Additional tests

Additional tests for both parsing and evaluation. 100% passing as of
commit.

test/Spec.hs

@@ -80,6 +80,23 @@ parserTests = testGroup "Parser Tests"
       let input = "t (t t (t t))"
       let expected = TStem (TFork TLeaf (TStem TLeaf))
       parseSapling input @?= expected
+
+  , testCase "Parse empty list" $ do
+      let input = "[]"
+      let expected = SList []
+      parseSapling input @?= expected
+
+  , testCase "Parse multiple nested lists" $ do
+      let input = "[[t t] [t (t t)]]"
+      let expected = SList [SList [TLeaf, TLeaf], SList [TLeaf, TStem TLeaf]]
+      parseSapling input @?= expected
+
+  , testCase "Parse whitespace variance" $ do
+      let input1 = "[t    t]"
+      let input2 = "[ t  t ]"
+      let expected = SList [TLeaf, TLeaf]
+      parseSapling input1 @?= expected
+      parseSapling input2 @?= expected
   ]
 
 integrationTests :: TestTree
@@ -149,6 +166,20 @@ evaluationTests = testGroup "Evaluation Tests"
       let ast = parseSapling input
       (result $ evalSapling Map.empty ast) @?= toList [Leaf, Stem Leaf]
 
+  , testCase "Evaluate empty list" $ do
+      let input = "[]"
+      let ast = parseSapling input
+      (result $ evalSapling Map.empty ast) @?= toList []
+
+  , testCase "Evaluate variable dependency chain" $ do
+      let input = "x = t\ny = t x\nz = t y\nz"
+      let env = evalMulti Map.empty (parseMulti input)
+      (result env) @?= (Stem (Stem Leaf))
+
+  , testCase "Evaluate redefinition of variables" $ do
+      let input = "x = t t\nx = t\nx"
+      let env = evalMulti Map.empty (parseMulti input)
+      (result env) @?= Leaf
   ]
 
 propertyTests :: TestTree