test-config.helper.ts

import { TestBed } from '@angular/core/testing'

type CompilerOptions = Partial<{
    providers: any[]
    useJit: boolean
    preserveWhitespaces: boolean
}>
export type ConfigureFn = (testBed: typeof TestBed) => void

export const configureTests = (configure: ConfigureFn, compilerOptions: CompilerOptions = {}) => {
    const compilerConfig: CompilerOptions = {
        preserveWhitespaces: false,
        ...compilerOptions,
    }

    const configuredTestBed = TestBed.configureCompiler(compilerConfig)

    configure(configuredTestBed)

    return configuredTestBed.compileComponents().then(() => configuredTestBed)
}