sgf-parsing: Add individual tests of escaping/whitespace behaviour

previous case "escaped property value" crams too much into one test
case.  Split it up into multiple ones.

The reimplemented case is mostly as it was when the exercise was
originally implemented in
exercism/exercism@7a5075b

Note that the original case also got it wrong in that newlines should
remain newlines; this is corrected in the new case.

exercism/problem-specifications#1889

exercises/practice/sgf-parsing/.meta/examples/success-standard/src/Sgf.hs

@@ -5,7 +5,7 @@ module Sgf (
 
 import           Control.Applicative (many)
 import           Data.Attoparsec.Text (Parser, anyChar, char, many1, parseOnly, satisfy)
-import           Data.Char (isUpper, isSpace)
+import           Data.Char (isUpper)
 import           Data.Map (Map)
 import qualified Data.Map as Map
 import           Data.Tree (Tree(..))
@@ -51,7 +51,7 @@ val = char '[' *> worker [] False
             ']'  | not bs    -> return . T.pack . reverse $ acc
             '\\' | not bs    -> worker acc True
             '\n' | bs        -> worker acc False -- remove soft newline
-            _    | isSpace c -> worker (' ' : acc) False
+            '\t'             -> worker (' ' : acc) False
             _                -> worker (c : acc) False
 
 -- | Create an 'SgfTree' from a list of nodes and subtrees.

exercises/practice/sgf-parsing/test/Tests.hs

@@ -44,7 +44,27 @@ specs = describe "parseSgf" $ for_ cases test
                                                                                   , Node [("C", ["D"])] [] ] )
             -- multiple property values
             , ("(;A[b][c][d])"                      , Just  $ Node [("A", ["b", "c", "d" ])] []              )
-            -- escaped property value
-            , ("(;A[\\]b\nc\\\nd\t\te\\\\ \\\n\\]])", Just  $ Node [("A", ["]b cd  e\\ ]"])] []              ) ]
+            -- Within property values, whitespace characters such as tab are converted to spaces
+            , ("(;A[hello\t\tworld])"               , Just  $ Node [("A", ["hello  world"])] []              )
+            -- Within property values, newlines remain as newlines
+            , ("(;A[hello\n\nworld])"               , Just  $ Node [("A", ["hello\n\nworld"])] []            )
+            -- Escaped closing bracket within property value becomes just a closing bracket
+            , ("(;A[\\]])"                          , Just  $ Node [("A", ["]"])] []                         )
+            -- Escaped backslash in property value becomes just a backslash
+            , ("(;A[\\\\])"                         , Just  $ Node [("A", ["\\"])] []                        )
+            -- Opening bracket within property value doesn't need to be escaped
+            , ("(;A[x[y\\]z][foo]B[bar];C[baz])"    , Just  $ Node [("A", ["x[y]z", "foo"]), ("B", ["bar"])] [ Node [("C", ["baz"])] [] ] )
+            -- Semicolon in property value doesn't need to be escaped
+            , ("(;A[a;b][foo]B[bar];C[baz])"        , Just  $ Node [("A", ["a;b", "foo"]), ("B", ["bar"])] [ Node [("C", ["baz"])] [] ] )
+            -- Parentheses in property value doesn't need to be escaped
+            , ("(;A[x(y)z][foo]B[bar];C[baz])"      , Just  $ Node [("A", ["x(y)z", "foo"]), ("B", ["bar"])] [ Node [("C", ["baz"])] [] ] )
+            -- Escaped tab in property value is converted to space
+            , ("(;A[hello\\\tworld])"               , Just  $ Node [("A", ["hello world"])] []               )
+            -- Escaped newline in property value is converted to nothing at all
+            , ("(;A[hello\\\nworld])"               , Just  $ Node [("A", ["helloworld"])] []                )
+            -- Escaped t and n in property value are just letters, not whitespace
+            , ("(;A[\\t = t and \\n = n])"          , Just  $ Node [("A", ["t = t and n = n"])] []           )
+            -- mixing various kinds of whitespace and escaped characters in property value
+            , ("(;A[\\]b\nc\\\nd\t\te\\\\ \\\n\\]])", Just  $ Node [("A", ["]b\ncd  e\\ ]"])] []             ) ]
 
 -- b74debc3be24b5c81650189935c9bbfa019b367e