Add specs for hex colors with alpha components

This adds specs for both the deprecation behavior and the eventual
post-deprecation behavior.

See sass/sass#2179

spec/css/color/alpha_hex/deprecation/error

@@ -0,0 +1,39 @@
+DEPRECATION WARNING on line 6, column 15 of /sass/spec/css/color/alpha_hex/deprecation/input.scss: 
+The value "#AbCd" is currently parsed as a string, but it will be parsed as a
+color in a release on or after 19 September 2018.
+
+To continue parsing it as a string, use "unquote('#AbCd')".
+To parse it as a color, use "rgba(170, 187, 204, 0.8666666667)".
+
+  four-digit: #AbCd;
+              ^^^^^
+
+DEPRECATION WARNING on line 7, column 16 of /sass/spec/css/color/alpha_hex/deprecation/input.scss: 
+The value "#aBcDeFaB" is currently parsed as a string, but it will be parsed as a
+color in a release on or after 19 September 2018.
+
+To continue parsing it as a string, use "unquote('#aBcDeFaB')".
+To parse it as a color, use "rgba(171, 205, 239, 0.6705882353)".
+
+  eight-digit: #aBcDeFaB;
+               ^^^^^^^^^
+
+DEPRECATION WARNING on line 8, column 28 of /sass/spec/css/color/alpha_hex/deprecation/input.scss: 
+The value "#abcd" is currently parsed as a string, but it will be parsed as a
+color in a release on or after 19 September 2018.
+
+To continue parsing it as a string, use "unquote('#abcd')".
+To parse it as a color, use "rgba(170, 187, 204, 0.8666666667)".
+
+  four-digit-type: type-of(#abcd);
+                           ^^^^^
+
+DEPRECATION WARNING on line 9, column 29 of /sass/spec/css/color/alpha_hex/deprecation/input.scss: 
+The value "#ABCDEFAB" is currently parsed as a string, but it will be parsed as a
+color in a release on or after 19 September 2018.
+
+To continue parsing it as a string, use "unquote('#ABCDEFAB')".
+To parse it as a color, use "rgba(171, 205, 239, 0.6705882353)".
+
+  eight-digit-type: type-of(#ABCDEFAB);
+                            ^^^^^^^^^

spec/css/color/alpha_hex/deprecation/error-libsass

@@ -0,0 +1,7 @@
+DEPRECATION WARNING on line 8, column 33 of /sass/spec/css/color/alpha_hex/deprecation/input.scss:
+The value "#abcd" is currently parsed as a string, but it will be parsed as a color in
+future versions of Sass. Use "unquote('#abcd')" to continue parsing it as a string.
+
+DEPRECATION WARNING on line 9, column 38 of /sass/spec/css/color/alpha_hex/deprecation/input.scss:
+The value "#ABCDEFAB" is currently parsed as a string, but it will be parsed as a color in
+future versions of Sass. Use "unquote('#ABCDEFAB')" to continue parsing it as a string.

spec/css/color/alpha_hex/deprecation/expected_output.css

@@ -0,0 +1,6 @@
+a {
+  four-digit: #AbCd;
+  eight-digit: #aBcDeFaB;
+  four-digit-type: string;
+  eight-digit-type: string;
+}

spec/css/color/alpha_hex/deprecation/input.scss

@@ -0,0 +1,10 @@
+// This spec tests the intermediate behavior of Sass implementations that have
+// deprecated parsing tokens as unquoted strings when they're ambiguous between
+// IDs or hex RGBA colors. These implementations should continue to parse those
+// tokens as strings, but should emit a warning.
+a {
+  four-digit: #AbCd;
+  eight-digit: #aBcDeFaB;
+  four-digit-type: type-of(#abcd);
+  eight-digit-type: type-of(#ABCDEFAB);
+}

spec/css/color/alpha_hex/deprecation/options.yml

@@ -0,0 +1,3 @@
+---
+:ignore_for:
+- ruby-sass

spec/css/color/alpha_hex/initial_digit/expected_output-ruby-sass.css

@@ -0,0 +1,12 @@
+a {
+  four-digit: #0123;
+  eight-digit: #98765432;
+  four-digit-red: 0;
+  four-digit-green: 17;
+  four-digit-blue: 34;
+  four-digit-alpha: 0.2;
+  eight-digit-red: 152;
+  eight-digit-green: 118;
+  eight-digit-blue: 84;
+  eight-digit-alpha: 0.19608;
+}

spec/css/color/alpha_hex/initial_digit/expected_output.css

@@ -0,0 +1,12 @@
+a {
+  four-digit: #0123;
+  eight-digit: #98765432;
+  four-digit-red: 0;
+  four-digit-green: 17;
+  four-digit-blue: 34;
+  four-digit-alpha: 0.2;
+  eight-digit-red: 152;
+  eight-digit-green: 118;
+  eight-digit-blue: 84;
+  eight-digit-alpha: 0.1960784314;
+}

spec/css/color/alpha_hex/initial_digit/input.scss

@@ -0,0 +1,15 @@
+a {
+  four-digit: #0123;
+  eight-digit: #98765432;
+
+  // Verify that the color channels are set correctly.
+  four-digit-red: red(#0123);
+  four-digit-green: green(#0123);
+  four-digit-blue: blue(#0123);
+  four-digit-alpha: alpha(#0123);
+
+  eight-digit-red: red(#98765432);
+  eight-digit-green: green(#98765432);
+  eight-digit-blue: blue(#98765432);
+  eight-digit-alpha: alpha(#98765432);
+}

spec/css/color/alpha_hex/initial_digit/options.yml

@@ -0,0 +1,4 @@
+---
+:start_version: '3.6'
+:todo:
+- libsass

spec/css/color/alpha_hex/initial_letter/expected_output-ruby-sass.css

@@ -0,0 +1,12 @@
+a {
+  four-digit: #AbCd;
+  eight-digit: #aBcDeF12;
+  four-digit-red: 170;
+  four-digit-green: 187;
+  four-digit-blue: 204;
+  four-digit-alpha: 0.86667;
+  eight-digit-red: 171;
+  eight-digit-green: 205;
+  eight-digit-blue: 239;
+  eight-digit-alpha: 0.07059;
+}

spec/css/color/alpha_hex/initial_letter/expected_output.css

@@ -0,0 +1,12 @@
+a {
+  four-digit: #AbCd;
+  eight-digit: #aBcDeF12;
+  four-digit-red: 170;
+  four-digit-green: 187;
+  four-digit-blue: 204;
+  four-digit-alpha: 0.8666666666;
+  eight-digit-red: 171;
+  eight-digit-green: 205;
+  eight-digit-blue: 239;
+  eight-digit-alpha: 0.0705882353;
+}

spec/css/color/alpha_hex/initial_letter/input.scss

@@ -0,0 +1,15 @@
+a {
+  four-digit: #AbCd;
+  eight-digit: #aBcDeF12;
+
+  // Verify that the color channels are set correctly.
+  four-digit-red: red(#abcd);
+  four-digit-green: green(#abcd);
+  four-digit-blue: blue(#abcd);
+  four-digit-alpha: alpha(#abcd);
+
+  eight-digit-red: red(#ABCDEF12);
+  eight-digit-green: green(#ABCDEF12);
+  eight-digit-blue: blue(#ABCDEF12);
+  eight-digit-alpha: alpha(#ABCDEF12);
+}

spec/css/color/alpha_hex/initial_letter/options.yml

@@ -0,0 +1,5 @@
+---
+:start_version: '3.6'
+:todo:
+- dart-sass
+- libsass

spec/css/id_values/expected_output.css

@@ -0,0 +1,10 @@
+a {
+  two-letters: #ab;
+  five-letters: #abcde;
+  seven-letters: #abcdefa;
+  nine-letters: #abcdefabc;
+  three-letters-not-hex: #axc;
+  four-letters-not-hex: #axcd;
+  six-letters-not-hex: #abcxde;
+  eight-letters-not-hex: #abcxdefa;
+}

spec/css/id_values/input.scss

@@ -0,0 +1,16 @@
+// The CSS nav-up property and its siblings allow ID tokens in their values, so
+// Sass parses any tokens that start with a "#" followed by an identifier as an
+// ID if it can't be parsed as a color.
+a {
+  // These IDs are the wrong number of letters to be a hex color.
+  two-letters: #ab;
+  five-letters: #abcde;
+  seven-letters: #abcdefa;
+  nine-letters: #abcdefabc;
+
+  // These IDs contain letters outside the hexadecimal gamut.
+  three-letters-not-hex: #axc;
+  four-letters-not-hex: #axcd;
+  six-letters-not-hex: #abcxde;
+  eight-letters-not-hex: #abcxdefa;
+}