diff --git a/http/web.py b/http/web.py
index fb63e23..c8c39d9 100755
--- a/http/web.py
+++ b/http/web.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/env python3
 
 #  This file is part of Elixir, a source code cross-referencer.
 #
@@ -310,7 +310,7 @@ if mode == 'source':
 elif mode == 'ident':
     data['title'] = ident+' identifier - '+title_suffix
 
-    symbol_definitions, symbol_references, symbol_doccomments_UNUSED = query('ident', tag, ident, family)
+    symbol_definitions, symbol_references, symbol_doccomments = query('ident', tag, ident, family)
 
     print('<div class="lxrident">')
     if len(symbol_definitions):
@@ -322,6 +322,16 @@ elif mode == 'ident':
             ))
         print('</ul>')
 
+        if len(symbol_doccomments):
+            print('<h2>Documented in '+str(len(symbol_doccomments))+' files:</h2>')
+            print('<ul>')
+            for symbol_doccomment in symbol_doccomments:
+                print('<li><a href="{v}/source/{f}#L{n}"><strong>{f}</strong>, line {n}</a></li>'.format(
+                    v=version, f=symbol_doccomment.path, n=symbol_doccomment.line
+                ))
+            print('</ul>')
+
+
         print('<h2>Referenced in '+str(len(symbol_references))+' files:</h2>')
         print('<ul>')
         for symbol_reference in symbol_references:
@@ -361,7 +371,7 @@ if status == 404:
     realprint('Status: 404 Not Found')
 
 import jinja2
-loader = jinja2.FileSystemLoader(os.path.join(os.path.dirname(__file__), '../templates/'))
+loader = jinja2.FileSystemLoader(os.path.join(os.path.dirname(os.path.realpath(__file__)), '../templates/'))
 environment = jinja2.Environment(loader=loader)
 template = environment.get_template('layout.html')
 
diff --git a/t/050-testhelpers.t b/t/050-testhelpers.t
new file mode 100644
index 0000000..0840085
--- /dev/null
+++ b/t/050-testhelpers.t
@@ -0,0 +1,57 @@
+#!/usr/bin/env perl
+# t/50-testhelpers.t: test TestHelpers.pm
+#
+# Copyright (c) 2020 Christopher White, <cxwembedded@gmail.com>.
+# Copyright (c) 2020 D3 Engineering, LLC.
+#
+# Elixir is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Elixir is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+# # You should have received a copy of the GNU Affero General Public License
+# along with Elixir.  If not, see <http://www.gnu.org/licenses/>.
+#
+# SPDX-License-Identifier: AGPL-3.0-or-later
+#
+# This file uses core Perl modules only.
+
+use FindBin '$Bin';
+use lib $Bin;
+
+use Test::More;
+
+use TestEnvironment;
+use TestHelpers qw(:all);
+
+# === line_mark_string =======================================================
+
+our ($fn, $refln, $ln);
+
+sub level1 {
+    eval line_mark_string 1, '$fn = __FILE__; $ln = __LINE__';
+    ok !$@, 'level1 no errors';
+}
+
+$refln = __LINE__; level1;
+is $fn, __FILE__, 'level1 file';
+cmp_ok $ln, '==', $refln, 'level1 line';
+
+sub level2 {
+    level2_inner();
+}
+
+sub level2_inner {
+    eval line_mark_string 2, '$fn = __FILE__; $ln = __LINE__';
+    ok !$@, 'level2_inner no errors';
+}
+
+$refln = __LINE__; level2;
+is $fn, __FILE__, 'level2 file';
+cmp_ok $ln, '==', $refln, 'level2 line';
+
+done_testing;
diff --git a/t/400-web.t b/t/400-web.t
new file mode 100644
index 0000000..be5a915
--- /dev/null
+++ b/t/400-web.t
@@ -0,0 +1,80 @@
+#!/usr/bin/env perl
+# t/400-web.pl: Test web.py
+#
+# Copyright (c) 2020 Christopher White, <cxwembedded@gmail.com>.
+#
+# Elixir is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Elixir is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+# # You should have received a copy of the GNU Affero General Public License
+# along with Elixir.  If not, see <http://www.gnu.org/licenses/>.
+#
+# SPDX-License-Identifier: AGPL-3.0-or-later
+#
+# This file uses core Perl modules only.
+
+use FindBin '$Bin';
+use lib $Bin;
+
+use Test::More;
+
+use TestEnvironment;
+use TestHelpers;
+
+# ===========================================================================
+# Main
+
+# Set up for the tests
+my $tenv = TestEnvironment->new;
+$tenv->build_repo(sibling_abs_path('tree'));	# dies on error
+$tenv->build_db;
+$tenv->update_env;
+
+diag $tenv->report;
+
+http_request_ok 'index query', $tenv, '/testproj/latest/source',
+    [ qr{^Content-Type:\s*text/html}, qr{href="latest/source/issue102.c"},
+        qr{href="latest/source/arch"} ], 1;
+
+http_request_ok 'identifier query', $tenv, '/testproj/v5.4/ident/gsb_buffer',
+    [ qr{^Content-Type:\s*text/html}, qr{\bgsb_buffer\b},
+        qr{"v5.4/source/drivers/i2c/i2c-core-acpi.c\#L23".+?
+            drivers/i2c/i2c-core-acpi.c.+?
+            line[ ]23.+?
+            \bstruct\b}x ], 1;
+
+# Doc comments: testcases pulled from t/300
+http_request_ok 'doc-comment query (nonexistent)', $tenv,
+    '/testproj/v5.4/ident/SOME_NONEXISTENT_IDENTIFIER_XYZZY_PLUGH',
+    [ qr{^Content-Type:\s*text/html}, qr{<h\d>Identifier not used</h\d>}i], 1;
+
+http_request_ok 'doc-comment query (existent but not documented)', $tenv,
+    '/testproj/v5.4/ident/gsb_buffer',   # in drivers/i2c/i2c-core-acpi.c
+    [
+        qr{^Content-Type:\s*text/html},
+        { not => qr{\bDocumented in\b} },
+    ], 1;
+
+http_request_ok 'ident query (existent, function, documented in C file)', $tenv,
+    '/testproj/v5.4/ident/i2c_acpi_get_i2c_resource',
+    [
+        qr{^Content-Type:\s*text/html},
+        qr{\bDocumented in \d},
+        {doc => qr{drivers/i2c/i2c-core-acpi\.c.+\b45\b}},
+    ], 1;
+
+http_request_ok 'ident query (existent, function, documented in C file, #102)',
+    $tenv, '/testproj/v5.4/ident/documented_function_XYZZY',
+    [
+        qr{^Content-Type:\s*text/html},
+        qr{\bDocumented in \d},
+        {doc => qr{issue102\.c.+\b6\b}},
+    ], 1;
+
+done_testing;
diff --git a/t/TestEnvironment.pm b/t/TestEnvironment.pm
index 8a03d6c..8237671 100644
--- a/t/TestEnvironment.pm
+++ b/t/TestEnvironment.pm
@@ -246,6 +246,7 @@ sub make_web_request {
     $self->update_env;  # just in case
 
     local $ENV{REQUEST_URI} = $url;
+    diag "Requesting `$url'";
     my ($exit_status, $lrStdout, $lrStderr) = run_program($self->web_py);
 
     if(!wantarray) {
diff --git a/t/TestHelpers.pm b/t/TestHelpers.pm
index f706969..4d49037 100644
--- a/t/TestHelpers.pm
+++ b/t/TestHelpers.pm
@@ -43,7 +43,7 @@ use parent 'Exporter';
 our (@EXPORT, @EXPORT_OK, %EXPORT_TAGS);
 BEGIN {
     @EXPORT = qw(sibling_abs_path find_program run_program ok_or_die
-                run_produces_ok MUST_SUCCEED);
+                run_produces_ok http_request_ok MUST_SUCCEED);
     @EXPORT_OK = qw(line_mark_string);
     %EXPORT_TAGS = (
         all => [@EXPORT, @EXPORT_OK],
@@ -142,9 +142,9 @@ for consistency with bash (L<https://tldp.org/LDP/abs/html/exitcodes.html>).
 =cut
 
 sub _run_and_capture;   # forward
+sub _check_queries;     # forward
 
 sub run_program {
-    diag "Running @_";
 
     if(wantarray) {
         goto &_run_and_capture;
@@ -152,6 +152,7 @@ sub run_program {
 
     my $errmsg;
 
+    diag "Running @_";
     my $status = system(@_);
 
     if ($status == -1) {
@@ -199,7 +200,7 @@ EOT
 Run a program and check whether it produces expected output.
 Usage:
 
-    run_produces_ok($desc, \@program_and_args, \@expected_regexes,
+    run_produces_ok($desc, \@program_and_args, \@conditions,
                     <optional> $mustSucceed, <optional> $printOutput)
 
 The test passes if each condition in C<@conditions> is true.
@@ -286,27 +287,51 @@ sub _run_and_capture {
 } #_run_and_capture()
 
 sub run_produces_ok {
-    my ($desc, $lrProgram, $lrRegexes, $mustSucceed, $printOutput) = @_;
+    my ($desc, $lrProgram, $lrConditions, $mustSucceed, $printOutput) = @_;
 
     my ($exit_status, $outlines, $errlines) = _run_and_capture(@$lrProgram);
-    my @outlines = @$outlines;
-    my @errlines = @$errlines;
+
+    _check_queries($desc, $lrConditions, $mustSucceed, $printOutput, $exit_status, $outlines, $errlines);
+} #run_produces_ok()
+
+sub _check_queries {
+    my ($desc, $lrConditions, $mustSucceed, $printOutput, $exit_status, $lrStdout, $lrStderr) = @_;
+
+    my @outlines = @$lrStdout;
+    my @errlines = @$lrStderr;
 
     if ($printOutput) {
         diag "@outlines";
     }
 
+    # Check for and report Python errors
+    foreach(@outlines, @errlines) {
+        if (/^.*?(\S+)\s+contains the description of this error/) {
+            my $logfn = $1;
+
+            no autodie;
+            open my $logfh, '<', $logfn
+                or warn("Could not open Python log file $logfn: $!"), last;
+            my $logtext = do { local $/; <$logfh> };
+            close $logfh;
+
+            diag "Python error log $logfn:\n$logtext";
+            last;
+        }
+    }
+
     # Basic checks
     if($mustSucceed) {
-        eval line_mark_string 1, <<'EOT';
+        eval line_mark_string 2, <<'EOT';
         cmp_ok($exit_status, '==', 0, "$desc: exit status 0");
         cmp_ok(@errlines, '==', 0, "$desc: stderr empty");
 EOT
+        die $@ if $@;
     }
 
     # Check regexes
     my %query_py_output;    # filled in only if we see a def/ref/doc
-    for my $entry (@$lrRegexes) {
+    for my $entry (@$lrConditions) {
         my ($re, $negated, $source) = _parse_condition($entry);
 
         # Parse query.py output if we need it and haven't done so
@@ -326,12 +351,42 @@ EOT
         $test .= ($negated ? ' excludes ' : ' includes ') . "\Q$re\E" . '");';
 
         # Run it
-        #diag "Running $test";
-        eval line_mark_string 1, $test;
+        eval line_mark_string 2, $test;
+        die $@ if $@;
     } #foreach $entry
 
 } #run_produces_ok()
 
+=head2 http_request_ok
+
+Run C<web.py> against a given path and check whether it produces expected
+output.  Usage:
+
+    http_request_ok($desc, $tenv, $path, \@conditions, <optional> $printOutput)
+
+The test passes if the HTTP request succeeds, and if each condition in
+C<@conditions> is true of the result (headers and body).
+
+C<$tenv> is a L<TestEnvironment>.
+
+C<$path> is the path part of the URL, e.g., C</testproj/latest/source>.
+
+See L</run_produces_ok> for C<@conditions>.
+
+If C<$printOutput> is true, prints the output of C<@program_and_args>.
+
+=cut
+
+sub http_request_ok {
+    my ($desc, $tenv, $path, $lrConditions, $printOutput) = @_;
+    die "Invalid args" unless $desc && ref $tenv && eval { @$lrConditions };
+
+    my ($exit_status, $lrStdout, $lrStderr) = $tenv->make_web_request($path);
+
+    _check_queries($desc, $lrConditions, MUST_SUCCEED, $printOutput,
+        $exit_status, $lrStdout, $lrStderr);
+} #http_request_ok()
+
 =head1 INTERNAL FUNCTIONS
 
 These are ones you probably won't need to call.
@@ -349,16 +404,17 @@ sub _parseq {
     my $list;
     foreach(@_) {
         chomp;
-        if($_ eq 'Symbol Definitions:') {
+        if(/(?:^Symbol Definitions:$)|\bDefined in \d+/) {
             $list = 'def';
             next;
-        } elsif($_ eq 'Symbol References:') {
+        } elsif(/(?:^Symbol References:$)|\bReferenced in \d+/) {
             $list = 'ref';
             next;
-        } elsif($_ eq 'Documented in:') {
+        } elsif(/(?:^Documented in:$)|\bDocumented in \d+/) {
             $list = 'doc';
             next;
         }
+        next unless $list;
 
         #diag "Adding `$_' to list $list";
         push @{$retval{$list}}, $_;