Prevent numbers in module/pipe names

[nikita-fuchs]

Bug Report or Feature Request (mark with an x)

- [X] bug report -> please search issues before submitting
- [ ] feature request

Command (mark with an x)

- [ ] new
- [ ] build
- [ ] serve
- [ ] test
- [ ] e2e
- [X] generate
- [ ] add
- [ ] update
- [ ] lint
- [ ] xi18n
- [ ] run
- [ ] config
- [ ] help
- [ ] version
- [ ] doc

Versions

Angular CLI: 6.2.1
Node: 8.11.2
OS: darwin x64
Angular: 6.1.7
... animations, common, compiler, compiler-cli, core, forms
... http, language-service, platform-browser
... platform-browser-dynamic, platform-server, router

Package Version

@angular-devkit/architect 0.8.1
@angular-devkit/build-angular 0.8.1
@angular-devkit/build-webpack 0.8.1
@angular-devkit/core 0.8.1
@angular-devkit/schematics 0.8.1
@angular/cdk 6.4.7
@angular/cli 6.2.1
@angular/material 6.4.7
@schematics/angular 0.8.1
@schematics/update 0.8.1
rxjs 6.3.2
typescript 2.9.2
webpack 4.19.0

Repro steps

ng generate pipe 18decimals

The log given by the failure

Everything performs smoothly. The pipe is created, but referencing modules with numbers in name creates problems, like here, referencing names with numbers.

import { 18decimalsPipe } from './18decimals.pipe';

describe('18decimalsPipe', () => {
  it('create an instance', () => {
    const pipe = new 18decimalsPipe();
    expect(pipe).toBeTruthy();
  });
});

Desired functionality

The cli should disallow names with numbers to prevent issues.