Set readline-relevant ENV vars in interactive_psql(), not caller.

Commit 664d75753 pulled 010_tab_completion.pl's infrastructure for
invoking an interactive psql session out into a generally-useful test
function, but it didn't move enough stuff.  We need to set up various
environment variables that readline will look at, both to ensure
stability of test results and to prevent test actions from cluttering
the calling user's ~/.psql_history.  Expecting calling scripts to
remember to do that is too failure-prone: the other existing caller
001_password.pl did not do it.  Hence, remove those initialization
steps from 010_tab_completion.pl and put them into interactive_psql().
Since interactive_psql was already making a local ENV hash, this has
no effect on calling scripts.

Discussion: https://postgr.es/m/794610.1703182896@sss.pgh.pa.us

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

src/test/perl/PostgreSQL/Test/Cluster.pm

@@ -2048,14 +2048,17 @@ 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 B</dev/null>.
+
 =back
 
 This requires IO::Pty in addition to IPC::Run.
@@ -2068,6 +2071,27 @@ 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.
+	$ENV{PSQL_HISTORY} = $params{history_file} || '/dev/null';
+
+	# 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));