feat(filesystem): Add read_file()

src/filesystem.rs

@@ -57,6 +57,18 @@ pub trait FileSystemEnv: Sync + Send + std::fmt::Debug {
         use std::fs::File;
         File::open(name).is_ok()
     }
+
+    fn read_file(&self, file_name: &str) -> std::io::Result<String> {
+        use std::fs::File;
+        use std::io::Read;
+
+        let path = self.in_cwd(file_name);
+        info!("reading from {:?}", path);
+        let mut file = File::open(path)?;
+        let mut content = String::new();
+        file.read_to_string(&mut content)?;
+        Ok(content)
+    }
 }
 
 #[derive(Clone, Debug, Default)]
@@ -125,4 +137,15 @@ mod tests {
         let env = RealFileSystemEnv::new(cwd.clone());
         assert_eq!(env.cwd(), &cwd);
     }
+
+    #[test_log::test]
+    fn test_write_and_read_file() -> std::io::Result<()> {
+        let env = TempFileSystemEnv::new()?;
+        let file_name = "test.txt";
+        let content = "Hello, World!";
+        let path = env.write_file(file_name, content)?;
+        assert_eq!(env.read_file(file_name)?, content);
+        assert!(path.exists());
+        Ok(())
+    }
 }