Add additional regression tests for implicit configuration

spec/directives/import/configuration/import_twice.hrx

@@ -0,0 +1,138 @@
+<===> no_change/input.scss
+$a: configured;
+@import "other";
+@import "other";
+
+<===> no_change/_other.scss
+$a: original !default;
+b {c: $a}
+
+<===> no_change/_other.import.scss
+@forward "other";
+
+<===> no_change/output.css
+b {
+  c: configured;
+}
+
+b {
+  c: configured;
+}
+
+<===> no_change/warning
+DEPRECATION WARNING [import]: Sass @import rules are deprecated and will be removed in Dart Sass 3.0.0.
+
+More info and automated migrator: https://sass-lang.com/d/import
+
+  ,
+2 | @import "other";
+  |         ^^^^^^^
+  '
+    input.scss 2:9  root stylesheet
+
+DEPRECATION WARNING [import]: Sass @import rules are deprecated and will be removed in Dart Sass 3.0.0.
+
+More info and automated migrator: https://sass-lang.com/d/import
+
+  ,
+3 | @import "other";
+  |         ^^^^^^^
+  '
+    input.scss 3:9  root stylesheet
+
+<===>
+================================================================================
+<===> with_change/input.scss
+$a: configured;
+@import "other";
+$a: changed; // This should be ignored
+@import "other";
+
+<===> with_change/_other.scss
+$a: original !default;
+b {c: $a}
+
+<===> with_change/_other.import.scss
+@forward "other";
+
+<===> with_change/output.css
+b {
+  c: configured;
+}
+
+b {
+  c: configured;
+}
+
+<===> with_change/warning
+DEPRECATION WARNING [import]: Sass @import rules are deprecated and will be removed in Dart Sass 3.0.0.
+
+More info and automated migrator: https://sass-lang.com/d/import
+
+  ,
+2 | @import "other";
+  |         ^^^^^^^
+  '
+    input.scss 2:9  root stylesheet
+
+DEPRECATION WARNING [import]: Sass @import rules are deprecated and will be removed in Dart Sass 3.0.0.
+
+More info and automated migrator: https://sass-lang.com/d/import
+
+  ,
+4 | @import "other";
+  |         ^^^^^^^
+  '
+    input.scss 4:9  root stylesheet
+
+<===>
+================================================================================
+<===> still_changes_in_same_file/input.scss
+@import "other";
+$a: changed;
+@import "other";
+
+d {
+  e: $a;
+}
+
+<===> still_changes_in_same_file/_other.scss
+$a: original !default;
+b {c: $a}
+
+<===> still_changes_in_same_file/_other.import.scss
+@forward "other";
+
+<===> still_changes_in_same_file/output.css
+b {
+  c: original;
+}
+
+b {
+  c: original;
+}
+
+d {
+  e: changed;
+}
+
+<===> still_changes_in_same_file/warning
+DEPRECATION WARNING [import]: Sass @import rules are deprecated and will be removed in Dart Sass 3.0.0.
+
+More info and automated migrator: https://sass-lang.com/d/import
+
+  ,
+1 | @import "other";
+  |         ^^^^^^^
+  '
+    input.scss 1:9  root stylesheet
+
+DEPRECATION WARNING [import]: Sass @import rules are deprecated and will be removed in Dart Sass 3.0.0.
+
+More info and automated migrator: https://sass-lang.com/d/import
+
+  ,
+3 | @import "other";
+  |         ^^^^^^^
+  '
+    input.scss 3:9  root stylesheet

spec/directives/import/configuration/indirect.hrx

@@ -0,0 +1,75 @@
+<===> through_import/input.scss
+$a: configured;
+@import "midstream";
+
+<===> through_import/_midstream.scss
+@import "upstream";
+
+<===> through_import/_upstream.scss
+$a: original !default;
+b {c: $a}
+
+<===> through_import/_upstream.import.scss
+@forward "upstream";
+
+<===> through_import/output.css
+b {
+  c: configured;
+}
+
+<===> through_import/warning
+DEPRECATION WARNING [import]: Sass @import rules are deprecated and will be removed in Dart Sass 3.0.0.
+
+More info and automated migrator: https://sass-lang.com/d/import
+
+  ,
+2 | @import "midstream";
+  |         ^^^^^^^^^^^
+  '
+    input.scss 2:9  root stylesheet
+
+DEPRECATION WARNING [import]: Sass @import rules are deprecated and will be removed in Dart Sass 3.0.0.
+
+More info and automated migrator: https://sass-lang.com/d/import
+
+  ,
+1 | @import "upstream";
+  |         ^^^^^^^^^^
+  '
+    _midstream.scss 1:9  @import
+    input.scss 2:9       root stylesheet
+
+<===>
+================================================================================
+<===> through_forward/input.scss
+$a: configured;
+@import "midstream";
+
+<===> through_forward/_midstream.scss
+@forward "upstream";
+
+<===> through_forward/_midstream.import.scss
+@forward "midstream";
+
+<===> through_forward/_upstream.scss
+$a: original !default;
+b {c: $a}
+
+<===> through_forward/_upstream.import.scss
+@forward "upstream";
+
+<===> through_forward/output.css
+b {
+  c: configured;
+}
+
+<===> through_forward/warning
+DEPRECATION WARNING [import]: Sass @import rules are deprecated and will be removed in Dart Sass 3.0.0.
+
+More info and automated migrator: https://sass-lang.com/d/import
+
+  ,
+2 | @import "midstream";
+  |         ^^^^^^^^^^^
+  '
+    input.scss 2:9  root stylesheet

spec/directives/import/configuration/midstream_definition.hrx

@@ -0,0 +1,56 @@
+<===> with_config/input.scss
+$a: configured;
+@import "midstream";
+
+<===> with_config/_midstream.scss
+$a: midstream;
+@forward "upstream";
+
+<===> with_config/_upstream.scss
+$a: original !default;
+b {c: $a}
+
+<===> with_config/output.css
+b {
+  c: configured;
+}
+
+<===> with_config/warning
+DEPRECATION WARNING [import]: Sass @import rules are deprecated and will be removed in Dart Sass 3.0.0.
+
+More info and automated migrator: https://sass-lang.com/d/import
+
+  ,
+2 | @import "midstream";
+  |         ^^^^^^^^^^^
+  '
+    input.scss 2:9  root stylesheet
+
+<===>
+================================================================================
+<===> no_config/input.scss
+@import "midstream";
+
+<===> no_config/_midstream.scss
+$a: midstream;
+@forward "upstream";
+
+<===> no_config/_upstream.scss
+$a: original !default;
+b {c: $a}
+
+<===> no_config/output.css
+b {
+  c: original;
+}
+
+<===> no_config/warning
+DEPRECATION WARNING [import]: Sass @import rules are deprecated and will be removed in Dart Sass 3.0.0.
+
+More info and automated migrator: https://sass-lang.com/d/import
+
+  ,
+1 | @import "midstream";
+  |         ^^^^^^^^^^^
+  '
+    input.scss 1:9  root stylesheet

spec/directives/import/configuration/nested.hrx

@@ -0,0 +1,28 @@
+<===> input.scss
+a {
+  $a: configured;
+  @import "midstream";
+}
+
+<===> _midstream.scss
+@forward "upstream";
+
+<===> _upstream.scss
+$a: original !default;
+b {c: $a}
+
+<===> output.css
+a b {
+  c: configured;
+}
+
+<===> warning
+DEPRECATION WARNING [import]: Sass @import rules are deprecated and will be removed in Dart Sass 3.0.0.
+
+More info and automated migrator: https://sass-lang.com/d/import
+
+  ,
+3 |   @import "midstream";
+  |           ^^^^^^^^^^^
+  '
+    input.scss 3:11  root stylesheet

spec/directives/import/configuration/prefixed_as.hrx

@@ -0,0 +1,26 @@
+<===> input.scss
+$d-a: configured;
+@import "midstream";
+
+<===> _midstream.scss
+@forward "upstream" as d-*;
+
+<===> _upstream.scss
+$a: original !default;
+b {c: $a}
+
+<===> output.css
+b {
+  c: configured;
+}
+
+<===> warning
+DEPRECATION WARNING [import]: Sass @import rules are deprecated and will be removed in Dart Sass 3.0.0.
+
+More info and automated migrator: https://sass-lang.com/d/import
+
+  ,
+2 | @import "midstream";
+  |         ^^^^^^^^^^^
+  '
+    input.scss 2:9  root stylesheet

spec/directives/import/configuration/same_file.hrx

@@ -0,0 +1,26 @@
+<===> input.scss
+$a: configured;
+@import "midstream";
+
+<===> _midstream.scss
+@forward "upstream";
+
+<===> _upstream.scss
+$a: original !default;
+b {c: $a}
+
+<===> output.css
+b {
+  c: configured;
+}
+
+<===> warning
+DEPRECATION WARNING [import]: Sass @import rules are deprecated and will be removed in Dart Sass 3.0.0.
+
+More info and automated migrator: https://sass-lang.com/d/import
+
+  ,
+2 | @import "midstream";
+  |         ^^^^^^^^^^^
+  '
+    input.scss 2:9  root stylesheet