Add test subcommand

Co-Authored-By: Timothy Clem <timothy.clem@gmail.com>

cli/src/error.rs

@@ -1,3 +1,5 @@
+use std::io;
+
 #[derive(Debug)]
 pub struct Error(pub String);
 
@@ -22,3 +24,15 @@ impl From<serde_json::Error> for Error {
         Error(error.to_string())
     }
 }
+
+impl From<io::Error> for Error {
+    fn from(error: io::Error) -> Self {
+        Error(error.to_string())
+    }
+}
+
+impl From<String> for Error {
+    fn from(error: String) -> Self {
+        Error(error)
+    }
+}