diff --git a/README.md b/README.md
index 66e0b1b..0dfed25 100644
--- a/README.md
+++ b/README.md
@@ -78,3 +78,7 @@ Once you have that installed, just run
 cargo build --release
 ```
 and you will find an executable in `target/release`.
+
+### Unit tests
+
+In order for the unit tests to pass, you will need `python3`
diff --git a/src/command.rs b/src/command.rs
index 3e3f5f1..be7431f 100644
--- a/src/command.rs
+++ b/src/command.rs
@@ -3,6 +3,7 @@ use crate::logger::{LogLevel, Logger};
 use std::error::Error;
 use std::fmt::{Display, Formatter};
 use std::io;
+use std::iter::once;
 use std::process::{Command, ExitStatus, Stdio};
 
 pub trait LogRunnable {
@@ -47,12 +48,20 @@ impl Display for SpecificExecutionError<'_> {
   fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
     write!(
       f,
-      "Failed to execute command {:?}: {}",
-      self.command, self.error
+      "Failed to execute command '{}': {}",
+      command_to_string(self.command),
+      self.error
     )
   }
 }
 
+fn command_to_string(command: &Command) -> String {
+  once(command.get_program().to_string_lossy())
+    .chain(command.get_args().map(|arg| arg.to_string_lossy()))
+    .collect::<Vec<_>>()
+    .join(" ")
+}
+
 impl Error for SpecificExecutionError<'_> {}
 
 #[derive(Debug)]
@@ -76,9 +85,9 @@ impl From<ExitStatus> for ExecutionError {
 impl Display for ExecutionError {
   fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
     match self {
-      ExecutionError::StartError(e) => write!(f, "failed to start command: {}", e),
+      ExecutionError::StartError(e) => write!(f, "Failed to start command: {}", e),
       ExecutionError::BadExitStatus(status) => {
-        write!(f, "command failed with exit status: {}", status)
+        write!(f, "Command failed with {}", status)
       }
     }
   }
@@ -90,23 +99,40 @@ impl Error for ExecutionError {}
 mod test {
   use crate::command::{ExecutionError, LogRunnable, SpecificExecutionError};
   use crate::logger::Logger;
+  use std::path::PathBuf;
   use std::process::Command;
 
   #[test]
   fn test_unknown_command() {
-    let mut command = Command::new("a_command_which_def_doesnt_exist");
+    let mut command = Command::new("python7");
     let Err(
       e @ SpecificExecutionError {
         error: ExecutionError::StartError(_),
         ..
       },
-    ) = command.args(["foo", "bar"]).run(&Logger::default())
+    ) = command
+      .args([PathBuf::from("test-ressources/python/exit_1.py")])
+      .run(&Logger::default())
     else {
       panic!("command shouldn't exist");
     };
-    println!("{e}");
+    assert_eq!(e.to_string(), "Failed to execute command 'python7': Failed to start command: No such file or directory (os error 2)");
   }
 
   #[test]
-  fn test_error() {}
+  fn test_error() {
+    let mut command = Command::new("python3");
+    let Err(
+      e @ SpecificExecutionError {
+        error: ExecutionError::BadExitStatus(_),
+        ..
+      },
+    ) = command
+      .arg("test-ressources/python/exit_1.py")
+      .run(&Logger::default())
+    else {
+      panic!("command should return exit-code 1")
+    };
+    assert_eq!(e.to_string(), "Failed to execute command 'python3 test-ressources/python/exit_1.py': Command failed with exit status: 1");
+  }
 }
diff --git a/src/logger.rs b/src/logger.rs
index 89226b6..57ddae5 100644
--- a/src/logger.rs
+++ b/src/logger.rs
@@ -39,7 +39,7 @@ macro_rules! log {
     $logger.$level(format!($($args)*));
   };
   ($logger:expr, $($args:tt)*) => {
-    log!($logger, info, $($args)*);
+    log!($logger, info, $($args)*); //TODO better use default level with log function instead of assuming info as default
   }
 }
 
diff --git a/test-ressources/python/exit_1.py b/test-ressources/python/exit_1.py
new file mode 100644
index 0000000..b11a11b
--- /dev/null
+++ b/test-ressources/python/exit_1.py
@@ -0,0 +1 @@
+exit(1)
\ No newline at end of file