test frontmatter support

Author: m4rch3n1ng

test/corpus/source_files.txt

@@ -219,6 +219,80 @@ const ψ_2 : Ψ = 1;
     (type_identifier)
     (integer_literal)))
 
+================================================================================
+Frontmatter
+================================================================================
+
+#!/usr/bin/env cargo
+
+---
+[package]
+edition = "2024"
+---
+
+--------------------------------------------------------------------------------
+
+(source_file
+  (shebang)
+  (frontmatter
+    (frontmatter_content)))
+
+================================================================================
+Frontmatter with escaping
+================================================================================
+
+-----
+[package]
+description = """
+---
+---
+"""
+-----
+
+--------------------------------------------------------------------------------
+
+(source_file
+  (frontmatter
+    (frontmatter_content)))
+
+================================================================================
+Empty frontmatter
+================================================================================
+
+---
+---
+
+fn main() {}
+
+--------------------------------------------------------------------------------
+
+(source_file
+  (frontmatter
+    (frontmatter_content))
+  (function_item
+    (identifier)
+    (parameters)
+    (block)))
+
+================================================================================
+Empty frontmatter with info string
+================================================================================
+
+--- info string
+---
+
+fn main() {}
+
+--------------------------------------------------------------------------------
+
+(source_file
+  (frontmatter
+    (frontmatter_content))
+  (function_item
+    (identifier)
+    (parameters)
+    (block)))
+
 ================================================================================
 Shebang line containing spaces
 ================================================================================