<===> optional_and_mandatory/README.md
If an optional and a mandatory version of the same extension both exist, the
mandatory version should still fail.

<===>
================================================================================
<===> optional_and_mandatory/same_file/input.scss
@use "other";

in-input {
  @extend %-in-other !optional;
  @extend %-in-other;
}

<===> optional_and_mandatory/same_file/_other.scss
%-in-other {x: y}

<===> optional_and_mandatory/same_file/error
Error: The target selector was not found.
Use "@extend %-in-other !optional" to avoid this error.
  ,
5 |   @extend %-in-other;
  |   ^^^^^^^^^^^^^^^^^^
  '
  input.scss 5:3  root stylesheet

<===>
================================================================================
<===> optional_and_mandatory/different_files/input.scss
@use "optional";
@use "mandatory";

<===> optional_and_mandatory/different_files/_optional.scss
@use "shared";

downstream {@extend %-in-other !optional};

<===> optional_and_mandatory/different_files/_mandatory.scss
@use "shared";

downstream {@extend %-in-other};

<===> optional_and_mandatory/different_files/_shared.scss
%-in-other {x: y}

<===> optional_and_mandatory/different_files/error
Error: The target selector was not found.
Use "@extend %-in-other !optional" to avoid this error.
  ,
3 | downstream {@extend %-in-other};
  |             ^^^^^^^^^^^^^^^^^^
  '
  _mandatory.scss 3:13  root stylesheet

<===>
================================================================================
<===> scope/README.md
All tests in this directory use mandatory extends to test extensions that don't
have matches. Each test should have a counterpart in the non-error extend tests
that tests the same thing but with `!optional` to verify that it doesn't produce
an error message.

<===>
================================================================================
<===> scope/sibling/input.scss
@use "left";
@use "right";

<===> scope/sibling/_left.scss
left-extendee {in: left}
left-extender {@extend right-extendee}

<===> scope/sibling/_right.scss
right-extendee {in: right}

<===> scope/sibling/error
Error: The target selector was not found.
Use "@extend right-extendee !optional" to avoid this error.
  ,
2 | left-extender {@extend right-extendee}
  |                ^^^^^^^^^^^^^^^^^^^^^^
  '
  _left.scss 2:16  root stylesheet

<===>
================================================================================
<===> scope/downstream/input.scss
@use "other";

in-input {x: y}

<===> scope/downstream/_other.scss
in-other {@extend in-input}

<===> scope/downstream/error
Error: The target selector was not found.
Use "@extend in-input !optional" to avoid this error.
  ,
1 | in-other {@extend in-input}
  |           ^^^^^^^^^^^^^^^^
  '
  _other.scss 1:11  root stylesheet

<===>
================================================================================
<===> scope/private/input.scss
@use "other";

in-input {@extend %-in-other}

<===> scope/private/_other.scss
%-in-other {x: y}

in-other {@extend %-in-other}

<===> scope/private/error
Error: The target selector was not found.
Use "@extend %-in-other !optional" to avoid this error.
  ,
3 | in-input {@extend %-in-other}
  |           ^^^^^^^^^^^^^^^^^^
  '
  input.scss 3:11  root stylesheet

<===>
================================================================================
<===> scope/diamond/input.scss
// Even though left-extendee and right-extendee both end up in the style rule
// defined in _shared.scss, they aren't extended by the other file because those
// files don't use one another.
@use "left";
@use "right";

<===> scope/diamond/_left.scss
@use "shared";

left-extendee {@extend in-shared}
left-extender {@extend right-extendee}

<===> scope/diamond/_right.scss
@use "shared";

right-extendee {@extend in-shared}

<===> scope/diamond/_shared.scss
in-shared {x: y}

<===> scope/diamond/error
Error: The target selector was not found.
Use "@extend right-extendee !optional" to avoid this error.
  ,
4 | left-extender {@extend right-extendee}
  |                ^^^^^^^^^^^^^^^^^^^^^^
  '
  _left.scss 4:16  root stylesheet