Merge "Merge pull request NixOS#10799 from hercules-ci/safer-tab-comp…

…letion" into main

flake.nix

@@ -233,6 +233,11 @@
           }
         );
 
+        # Completion tests for the Nix REPL.
+        repl-completion = forAllSystems (
+          system: nixpkgsFor.${system}.native.callPackage ./tests/repl-completion.nix { }
+        );
+
         # Perl bindings for various platforms.
         perlBindings = forAllSystems (system: nixpkgsFor.${system}.native.nix.passthru.perl-bindings);
 
@@ -330,6 +335,7 @@
           rl-next = self.hydraJobs.rl-next.${system}.user;
           # Will be empty attr set on i686-linux, and filtered out by forAvailableSystems.
           pre-commit = self.hydraJobs.pre-commit.${system};
+          repl-completion = self.hydraJobs.repl-completion.${system};
         }
         // (lib.optionalAttrs (builtins.elem system linux64BitSystems)) {
           dockerImage = self.hydraJobs.dockerImage.${system};

tests/repl-completion.nix

@@ -0,0 +1,40 @@
+{ runCommand, nix, expect }:
+
+# We only use expect when necessary, e.g. for testing tab completion in nix repl.
+# See also tests/functional/repl.sh
+
+runCommand "repl-completion" {
+  nativeBuildInputs = [
+    expect
+    nix
+  ];
+  expectScript = ''
+    # Regression https://github.com/NixOS/nix/pull/10778
+    spawn nix repl --offline --extra-experimental-features nix-command
+    expect "nix-repl>"
+    send "foo = import ./does-not-exist.nix\n"
+    expect "nix-repl>"
+    send "foo.\t"
+    expect {
+      "nix-repl>" {
+        puts "Got another prompt. Good."
+      }
+      eof {
+        puts "Got EOF. Bad."
+        exit 1
+      }
+    }
+    exit 0
+  '';
+  passAsFile = [ "expectScript" ];
+}
+''
+  export NIX_STORE=$TMPDIR/store
+  export NIX_STATE_DIR=$TMPDIR/state
+  export HOME=$TMPDIR/home
+  mkdir $HOME
+
+  nix-store --init
+  expect $expectScriptPath
+  touch $out
+''