libgimp: new unit testing framework for libgimp.

With Python binding, it gets very easy to test new functions. I've been
wondering if we need C counterparts, but really since it's a GObject
Introspection binding, if a function succeeds there, it should also succeed in C
code.

For now, I'm testing a few of GimpPalette API. Not all of it yet. Also I test
both the direct C binding and PDB procedure since in some cases, one or the
other may not properly working. See #10885.

libgimp/tests/libgimp-run-python-test.sh

@@ -0,0 +1,27 @@
+#!/bin/sh
+
+GIMP_EXE=$1
+TEST_FILE=$2
+SRC_DIR=`dirname $TEST_FILE`
+SRC_DIR=`realpath $SRC_DIR`
+
+if [ ! -f "$TEST_FILE" ]; then
+  echo "ERROR: file '$TEST_FILE' does not exist!"
+  return 1;
+fi
+
+first_char=`head -c1 "$TEST_FILE"`
+
+if [ $first_char != '#' ]; then
+  # Note: I don't actually care that it's a shebang, just that it's a comment,
+  # hence a useless line, because I'm going to remove it and replace it with
+  # gimp_assert() import line.
+  # This will make much easier to debug tests with meaningful line numbers.
+  echo "ERROR: file '$TEST_FILE' should start with a shebang: #!/usr/bin/env python3"
+  return 1;
+fi
+
+header="import os; import sys; sys.path.insert(0, '$SRC_DIR'); from pygimp.utils import gimp_assert;"
+header="$header import pygimp.utils; pygimp.utils.gimp_test_filename = '$TEST_FILE'"
+
+(echo "$header" && tail -n +2 "$TEST_FILE") | "$GIMP_EXE" -nis --batch-interpreter "python-fu-eval" -b - --quit

libgimp/tests/meson.build

@@ -0,0 +1,46 @@
+# XXX: we have a bunch of (manually run?) tests inside libgimp/test/.
+# These should either be deleted or transformed into real unit tests.
+
+tests = [
+  'palette',
+]
+
+# make GIMP runnable without being installed.
+env=environment()
+
+menu_paths=meson.project_build_root() / 'menus:' + meson.project_source_root() / 'menus'
+env.set('GIMP_TESTING_MENUS_PATH', menu_paths)
+
+env.set('GIMP_TESTING_PLUGINDIRS', meson.project_build_root() / 'plug-ins:')
+env.append('GIMP_TESTING_PLUGINDIRS', meson.project_build_root() / 'plug-ins/python')
+env.append('GIMP_TESTING_PLUGINDIRS', meson.project_build_root() / 'plug-ins/common/test-plug-ins/')
+
+env.prepend('GI_TYPELIB_PATH', meson.project_build_root() / 'libgimp')
+env.prepend('LD_LIBRARY_PATH', meson.project_build_root() / 'libgimp')
+env.prepend('LD_LIBRARY_PATH', meson.project_build_root() / 'libgimpbase')
+env.prepend('LD_LIBRARY_PATH', meson.project_build_root() / 'libgimpcolor')
+env.prepend('LD_LIBRARY_PATH', meson.project_build_root() / 'libgimpconfig')
+env.prepend('LD_LIBRARY_PATH', meson.project_build_root() / 'libgimpmath')
+env.prepend('LD_LIBRARY_PATH', meson.project_build_root() / 'libgimpmodule')
+env.prepend('LD_LIBRARY_PATH', meson.project_build_root() / 'libgimpthumb')
+env.prepend('LD_LIBRARY_PATH', meson.project_build_root() / 'libgimpwidgets')
+
+env.set('GIMP_TESTING_ABS_TOP_SRCDIR', meson.project_source_root())
+
+if enable_console_bin
+  gimp_exe=gimpconsole_exe
+else
+  gimp_exe=gimpmain_exe
+endif
+
+run_python_test = find_program('./libgimp-run-python-test.sh')
+foreach test_name : tests
+  basename = 'test-' + test_name
+  py_test  = meson.current_source_dir() / basename + '.py'
+
+  test(test_name, run_python_test,
+       args: [ gimp_exe, py_test ],
+       env: env,
+       suite: ['libgimp', 'python3'],
+       timeout: 60)
+endforeach

libgimp/tests/pygimp/utils.py

@@ -0,0 +1,21 @@
+#!/usr/bin/env python3
+
+import inspect
+import sys
+
+gimp_test_filename = ''
+
+def gimp_assert(subtest_name, test):
+  '''
+  Please call me like this, for instance, if I were testing if gimp_image_new()
+  succeeded:
+    gimp_assert("gimp_image_new()", image is not None)
+  '''
+  if not test:
+    frames = inspect.getouterframes(inspect.currentframe())
+    sys.stderr.write("\n**** START FAILED SUBTEST *****\n")
+    sys.stderr.write("ERROR: {} - line {}: {}\n".format(gimp_test_filename,
+                                                        frames[1].lineno,
+                                                        subtest_name))
+    sys.stderr.write("***** END FAILED SUBTEST ******\n\n")
+  assert test

libgimp/tests/test-palette.py

@@ -0,0 +1,55 @@
+#!/usr/bin/env python3
+
+pal = Gimp.Palette.get_by_name('Bears')
+gimp_assert('gimp_palette_get_by_name()', type(pal) == Gimp.Palette)
+
+pal2 = Gimp.Palette.get_by_name('Bears')
+gimp_assert('gimp_palette_get_by_name() is unique', pal == pal2)
+
+colors = pal.get_colors()
+gimp_assert('gimp_palette_get_colors()', len(colors) == 256 and type(colors[0]) == Gegl.Color)
+
+n_colors = pal.get_color_count()
+gimp_assert('gimp_palette_get_color_count()', len(colors) == n_colors)
+
+# Run the same tests through PDB:
+
+proc   = Gimp.get_pdb().lookup_procedure('gimp-palette-get-by-name')
+config = proc.create_config()
+config.set_property('name', 'Bears')
+result = proc.run(config)
+status = result.index(0)
+gimp_assert('gimp-palette-get-by-name', status == Gimp.PDBStatusType.SUCCESS)
+
+pal2 = result.index(1)
+gimp_assert('gimp-palette-get-by-name and gimp_palette_get_by_name() get identical result', pal == pal2)
+
+proc   = Gimp.get_pdb().lookup_procedure('gimp-palette-get-colors')
+config = proc.create_config()
+config.set_property('palette', pal)
+result = proc.run(config)
+status = result.index(0)
+gimp_assert('gimp-palette-get-colors', status == Gimp.PDBStatusType.SUCCESS)
+
+colors = result.index(1)
+# XXX This test is actually what happens right now, but not what should happen.
+# See: https://gitlab.gnome.org/GNOME/gimp/-/issues/10885#note_2030308
+# And: https://gitlab.gnome.org/GNOME/gobject-introspection/-/issues/492
+# If some day this test fails, and in particular if it can return a list of
+# GeglColor, then we should remove the test and deprecate
+# gimp_value_array_get_color_array() in favor of the generic
+# gimp_value_array_index().
+gimp_assert('gimp-palette-get-colors', type(colors) == GObject.GBoxed)
+
+colors = result.get_color_array(1)
+gimp_assert('gimp_palette_get_colors()', type(colors) == list and len(colors) == 256 and type(colors[0]) == Gegl.Color)
+
+proc   = Gimp.get_pdb().lookup_procedure('gimp-palette-get-color-count')
+config = proc.create_config()
+config.set_property('palette', pal)
+result = proc.run(config)
+status = result.index(0)
+gimp_assert('gimp-palette-get-color-count', status == Gimp.PDBStatusType.SUCCESS)
+
+n_colors = result.index(1)
+gimp_assert('gimp_palette_get_color_count()', len(colors) == n_colors)

libgimpconfig/gimpconfig-path.c

@@ -213,10 +213,17 @@ static gchar        * gimp_config_path_unexpand_only (const gchar  *path) G_GNUC
 gchar *
 gimp_config_build_data_path (const gchar *name)
 {
-  return g_strconcat ("${gimp_dir}", G_DIR_SEPARATOR_S, name,
-                      G_SEARCHPATH_SEPARATOR_S,
-                      "${gimp_data_dir}", G_DIR_SEPARATOR_S, name,
-                      NULL);
+  if (g_getenv ("GIMP_TESTING_ABS_TOP_SRCDIR"))
+    /* Unit-testing mode: the source directory is where data is found. */
+    return g_strconcat (g_getenv ("GIMP_TESTING_ABS_TOP_SRCDIR"),
+                        G_DIR_SEPARATOR_S, "data",
+                        G_DIR_SEPARATOR_S, name,
+                        NULL);
+  else
+    return g_strconcat ("${gimp_dir}", G_DIR_SEPARATOR_S, name,
+                        G_SEARCHPATH_SEPARATOR_S,
+                        "${gimp_data_dir}", G_DIR_SEPARATOR_S, name,
+                        NULL);
 }
 
 /**

meson.build

@@ -1840,6 +1840,9 @@ subdir('plug-ins')
 subdir('app')
 subdir('app-tools')
 
+# Unit testing
+subdir('libgimp/tests')
+
 # Docs
 subdir('docs')
 subdir('devel-docs')