feat: make shell error comparable

src/error.rs

@@ -1,5 +1,6 @@
 use std::process::Command;
 
+#[derive(Debug)]
 pub enum ShellError {
     EmptyLine,
     Exit,
@@ -7,3 +8,15 @@ pub enum ShellError {
     ExecuteFailure(String),
     MalformedArgs(String),
 }
+
+impl PartialEq<Self> for ShellError {
+    fn eq(&self, other: &Self) -> bool {
+        match self {
+            &ShellError::EmptyLine => matches!(other, ShellError::EmptyLine),
+            &ShellError::Exit => matches!(other, ShellError::Exit),
+            &ShellError::NotFound(_) => matches!(other, ShellError::NotFound(_)),
+            &ShellError::ExecuteFailure(_) => matches!(other, ShellError::ExecuteFailure(_)),
+            &ShellError::MalformedArgs(_) => matches!(other, ShellError::MalformedArgs(_)),
+        }
+    }
+}