audiotestsrc: Fix the way we compute EOS in reverse playback

In reverse playback we were not taking into account the current buffer
samples to check if we had reached EOS which was leading to a buffer
with PTS = CLOCK_TIME_NONE containing too many frames followed by a
useless buffer with pts=0 duration=0, and a g_critical issue in
gst_object_sync_values.

Also add a validate based test case.
Without that patch this is how the expectation fails:

``` diff
--- log-asink-sink-expected       2020-05-22 23:22:42.654384579 -0400
+++ log-asink-sink-actual  2020-05-22 23:29:35.671586380 -0400
@@ -27,5 +27,6 @@
 buffer: pts=0:00:00.058820861, due=0:00:00.023219955, flags=discont
 buffer: pts=0:00:00.035600907, due=0:00:00.023219954, flags=discont
 buffer: pts=0:00:00.012380952, due=0:00:00.023219955, flags=discont
-buffer: pts=0:00:00.000000000, due=0:00:00.012380952, flags=discont
+buffer: due=0:00:00.012380953, flags=discont
+buffer: pts=0:00:00.000000000, flags=discont
 event eos: (no structure)
 ```

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/667>

gst/audiotestsrc/gstaudiotestsrc.c

@@ -1489,10 +1489,10 @@ gst_audio_test_src_fill (GstBaseSrc * basesrc, guint64 offset,
     next_sample = src->sample_stop;
     src->eos_reached = TRUE;
   } else if (src->check_seek_stop && src->reverse &&
-      (src->sample_stop > src->next_sample)
+      (src->sample_stop >= (src->next_sample - samples))
       ) {
     /* calculate only partial buffer */
-    src->generate_samples_per_buffer = src->sample_stop - src->next_sample;
+    src->generate_samples_per_buffer = src->next_sample - src->sample_stop;
     next_sample = src->sample_stop;
     src->eos_reached = TRUE;
   } else {

meson_options.txt

@@ -87,3 +87,5 @@ option('package-origin', type : 'string', value : 'Unknown package origin', yiel
        description : 'package origin URL to use in plugins')
 option('doc', type : 'feature', value : 'auto', yield: true,
        description: 'Enable documentation.')
+option('validate', type : 'feature', value : 'auto', yield: true,
+       description: 'Enable validate tests.')

tests/check/meson.build

@@ -131,15 +131,6 @@ test_deps = [gst_dep, gst_base_dep, gst_net_dep, gst_check_dep, audio_dep,
   video_dep, pbutils_dep, rtp_dep, rtsp_dep, tag_dep, allocators_dep, app_dep,
   fft_dep, riff_dep, sdp_dep, gio_dep, valgrind_dep] + glib_deps
 
-pluginsdirs = []
-if gst_dep.type_name() == 'pkgconfig'
-  pluginsdirs = [gst_dep.get_pkgconfig_variable('pluginsdir')]
-  gst_plugin_scanner_dir = gst_dep.get_pkgconfig_variable('pluginscannerdir')
-else
-  gst_plugin_scanner_dir = gst_proj.get_variable('gst_scanner_dir')
-endif
-gst_plugin_scanner_path = join_paths(gst_plugin_scanner_dir, 'gst-plugin-scanner')
-
 foreach t : base_tests
   fname = t.get(0)
   test_name = fname.split('.').get(0).underscorify()

tests/meson.build

@@ -1,7 +1,20 @@
+pluginsdirs = []
+if gst_dep.type_name() == 'pkgconfig'
+  pluginsdirs = [gst_dep.get_pkgconfig_variable('pluginsdir')]
+  gst_plugin_scanner_dir = gst_dep.get_pkgconfig_variable('pluginscannerdir')
+else
+  gst_plugin_scanner_dir = gst_proj.get_variable('gst_scanner_dir')
+endif
+gst_plugin_scanner_path = join_paths(gst_plugin_scanner_dir, 'gst-plugin-scanner')
+
 if not get_option('tests').disabled() and gst_check_dep.found()
   subdir('check')
   subdir('icles')
 endif
 if not get_option('examples').disabled()
   subdir('examples')
 endif
+
+if not get_option('validate').disabled()
+  subdir('validate')
+endif

tests/validate/audiotestsrc/reverse.validatetest

@@ -0,0 +1,24 @@
+meta,
+    args = {
+        "audiotestsrc name=src samplesperbuffer=1024 ! audio/x-raw,format=S16LE,rate=44100 ! fakesink name=asink sync=true",
+    },
+    configs = {
+        "$(validateflow), pad=asink:sink, record-buffers=true",
+    },
+    handles-states=true,
+    ignore-eos=true
+
+play;
+seek, start=0.0, stop=0.5, rate=-1.0, flags=accurate+flush
+
+crank-clock, expected-time=0.0
+
+# roundup((44100 / 2 / 1024) - 1 (already cranked) + 1 (for eos)) = 22
+crank-clock, repeat=22
+
+set-property, target-element-name="src", property-name="samplesperbuffer", property-value=4410, on-message=eos
+seek, start=0.0, stop=1.0, rate=-1.0, flags=accurate+flush
+crank-clock, expected-elapsed-time=0.0
+crank-clock, repeat=10,  expected-elapsed-time=0.1
+
+stop, on-message=eos;

tests/validate/audiotestsrc/reverse/flow-expectations/log-asink-sink-expected

@@ -0,0 +1,45 @@
+event stream-start: GstEventStreamStart, flags=(GstStreamFlags)GST_STREAM_FLAG_NONE, group-id=(uint)1;
+event caps: audio/x-raw, format=(string)S16LE, layout=(string)interleaved, rate=(int)44100, channels=(int)1;
+event segment: format=TIME, start=0:00:00.000000000, offset=0:00:00.000000000, stop=none, time=0:00:00.000000000, base=0:00:00.000000000, position=0:00:00.000000000
+event tag: GstTagList-stream, taglist=(taglist)"taglist\,\ description\=\(string\)\"audiotest\\\ wave\"\;";
+buffer: pts=0:00:00.000000000, dur=0:00:00.023219954, flags=discont
+event flush-start: (no structure)
+event flush-stop: GstEventFlushStop, reset-time=(boolean)true;
+event segment: format=TIME, start=0:00:00.000000000, offset=0:00:00.000000000, stop=0:00:00.500000000, rate=-1.000000, flags=0x01, time=0:00:00.000000000, base=0:00:00.000000000, position=0:00:00.500000000
+buffer: pts=0:00:00.476780045, dur=0:00:00.023219955, flags=discont
+buffer: pts=0:00:00.453560090, dur=0:00:00.023219955, flags=discont
+buffer: pts=0:00:00.430340136, dur=0:00:00.023219954, flags=discont
+buffer: pts=0:00:00.407120181, dur=0:00:00.023219955, flags=discont
+buffer: pts=0:00:00.383900226, dur=0:00:00.023219955, flags=discont
+buffer: pts=0:00:00.360680272, dur=0:00:00.023219954, flags=discont
+buffer: pts=0:00:00.337460317, dur=0:00:00.023219955, flags=discont
+buffer: pts=0:00:00.314240362, dur=0:00:00.023219955, flags=discont
+buffer: pts=0:00:00.291020408, dur=0:00:00.023219954, flags=discont
+buffer: pts=0:00:00.267800453, dur=0:00:00.023219955, flags=discont
+buffer: pts=0:00:00.244580498, dur=0:00:00.023219955, flags=discont
+buffer: pts=0:00:00.221360544, dur=0:00:00.023219954, flags=discont
+buffer: pts=0:00:00.198140589, dur=0:00:00.023219955, flags=discont
+buffer: pts=0:00:00.174920634, dur=0:00:00.023219955, flags=discont
+buffer: pts=0:00:00.151700680, dur=0:00:00.023219954, flags=discont
+buffer: pts=0:00:00.128480725, dur=0:00:00.023219955, flags=discont
+buffer: pts=0:00:00.105260770, dur=0:00:00.023219955, flags=discont
+buffer: pts=0:00:00.082040816, dur=0:00:00.023219954, flags=discont
+buffer: pts=0:00:00.058820861, dur=0:00:00.023219955, flags=discont
+buffer: pts=0:00:00.035600907, dur=0:00:00.023219954, flags=discont
+buffer: pts=0:00:00.012380952, dur=0:00:00.023219955, flags=discont
+buffer: pts=0:00:00.000000000, dur=0:00:00.012380952, flags=discont
+event eos: (no structure)
+event flush-start: (no structure)
+event flush-stop: GstEventFlushStop, reset-time=(boolean)true;
+event segment: format=TIME, start=0:00:00.000000000, offset=0:00:00.000000000, stop=0:00:01.000000000, rate=-1.000000, flags=0x01, time=0:00:00.000000000, base=0:00:00.000000000, position=0:00:01.000000000
+buffer: pts=0:00:00.900000000, dur=0:00:00.100000000, flags=discont
+buffer: pts=0:00:00.800000000, dur=0:00:00.100000000, flags=discont
+buffer: pts=0:00:00.700000000, dur=0:00:00.100000000, flags=discont
+buffer: pts=0:00:00.600000000, dur=0:00:00.100000000, flags=discont
+buffer: pts=0:00:00.500000000, dur=0:00:00.100000000, flags=discont
+buffer: pts=0:00:00.400000000, dur=0:00:00.100000000, flags=discont
+buffer: pts=0:00:00.300000000, dur=0:00:00.100000000, flags=discont
+buffer: pts=0:00:00.200000000, dur=0:00:00.100000000, flags=discont
+buffer: pts=0:00:00.100000000, dur=0:00:00.100000000, flags=discont
+buffer: pts=0:00:00.000000000, dur=0:00:00.100000000, flags=discont
+event eos: (no structure)

tests/validate/meson.build

@@ -0,0 +1,33 @@
+if gst_dep.type_name() == 'internal'
+    gst_tester = gst_proj.get_variable('gst_tester')
+else
+    gst_tester = find_program('gst-tester-@0@'.format(api_version), required: get_option('validate'))
+    if not gst_tester.found()
+        subdir_done()
+    endif
+endif
+
+tests = [
+    'audiotestsrc/reverse',
+]
+
+env = environment()
+env.set('GST_PLUGIN_PATH_1_0', meson.build_root(), pluginsdirs)
+env.set('GST_PLUGIN_SYSTEM_PATH_1_0', '')
+env.set('GST_REGISTRY', '@0@/@1@.registry'.format(meson.current_build_dir(), 'validate'))
+env.set('GST_PLUGIN_SCANNER_1_0', gst_plugin_scanner_path)
+env.set('GST_PLUGIN_LOADING_WHITELIST', 'gstreamer',
+    'gst-plugins-base@' + meson.build_root())
+
+foreach t: tests
+    test_dir_name = t.split('/')
+    test_name = 'validate'
+    foreach c: test_dir_name
+        test_name += '.' + c
+    endforeach
+    test_env = env
+    test_env.set('GST_VALIDATE_LOGSDIR', join_paths(meson.current_build_dir(), test_name))
+    test_file = join_paths(meson.current_source_dir(), t + '.validatetest')
+    test(test_name, gst_tester, args: [test_file, '--use-fakesinks'],
+        env: test_env, timeout : 3 * 60, protocol: 'tap')
+endforeach