer(root).create() reports NEXUS_OVERRIDE_UNUSED when an override(TOKEN, ...) call names a token that no provider in the module graph binds, or an overrideModule(module, stub) call names a module that the graph never imports. The testing container runs the full compiler, so an override that replaces nothing fails the test at create and the test never runs against a graph it does not describe. create() rejects with NEXUS_BLUEPRINT_INVALID holding the error, and no call raises NEXUS_OVERRIDE_UNUSED bare. The check runs at create() only. An overrideModule(module, stub, { lazy: true }) call is exempt, because a later ship.load() may bring the module in.

Reproduce NEXUS_OVERRIDE_UNUSED

The test overrides NAV_CHARTS, and the module under test provides only REACTOR. @nexusdi/testing writes this message itself, so it carries its full text and fix line with no text pack, and errors({ text }) leaves it as written.

import { Token, defineModule, isNexusError, provide } from '@nexusdi/core';
import { createTestingContainer } from '@nexusdi/testing';
 
interface IReactorCore {
  readonly output: number;
}
interface INavCharts {
  plot(to: string): string;
}
const REACTOR = new Token<IReactorCore>('ReactorCore');
const NAV_CHARTS = new Token<INavCharts>('NavCharts');
 
const fakeCharts: INavCharts = { plot: (to) => `loopback course to ${to}` };
 
class FusionReactor implements IReactorCore {
  readonly output = 1.21;
}
const Engineering = defineModule({
  name: 'Engineering',
  providers: [provide(REACTOR, { useClass: FusionReactor })],
  exports: [REACTOR],
});
 
// Engineering provides no NAV_CHARTS, so the override replaces nothing.
const error = await createTestingContainer(Engineering)
  .override(NAV_CHARTS, { useValue: fakeCharts })
  .create()
  .catch((caught: unknown) => caught);
const inner = isNexusError(error, 'NEXUS_BLUEPRINT_INVALID')
  ? error.errors[0]
  : undefined;
const lines = inner?.message.split('\n'); // -> ['[NEXUS_OVERRIDE_UNUSED] override(NavCharts) matched no provider in the module graph.', '  Fix: remove the override, or import the module that provides NavCharts.']
console.log(lines?.join('\n'));

Try it: run npm install @nexusdi/core@next and npm install -D @nexusdi/testing@next, save the region as override.ts and run npx tsx override.ts. It prints the two-line message with its Fix: line: [NEXUS_OVERRIDE_UNUSED] override(NavCharts) matched no provider in the module graph. and Fix: remove the override, or import the module that provides NavCharts. Then add provide(NAV_CHARTS, { useValue: fakeCharts }) to the providers of Engineering and run it again. The override replaces that provider, the container builds, and the region prints undefined because there is no error to read.

Fix NEXUS_OVERRIDE_UNUSED

NEXUS_OVERRIDE_UNUSED goes away when the root passed to createTestingContainer imports the module that provides the overridden token, or when the test drops the override. An override for a module that a later ship.load() adds belongs on overrideModule(module, stub, { lazy: true }).

import { Token, defineModule, provide } from '@nexusdi/core';
import { createTestingContainer } from '@nexusdi/testing';
 
interface INavCharts {
  plot(to: string): string;
}
const NAV_CHARTS = new Token<INavCharts>('NavCharts');
 
const Tactical = defineModule({
  name: 'Tactical',
  providers: [
    provide(NAV_CHARTS, {
      useFactory: async (): Promise<INavCharts> => ({
        plot: (to) => `course to ${to}`,
      }),
    }),
  ],
  exports: [NAV_CHARTS],
});
const Meridian = defineModule({ name: 'Meridian', imports: [Tactical] });
 
const fakeCharts: INavCharts = { plot: (to) => `loopback course to ${to}` };
 
await using ship = await createTestingContainer(Meridian)
  .override(NAV_CHARTS, { useValue: fakeCharts })
  .create();
const course = ship.get(NAV_CHARTS).plot('Kepler-442b'); // -> 'loopback course to Kepler-442b'
console.log(course);

Try it: save the region as fixed.ts and run npx tsx fixed.ts. It prints loopback course to Kepler-442b. Change imports: [Tactical] in Meridian to imports: [] and run it again. npx tsc accepts the file, and npx tsx fixed.ts throws an uncaught BlueprintError and prints a stack trace headed BlueprintError: [NEXUS_BLUEPRINT_INVALID] 1 error. Put the import back and the program prints loopback course to Kepler-442b again.

Fields of OverrideError

• code: 'NEXUS_OVERRIDE_UNUSED' or 'NEXUS_OVERRIDE_EXPORTS'.
• token: for NEXUS_OVERRIDE_UNUSED, the name of the unused override: the token’s name, such as 'NavCharts', or the module’s name for an unused overrideModule(), such as 'Comms'. null for NEXUS_OVERRIDE_EXPORTS.
• module: null for NEXUS_OVERRIDE_UNUSED.
• missing: an empty array for NEXUS_OVERRIDE_UNUSED.