Re: authentication/t/001_password.pl trashes ~/.psql_history

I wrote:
> I happened to notice this stuff getting added to my .psql_history:
> \echo background_psql: ready
> SET password_encryption='scram-sha-256';
> ;
> \echo background_psql: QUERY_SEPARATOR
> SET scram_iterations=42;
> ;
> \echo background_psql: QUERY_SEPARATOR
> \password scram_role_iter
> \q

> After grepping for these strings, this is evidently the fault of
> src/test/authentication/t/001_password.pl by way of BackgroundPsql.pm,
> which fires up an interactive psql run that is not given the -n switch.

> Currently the only other user of interactive_psql() seems to be
> psql/t/010_tab_completion.pl, which avoids this problem by
> explicitly redirecting the history file.  We could have 001_password.pl
> do likewise, or we could have it pass the -n switch, but I think we're
> going to have this problem resurface repeatedly if we leave it to the
> outer test script to remember to do it.


After studying this some more, my conclusion is that BackgroundPsql.pm
failed to borrow as much as it should have from 010_tab_completion.pl.
Specifically, we want all the environment-variable changes that that
script performed to be applied in any test using an interactive psql.
Maybe ~/.inputrc and so forth would never affect any other test scripts,
but that doesn't seem like a great bet.

So that leads me to the attached proposed patch.

            regards, tom lane

diff --git a/src/bin/psql/t/010_tab_completion.pl b/src/bin/psql/t/010_tab_completion.pl
index 4cd0fa4680..f2d2809aef 100644
--- a/src/bin/psql/t/010_tab_completion.pl
+++ b/src/bin/psql/t/010_tab_completion.pl
@@ -46,25 +46,6 @@ $node->safe_psql('postgres',
       . "CREATE TYPE enum1 AS ENUM ('foo', 'bar', 'baz', 'BLACK');\n"
       . "CREATE PUBLICATION some_publication;\n");

-# Developers would not appreciate this test adding a bunch of junk to
-# their ~/.psql_history, so be sure to redirect history into a temp file.
-# We might as well put it in the test log directory, so that buildfarm runs
-# capture the result for possible debugging purposes.
-my $historyfile = "${PostgreSQL::Test::Utils::log_path}/010_psql_history.txt";
-$ENV{PSQL_HISTORY} = $historyfile;
-
-# Another pitfall for developers is that they might have a ~/.inputrc
-# file that changes readline's behavior enough to affect this test.
-# So ignore any such file.
-$ENV{INPUTRC} = '/dev/null';
-
-# Unset $TERM so that readline/libedit won't use any terminal-dependent
-# escape sequences; that leads to way too many cross-version variations
-# in the output.
-delete $ENV{TERM};
-# Some versions of readline inspect LS_COLORS, so for luck unset that too.
-delete $ENV{LS_COLORS};
-
 # In a VPATH build, we'll be started in the source directory, but we want
 # to run in the build directory so that we can use relative paths to
 # access the tab_comp_dir subdirectory; otherwise the output from filename
@@ -91,8 +72,13 @@ open $FH, ">", "tab_comp_dir/afile456"
 print $FH "other stuff\n";
 close $FH;

+# Arrange to capture, not discard, the interactive session's history output.
+# Put it in the test log directory, so that buildfarm runs capture the result
+# for possible debugging purposes.
+my $historyfile = "${PostgreSQL::Test::Utils::log_path}/010_psql_history.txt";
+
 # fire up an interactive psql session
-my $h = $node->interactive_psql('postgres');
+my $h = $node->interactive_psql('postgres', history_file => $historyfile);

 # Simple test case: type something and see if psql responds as expected
 sub check_completion
diff --git a/src/test/perl/PostgreSQL/Test/Cluster.pm b/src/test/perl/PostgreSQL/Test/Cluster.pm
index f43e54282f..4d207730c9 100644
--- a/src/test/perl/PostgreSQL/Test/Cluster.pm
+++ b/src/test/perl/PostgreSQL/Test/Cluster.pm
@@ -2128,14 +2128,17 @@ Errors occurring later are the caller's problem.

 Be sure to "quit" the returned object when done with it.

-The only extra parameter currently accepted is
-
 =over

 =item extra_params => ['--single-transaction']

 If given, it must be an array reference containing additional parameters to B<psql>.

+=item history_file => B<path>
+
+Cause the interactive B<psql> session to write its command history to B<path>.
+If not given, the history is sent to /dev/null.
+
 =back

 This requires IO::Pty in addition to IPC::Run.
@@ -2148,6 +2151,29 @@ sub interactive_psql

     local %ENV = $self->_get_env();

+    # Since the invoked psql will believe it's interactive, it will use
+    # readline/libedit if available.  We need to adjust some environment
+    # settings to prevent unwanted side-effects.
+
+    # Developers would not appreciate tests adding a bunch of junk to
+    # their ~/.psql_history, so redirect readline history somewhere else.
+    # If the calling script doesn't specify anything, just bit-bucket it.
+    my $history_file = $params{history_file};
+    $history_file ||= '/dev/null';
+    $ENV{PSQL_HISTORY} = $history_file;
+
+    # Another pitfall for developers is that they might have a ~/.inputrc
+    # file that changes readline's behavior enough to affect the test.
+    # So ignore any such file.
+    $ENV{INPUTRC} = '/dev/null';
+
+    # Unset $TERM so that readline/libedit won't use any terminal-dependent
+    # escape sequences; that leads to way too many cross-version variations
+    # in the output.
+    delete $ENV{TERM};
+    # Some versions of readline inspect LS_COLORS, so for luck unset that too.
+    delete $ENV{LS_COLORS};
+
     my @psql_params = (
         $self->installed_command('psql'),
         '-XAt', '-d', $self->connstr($dbname));