add whitespace tests

corpus/annotation.txt

@@ -1,3 +1,29 @@
+==================
+empty nix-shell
+==================
+
+#!/usr/bin/env nix-shell
+#!nix-shell
+---
+
+(source_file
+  (first_line)
+  (next_line
+    (annotation_line)))
+
+==================
+whitespace in nix-shell
+==================
+
+#!/usr/bin/env nix-shell
+#! nix-shell
+---
+
+(source_file
+  (first_line)
+  (next_line
+    (annotation_line)))
+
 ==================
 minimal nix-shell invocation with interpreter
 ==================
@@ -88,19 +114,6 @@ order-independent
         (interpreter
           (sh_arg))))))
 
-==================
-empty nix-shell
-==================
-
-#!/usr/bin/env nix-shell
-#!nix-shell
----
-
-(source_file
-  (first_line)
-  (next_line
-    (annotation_line)))
-
 ==================
 multiple annotation lines
 ==================

corpus/shebang.txt

@@ -7,3 +7,13 @@ nix-shell shebang without any interpreter option
 
 (source_file
   (first_line))
+
+==================
+nix-shell shebang whitespace
+==================
+
+#! /usr/bin/env nix-shell
+---
+
+(source_file
+  (first_line))