anchor.diff:        await tick;
         await d.file("other.scss", r"x {y: $var}").create();
   
  -      sass = await runSass([
  -        "--no-source-map",
  -        "--update",
  -        "test1.scss:out1.css",
  -        "test2.scss:out2.css"
  -      ]);
  +      sass = await update(["test1.scss:out1.css", "test2.scss:out2.css"]);
         expect(sass.stdout, emits('Compiled test1.scss to out1.css.'));
         expect(sass.stdout, emits('Compiled test2.scss to out2.css.'));
         await sass.shouldExit(0);
  
positive.code:       await d.file("other.scss", "a {b: c}").create();
        await d.file("test.scss", "@import 'other'").create();
  
        var sass =
            await runSass(["--no-source-map", "--update", "test.scss:out.css"]);
        expect(sass.stdout, emits('Compiled test.scss to out.css.'));
        await sass.shouldExit(0);
  
        await tick;
        await d.file("other.scss", "x {y: z}").create();
  
        sass =
            await runSass(["--no-source-map", "--update", "test.scss:out.css"]);
        expect(sass.stdout, emits('Compiled test.scss to out.css.'));
        await sass.shouldExit(0);
  
  
negative.code:       await tick;
        await d.file("test.scss", "a {b: c}").create();
  
        var sass = await update(["test.scss:out.css"]);
        expect(sass.stdout, emits('Compiled test.scss to out.css.'));
        await sass.shouldExit(0);
  
  