oeqa: reproducible: Fix test not producing diffs

Diffoscope changed the --exclude-directory-metadata option to require an
argument.

Add a test to validate that diffoscope is functioning as
expected to ensure that future upgrades do not unintentionally break
the reproducibility tests.

[YOCTO #14025]

(From OE-Core rev: ea8fbcb7978ce48d7a9a83143d09402329535f86)

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/selftest/cases/diffoscope/A/file.txt

@@ -0,0 +1 @@
+A

meta/lib/oeqa/selftest/cases/diffoscope/B/file.txt

@@ -0,0 +1 @@
+B

meta/lib/oeqa/selftest/cases/reproducible.py

@@ -77,6 +77,32 @@ def compare_file(reference, test, diffutils_sysroot):
     result.status = SAME
     return result
 
+def run_diffoscope(a_dir, b_dir, html_dir, **kwargs):
+    return runCmd(['diffoscope', '--no-default-limits', '--exclude-directory-metadata', 'yes', '--html-dir', html_dir, a_dir, b_dir],
+                **kwargs)
+
+class DiffoscopeTests(OESelftestTestCase):
+    diffoscope_test_files = os.path.join(os.path.dirname(os.path.abspath(__file__)), "diffoscope")
+
+    def test_diffoscope(self):
+        bitbake("diffoscope-native -c addto_recipe_sysroot")
+        diffoscope_sysroot = get_bb_var("RECIPE_SYSROOT_NATIVE", "diffoscope-native")
+
+        # Check that diffoscope doesn't return an error when the files compare
+        # the same (a general check that diffoscope is working)
+        with tempfile.TemporaryDirectory() as tmpdir:
+            run_diffoscope('A', 'A', tmpdir,
+                native_sysroot=diffoscope_sysroot, cwd=self.diffoscope_test_files)
+
+        # Check that diffoscope generates an index.html file when the files are
+        # different
+        with tempfile.TemporaryDirectory() as tmpdir:
+            r = run_diffoscope('A', 'B', tmpdir,
+                native_sysroot=diffoscope_sysroot, ignore_status=True, cwd=self.diffoscope_test_files)
+
+            self.assertNotEqual(r.status, 0, msg="diffoscope was successful when an error was expected")
+            self.assertTrue(os.path.exists(os.path.join(tmpdir, 'index.html')), "HTML index not found!")
+
 class ReproducibleTests(OESelftestTestCase):
     package_classes = ['deb', 'ipk']
     images = ['core-image-minimal', 'core-image-sato', 'core-image-full-cmdline']
@@ -232,7 +258,7 @@ class ReproducibleTests(OESelftestTestCase):
                 # Copy jquery to improve the diffoscope output usability
                 self.copy_file(os.path.join(jquery_sysroot, 'usr/share/javascript/jquery/jquery.min.js'), os.path.join(package_html_dir, 'jquery.js'))
 
-                runCmd(['diffoscope', '--no-default-limits', '--exclude-directory-metadata', '--html-dir', package_html_dir, 'reproducibleA', 'reproducibleB'],
+                run_diffoscope('reproducibleA', 'reproducibleB', package_html_dir,
                         native_sysroot=diffoscope_sysroot, ignore_status=True, cwd=package_dir)
 
         if fails: