test(rustfmt): Verify frontmatter is preserved

This is to prove that the frontmatter is preserved. The choices in tests is intended for showing the different parts of the proposed Style Guide for frontmatters.

src/tools/rustfmt/tests/source/frontmatter_compact.rs

@@ -0,0 +1,8 @@
+#!/usr/bin/env cargo
+---identifier
+[dependencies]
+regex = "1"
+---
+#![feature(frontmatter)]
+
+fn main() {}

src/tools/rustfmt/tests/source/frontmatter_escaped.rs

@@ -0,0 +1,13 @@
+#!/usr/bin/env cargo
+------------
+package.description = """
+Header
+-----
+
+Body
+"""
+------------
+
+#![feature(frontmatter)]
+
+fn main() {}

src/tools/rustfmt/tests/source/frontmatter_spaced.rs

@@ -0,0 +1,16 @@
+#!/usr/bin/env cargo
+
+
+--- identifier
+[dependencies]
+regex = "1"
+
+---
+
+
+
+
+
+#![feature(frontmatter)]
+
+fn main() {}

src/tools/rustfmt/tests/target/frontmatter_compact.rs

@@ -0,0 +1,8 @@
+#!/usr/bin/env cargo
+---identifier
+[dependencies]
+regex = "1"
+---
+#![feature(frontmatter)]
+
+fn main() {}

src/tools/rustfmt/tests/target/frontmatter_escaped.rs

@@ -0,0 +1,13 @@
+#!/usr/bin/env cargo
+------------
+package.description = """
+Header
+-----
+
+Body
+"""
+------------
+
+#![feature(frontmatter)]
+
+fn main() {}

src/tools/rustfmt/tests/target/frontmatter_spaced.rs

@@ -0,0 +1,16 @@
+#!/usr/bin/env cargo
+
+
+--- identifier
+[dependencies]
+regex = "1"
+
+---
+
+
+
+
+
+#![feature(frontmatter)]
+
+fn main() {}