nixos/tests: fix succeed() with multiple commands

we previously immediately returned the first commands output, and didn't
execute any of the other commands.

Now, return the last commands output.
This should be documented in the method docstring.

1 files changed, 5 insertions, 3 deletions

diff --git a/nixos/lib/test-driver/test-driver.py b/nixos/lib/test-driver/test-driver.py
index c8940d78af4ec..c8d4936ac52a1 100644
--- a/nixos/lib/test-driver/test-driver.py
+++ b/nixos/lib/test-driver/test-driver.py
@@ -381,15 +381,17 @@ class Machine:
 
     def succeed(self, *commands):
         """Execute each command and check that it succeeds."""
+        output = ""
         for command in commands:
             with self.nested("must succeed: {}".format(command)):
-                status, output = self.execute(command)
+                (status, out) = self.execute(command)
                 if status != 0:
-                    self.log("output: {}".format(output))
+                    self.log("output: {}".format(out))
                     raise Exception(
                         "command `{}` failed (exit code {})".format(command, status)
                     )
-                return output
+                output += out
+        return output
 
     def fail(self, *commands):
         """Execute each command and check that it fails."""