tests: add stderr comparison to the test suite

The code is more or less copied from the stdout comparison code, maybe
some better reuse is possible.

test 1457 is adjusted to make the output actually match (by using --silent)
test 506 used <stderr> without actually needing it, so that <stderr> block is removed

Closes #3536

tests/data/test1457

@@ -29,7 +29,7 @@ http
 Check if %{stderr} and %{stdout} switch between stdout and stderr.
 </name>
 <command>
-http://%HOSTIP:%HTTPPORT/1457 --write-out 'line1%{stderr}line2%{stdout}line3'
+http://%HOSTIP:%HTTPPORT/1457 --silent --write-out 'line1%{stderr}line2%{stdout}line3'
 </command>
 </client>
 

tests/data/test506

@@ -228,9 +228,6 @@ lock:   share  [Pigs in space]: 94
 unlock: share  [Pigs in space]: 95
 GLOBAL_CLEANUP
 </stdout>
-<stderr>
-http://%HOSTIP:%HTTPPORT/506 
-</stderr>
 <file name="log/jar506" mode="text">
 # Netscape HTTP Cookie File
 # https://curl.haxx.se/docs/http-cookies.html

tests/runtests.pl

@@ -6,7 +6,7 @@
 #                            | (__| |_| |  _ <| |___
 #                             \___|\___/|_| \_\_____|
 #
-# Copyright (C) 1998 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al.
+# Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
 #
 # This software is licensed as described in the file COPYING, which
 # you should have received as part of this distribution. The terms
@@ -3746,6 +3746,7 @@ sub singletest {
 
     # if this section exists, we verify that the stdout contained this:
     my @validstdout = fixarray ( getpart("verify", "stdout") );
+    my @validstderr = fixarray ( getpart("verify", "stderr") );
 
     # if this section exists, we verify upload
     my @upload = getpart("verify", "upload");
@@ -4229,6 +4230,57 @@ sub singletest {
         $ok .= "-"; # stdout not checked
     }
 
+    if (@validstderr) {
+        # verify redirected stderr
+        my @actual = loadarray($STDERR);
+
+        # what parts to cut off from stderr
+        my @stripfile = getpart("verify", "stripfile");
+
+        foreach my $strip (@stripfile) {
+            chomp $strip;
+            my @newgen;
+            for(@actual) {
+                eval $strip;
+                if($_) {
+                    push @newgen, $_;
+                }
+            }
+            # this is to get rid of array entries that vanished (zero
+            # length) because of replacements
+            @actual = @newgen;
+        }
+
+        # variable-replace in the stderr we have from the test case file
+        @validstderr = fixarray(@validstderr);
+
+        # get all attributes
+        my %hash = getpartattr("verify", "stderr");
+
+        # get the mode attribute
+        my $filemode=$hash{'mode'};
+        if($filemode && ($filemode eq "text") && $has_textaware) {
+            # text mode when running on windows: fix line endings
+            map s/\r\n/\n/g, @validstderr;
+            map s/\n/\r\n/g, @validstderr;
+        }
+
+        if($hash{'nonewline'}) {
+            # Yes, we must cut off the final newline from the final line
+            # of the protocol data
+            chomp($validstderr[$#validstderr]);
+        }
+
+        $res = compare($testnum, $testname, "stderr", \@actual, \@validstderr);
+        if($res) {
+            return 1;
+        }
+        $ok .= "r";
+    }
+    else {
+        $ok .= "-"; # stderr not checked
+    }
+
     if(@protocol) {
         # Verify the sent request
         my @out = loadarray($SERVERIN);