improve unit testing approach

Unit tests were moved to their own subdirectory.
Fixtures common to many unit tests were moved to test/unit/conftest.py.
A facility to execute scripts in page's global scope was added.
A workaround was employed to present information about errors in injected scripts.
Sample unit tests for regexes in common/patterns.js were added.

4 files changed, 243 insertions, 0 deletions

diff --git a/test/unit/__init__.py b/test/unit/__init__.py
new file mode 100644
index 0000000..2b351bb
--- /dev/null
+++ b/test/unit/__init__.py
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: CC0-1.0
+# Copyright (C) 2021 Wojtek Kosior
diff --git a/test/unit/conftest.py b/test/unit/conftest.py
new file mode 100644
index 0000000..6877b7a
--- /dev/null
+++ b/test/unit/conftest.py
@@ -0,0 +1,109 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+"""
+Common fixtures for Haketilo unit tests
+"""
+
+# This file is part of Haketilo.
+#
+# Copyright (C) 2021 Wojtek Kosior <koszko@koszko.org>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+# I, Wojtek Kosior, thereby promise not to sue for violation of this file's
+# license. Although I request that you do not make use this code in a
+# proprietary program, I am not going to enforce this in court.
+
+import pytest
+
+from ..profiles      import firefox_safe_mode
+from ..server        import do_an_internet
+from ..script_loader import load_script
+
+@pytest.fixture(scope="package")
+def proxy():
+    httpd = do_an_internet()
+    yield httpd
+    httpd.shutdown()
+
+@pytest.fixture(scope="package")
+def driver(proxy):
+    with firefox_safe_mode() as driver:
+        yield driver
+        driver.quit()
+
+script_injecting_script = '''\
+/*
+ * Selenium by default executes scripts in some weird one-time context. We want
+ * separately-loaded scripts to be able to access global variables defined
+ * before, including those declared with `const` or `let`. To achieve that, we
+ * run our scripts by injecting them into the page inside a <script> tag. We use
+ * custom properties of the `window` object to communicate with injected code.
+ */
+
+const script_elem = document.createElement('script');
+script_elem.textContent = arguments[0];
+
+delete window.haketilo_selenium_return_value;
+delete window.haketilo_selenium_exception;
+window.returnval = (val => window.haketilo_selenium_return_value = val);
+window.arguments = arguments[1];
+
+document.body.append(script_elem);
+
+/*
+ * To ease debugging, we want this script to forward signal all exceptions from
+ * the injectee.
+ */
+try {
+    if (window.haketilo_selenium_exception !== false)
+        throw 'Error in injected script! Check your geckodriver.log!';
+} finally {
+    script_elem.remove();
+}
+
+return window.haketilo_selenium_return_value;
+'''
+
+def _execute_in_page_context(driver, script, *args):
+    script = script + '\n;\nwindow.haketilo_selenium_exception = false;'
+    try:
+        return driver.execute_script(script_injecting_script, script, args)
+    except Exception as e:
+        import sys
+        lines = enumerate(script.split('\n'), 1)
+        for err_info in [('Failing script\n',), *lines]:
+            print(*err_info, file=sys.stderr)
+
+        raise e from None
+
+@pytest.fixture(scope="package")
+def execute_in_page(driver):
+    def do_execute(script, *args, **kwargs):
+        if 'page' in kwargs:
+            driver.get(kwargs['page'])
+
+        return _execute_in_page_context(driver, script, args)
+
+    yield do_execute
+
+@pytest.fixture(scope="package")
+def load_into_page(driver):
+    def do_load(path, import_dirs, *args, **kwargs):
+        if 'page' in kwargs:
+            driver.get(kwargs['page'])
+
+        _execute_in_page_context(driver, load_script(path, import_dirs), args)
+
+    yield do_load
diff --git a/test/unit/test_basic.py b/test/unit/test_basic.py
new file mode 100644
index 0000000..cbe5c8c
--- /dev/null
+++ b/test/unit/test_basic.py
@@ -0,0 +1,41 @@
+# SPDX-License-Identifier: CC0-1.0
+
+"""
+Haketilo unit tests - base
+"""
+
+# This file is part of Haketilo
+#
+# Copyright (C) 2021, Wojtek Kosior
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the CC0 1.0 Universal License as published by
+# the Creative Commons Corporation.
+#
+# This program 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
+# CC0 1.0 Universal License for more details.
+
+import pytest
+
+def test_driver(driver):
+    """
+    A trivial test case that verifies mocked web pages served by proxy can be
+    accessed by the browser driven.
+    """
+    for proto in ['http://', 'https://']:
+        driver.get(proto + 'gotmyowndoma.in')
+        element = driver.find_element_by_tag_name('title')
+        title = driver.execute_script('return arguments[0].innerText;', element)
+        assert "Schrodinger's Document" in title
+
+def test_script_loader(execute_in_page, load_into_page):
+    """
+    A trivial test case that verifies Haketilo's .js files can be properly
+    loaded into a test page together with their dependencies.
+    """
+    load_into_page('common/stored_types.js', ['common'],
+                   page='https://gotmyowndoma.in')
+
+    assert execute_in_page('returnval(TYPE_PREFIX.VAR);') == '_'
diff --git a/test/unit/test_patterns.py b/test/unit/test_patterns.py
new file mode 100644
index 0000000..4162fc0
--- /dev/null
+++ b/test/unit/test_patterns.py
@@ -0,0 +1,91 @@
+# SPDX-License-Identifier: CC0-1.0
+
+"""
+Haketilo unit tests - URL patterns
+"""
+
+# This file is part of Haketilo
+#
+# Copyright (C) 2021, Wojtek Kosior
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the CC0 1.0 Universal License as published by
+# the Creative Commons Corporation.
+#
+# This program 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
+# CC0 1.0 Universal License for more details.
+
+import pytest
+
+from ..script_loader import load_script
+
+@pytest.fixture(scope="session")
+def patterns_code():
+    yield load_script('common/patterns.js', ['common'])
+
+def test_regexes(execute_in_page, patterns_code):
+    """
+    patterns.js contains regexes used for URL parsing.
+    Verify they work properly.
+    """
+    execute_in_page(patterns_code, page='https://gotmyowndoma.in')
+
+    valid_url = 'https://example.com/a/b?ver=1.2.3#heading2'
+    valid_url_rest = 'example.com/a/b?ver=1.2.3#heading2'
+
+    # Test matching of URL protocol.
+    match = execute_in_page('returnval(proto_regex.exec(arguments[0]));',
+                            valid_url)
+    assert match
+    assert match[1] == 'https'
+    assert match[2] == valid_url_rest
+
+    match = execute_in_page('returnval(proto_regex.exec(arguments[0]));',
+                            '://bad-url.missing/protocol')
+    assert match is None
+
+    # Test matching of http(s) URLs.
+    match = execute_in_page('returnval(http_regex.exec(arguments[0]));',
+                            valid_url_rest)
+    assert match
+    assert match[1] == 'example.com'
+    assert match[2] == '/a/b'
+    assert match[3] == '?ver=1.2.3'
+
+    match = execute_in_page('returnval(http_regex.exec(arguments[0]));',
+                            'another.example.com')
+    assert match
+    assert match[1] == 'another.example.com'
+    assert match[2] == ''
+    assert match[3] == ''
+
+    match = execute_in_page('returnval(http_regex.exec(arguments[0]));',
+                            '/bad/http/example')
+    assert match == None
+
+    # Test matching of file URLs.
+    match = execute_in_page('returnval(file_regex.exec(arguments[0]));',
+                            '/good/file/example')
+    assert match
+    assert match[1] == '/good/file/example'
+
+    # Test matching of ftp URLs.
+    match = execute_in_page('returnval(ftp_regex.exec(arguments[0]));',
+                            'example.com/a/b#heading2')
+    assert match
+    assert match[1] is None
+    assert match[2] == 'example.com'
+    assert match[3] == '/a/b'
+
+    match = execute_in_page('returnval(ftp_regex.exec(arguments[0]));',
+                            'some_user@localhost')
+    assert match
+    assert match[1] == 'some_user@'
+    assert match[2] == 'localhost'
+    assert match[3] == ''
+
+    match = execute_in_page('returnval(ftp_regex.exec(arguments[0]));',
+                            '@bad.url/')
+    assert match is None