krops: add allocateTTY to writeDeploy

With allocateTTY, nixos-rebuild runs with a terminal, so it shows colours
and progress: on remote targets, ssh gets -t, which allocates a terminal
if its own input is one, and on the local target, expect's unbuffer
provides one.

The nixos-rebuild stand-in records whether its output is a terminal.

2 files changed, 26 insertions, 3 deletions

diff --git a/tests/nixos-rebuild.sh b/tests/nixos-rebuild.sh
index 9e2e47e..ec0c85c 100755
--- a/tests/nixos-rebuild.sh
+++ b/tests/nixos-rebuild.sh
@@ -1,8 +1,10 @@
 #! /bin/sh
-# Stands in for nixos-rebuild: records the user it runs as, NIX_PATH, and its
-# arguments in /tmp/nixos-rebuild.log.
+# Stands in for nixos-rebuild: records the user it runs as, NIX_PATH, its
+# arguments, and whether its output is a terminal in /tmp/nixos-rebuild.log.
+if test -t 1; then terminal=terminal; else terminal='no terminal'; fi
 {
   id -u
   printf '%s\n' "${NIX_PATH-}"
   printf '%s\n' "$*"
+  echo "$terminal"
 } > /tmp/nixos-rebuild.log
diff --git a/tests/scenarios.nix b/tests/scenarios.nix
index e618fcd..2fc1bd7 100644
--- a/tests/scenarios.nix
+++ b/tests/scenarios.nix
@@ -786,7 +786,28 @@ assert !(krops.isLocalTarget (targets.remote "/"));
           expect_eq arguments "$(sed -n 3p /tmp/nixos-rebuild.log)" "$expected"
         '';
       };
-    });
+    })
+
+  # writeDeploy with allocateTTY: nixos-rebuild's output is a terminal on
+  # the local target.  ssh allocates one on remote targets only if its own
+  # input is a terminal, which the tests' isn't.
+  ++ map (targetKind: scenario {
+    name = "deploy-${targetKind}-allocateTTY";
+    inherit targetKind;
+    prepare = ''
+      rm -f /tmp/nixos-rebuild.log /etc/nixos/flake.nix
+    '';
+    phases = [{
+      sources.x.file = "/fixtures/alt";
+      deploy.allocateTTY = true;
+      check = ''
+        expect_eq arguments "$(sed -n 3p /tmp/nixos-rebuild.log)" switch
+        expect_eq terminal "$(sed -n 4p /tmp/nixos-rebuild.log)" ${
+          if targetKind == "local" then "terminal" else "'no terminal'"
+        }
+      '';
+    }];
+  }) targetKinds;
 
   # Features spanning several sources.
   features = concatMap (targetKind: let