Add regression test

Author: yannham

topiary-cli/tests/samples/expected/nickel.ncl

@@ -139,7 +139,20 @@
         1
       else
         3
-    )
+    ),
+
+    # regression test for https://github.com/tweag/topiary/issues/743
+    # (partially fixed)
+    let foo
+      | Number
+      = [
+        1,
+        2,
+        3
+      ]
+    in
+    foo
+    @ [],
   ],
 
   # Nickel standard library as of 44aef1672a09a76a71946fbf822713747ab7b9df

topiary-cli/tests/samples/input/nickel.ncl

@@ -127,7 +127,21 @@ bar == 'Goodbye
           if x == 1 then
               1
 else
-    3)
+    3),
+
+    # regression test for https://github.com/tweag/topiary/issues/743
+    # (partially fixed)
+    let foo
+    | Number
+    =
+[
+    1,
+    2,
+    3
+]
+in
+foo
+@ [],
   ],
 
   # Nickel standard library as of 44aef1672a09a76a71946fbf822713747ab7b9df