Service Injection

test.component.ts

import { Component, OnInit } from '@angular/core';
import { TestService } from 'src/app/services/test.service';

@Component({
  selector: 'app-test',
  templateUrl: './test.component.html',
  styleUrls: ['./test.component.scss'],
})
export class TestComponent implements OnInit {
  text: string;

  constructor(
    private testService: TestService, // the DI makes sure you get an instance
  ) { }

  ngOnInit() {
    this.text = this.testService.getTest();
  }
}