Reorganize tests into a real spec suite

spec/unsupported_lexers/peg/test_basic.txt

@@ -0,0 +1,17 @@
+---input---
+rule<-("terminal"/nonterminal/[cls])*
+
+---tokens---
+'rule'        Name.Class
+'<-'          Operator
+'('           Punctuation
+'"terminal"'  Literal.String.Double
+'/'           Operator
+'nonterminal' Name.Class
+'/'           Operator
+'['           Punctuation
+'cls'         Literal.String
+']'           Punctuation
+')'           Punctuation
+'*'           Operator
+'\n'          Text.Whitespace

spec/unsupported_lexers/peg/test_modified_strings.txt

@@ -0,0 +1,21 @@
+# see for example:
+# - http://textx.github.io/Arpeggio/
+# - https://nim-lang.org/docs/pegs.html
+# - https://github.com/erikrose/parsimonious
+# can't handle parsimonious-style regex while ~ is a cut operator
+
+---input---
+~"regex" i"insensitive" "multimod"ilx ("not modified")
+
+---tokens---
+'~'           Operator
+'"regex"'     Literal.String.Double
+' '           Text
+'i"insensitive"' Literal.String.Double
+' '           Text
+'"multimod"ilx' Literal.String.Double
+' '           Text
+'('           Punctuation
+'"not modified"' Literal.String.Double
+')'           Punctuation
+'\n'          Text.Whitespace

spec/unsupported_lexers/peg/test_operators.txt

@@ -0,0 +1,29 @@
+# see for example:
+# - https://github.com/gvanrossum/pegen
+# - https://nim-lang.org/docs/pegs.html
+
+---input---
+rule = 'a' | 'b'
+rule: 'a' ~ 'b'
+
+---tokens---
+'rule'        Name.Class
+' '           Text
+'='           Operator
+' '           Text
+"'a'"         Literal.String.Single
+' '           Text
+'|'           Operator
+' '           Text
+"'b'"         Literal.String.Single
+'\n'          Text.Whitespace
+
+'rule'        Name.Class
+':'           Operator
+' '           Text
+"'a'"         Literal.String.Single
+' '           Text
+'~'           Operator
+' '           Text
+"'b'"         Literal.String.Single
+'\n'          Text.Whitespace