Adding Files example to rustlings

exercises/files/README.md

@@ -0,0 +1,8 @@
+### Files
+The rust standard library supports reading files and writing them directly from the language!
+
+`std::fs::File` is just `A reference to an open file on the filesystem.`
+
+#### Book Sections
+
+- [Reading a file](https://doc.rust-lang.org/stable/book/ch12-02-reading-a-file.html)

exercises/files/files1.rs

@@ -0,0 +1,21 @@
+// files1.rs
+// Address all the TODOs to make the tests pass!
+
+// I AM NOT DONE
+
+use std::fs::File;
+use std::io::prelude::*;
+
+pub fn create_file() -> std::io::Result<()> {
+    let mut file = File::create("foo.txt")?;
+    file.write_all(b"Hello, world!")?;
+    Ok(())
+}
+
+
+
+#[test]
+fn read_file() {
+    create_file().unwrap();
+    //TODO: Read the file created above!
+}

info.toml

@@ -843,3 +843,9 @@ hint = """
 The implementation of FromStr should return an Ok with a Person object,
 or an Err with a string if the string is not valid.
 This is almost like the `try_from_into` exercise."""
+
+[[exercises]]
+name = "files"
+path = "exercises/files/files1.rs"
+mode = "test"
+hint = """Take a look at https://doc.rust-lang.org/std/fs/struct.File.html if you are stuck!"""