Split test case collection from checks

Move the test case collection code out of check_test_cases.py and into its
own module. This allows outcome analysis to depend only on the new module
and not on check_test_cases.py.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/scripts/collect_test_cases.py b/tests/scripts/collect_test_cases.py
index 7e9031c..c326710 100644
--- a/tests/scripts/collect_test_cases.py
+++ b/tests/scripts/collect_test_cases.py
@@ -2,3 +2,166 @@
 
 # Copyright The Mbed TLS Contributors
 # SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+
+import glob
+import os
+import re
+import subprocess
+import sys
+
+import scripts_path # pylint: disable=unused-import
+from mbedtls_framework import build_tree
+
+
+class ScriptOutputError(ValueError):
+    """A kind of ValueError that indicates we found
+    the script doesn't list test cases in an expected
+    pattern.
+    """
+
+    @property
+    def script_name(self):
+        return super().args[0]
+
+    @property
+    def idx(self):
+        return super().args[1]
+
+    @property
+    def line(self):
+        return super().args[2]
+
+class Results:
+    """Store file and line information about errors or warnings in test suites."""
+
+    def __init__(self, options):
+        self.errors = 0
+        self.warnings = 0
+        self.ignore_warnings = options.quiet
+
+    def error(self, file_name, line_number, fmt, *args):
+        sys.stderr.write(('{}:{}:ERROR:' + fmt + '\n').
+                         format(file_name, line_number, *args))
+        self.errors += 1
+
+    def warning(self, file_name, line_number, fmt, *args):
+        if not self.ignore_warnings:
+            sys.stderr.write(('{}:{}:Warning:' + fmt + '\n')
+                             .format(file_name, line_number, *args))
+            self.warnings += 1
+
+class TestDescriptionExplorer:
+    """An iterator over test cases with descriptions.
+
+The test cases that have descriptions are:
+* Individual unit tests (entries in a .data file) in test suites.
+* Individual test cases in ssl-opt.sh.
+
+This is an abstract class. To use it, derive a class that implements
+the process_test_case method, and call walk_all().
+"""
+
+    def process_test_case(self, per_file_state,
+                          file_name, line_number, description):
+        """Process a test case.
+
+per_file_state: an object created by new_per_file_state() at the beginning
+                of each file.
+file_name: a relative path to the file containing the test case.
+line_number: the line number in the given file.
+description: the test case description as a byte string.
+"""
+        raise NotImplementedError
+
+    def new_per_file_state(self):
+        """Return a new per-file state object.
+
+The default per-file state object is None. Child classes that require per-file
+state may override this method.
+"""
+        #pylint: disable=no-self-use
+        return None
+
+    def walk_test_suite(self, data_file_name):
+        """Iterate over the test cases in the given unit test data file."""
+        in_paragraph = False
+        descriptions = self.new_per_file_state() # pylint: disable=assignment-from-none
+        with open(data_file_name, 'rb') as data_file:
+            for line_number, line in enumerate(data_file, 1):
+                line = line.rstrip(b'\r\n')
+                if not line:
+                    in_paragraph = False
+                    continue
+                if line.startswith(b'#'):
+                    continue
+                if not in_paragraph:
+                    # This is a test case description line.
+                    self.process_test_case(descriptions,
+                                           data_file_name, line_number, line)
+                in_paragraph = True
+
+    def collect_from_script(self, script_name):
+        """Collect the test cases in a script by calling its listing test cases
+option"""
+        descriptions = self.new_per_file_state() # pylint: disable=assignment-from-none
+        listed = subprocess.check_output(['sh', script_name, '--list-test-cases'])
+        # Assume test file is responsible for printing identical format of
+        # test case description between --list-test-cases and its OUTCOME.CSV
+        #
+        # idx indicates the number of test case since there is no line number
+        # in the script for each test case.
+        for idx, line in enumerate(listed.splitlines()):
+            # We are expecting the script to list the test cases in
+            # `<suite_name>;<description>` pattern.
+            script_outputs = line.split(b';', 1)
+            if len(script_outputs) == 2:
+                suite_name, description = script_outputs
+            else:
+                raise ScriptOutputError(script_name, idx, line.decode("utf-8"))
+
+            self.process_test_case(descriptions,
+                                   suite_name.decode('utf-8'),
+                                   idx,
+                                   description.rstrip())
+
+    @staticmethod
+    def collect_test_directories():
+        """Get the relative path for the TLS and Crypto test directories."""
+        mbedtls_root = build_tree.guess_mbedtls_root()
+        directories = [os.path.join(mbedtls_root, 'tests'),
+                       os.path.join(mbedtls_root, 'tf-psa-crypto', 'tests')]
+        directories = [os.path.relpath(p) for p in directories]
+        return directories
+
+    def walk_all(self):
+        """Iterate over all named test cases."""
+        test_directories = self.collect_test_directories()
+        for directory in test_directories:
+            for data_file_name in glob.glob(os.path.join(directory, 'suites',
+                                                         '*.data')):
+                self.walk_test_suite(data_file_name)
+
+            for sh_file in ['ssl-opt.sh', 'compat.sh']:
+                sh_file = os.path.join(directory, sh_file)
+                if os.path.isfile(sh_file):
+                    self.collect_from_script(sh_file)
+
+class TestDescriptions(TestDescriptionExplorer):
+    """Collect the available test cases."""
+
+    def __init__(self):
+        super().__init__()
+        self.descriptions = set()
+
+    def process_test_case(self, _per_file_state,
+                          file_name, _line_number, description):
+        """Record an available test case."""
+        base_name = re.sub(r'\.[^.]*$', '', re.sub(r'.*/', '', file_name))
+        key = ';'.join([base_name, description.decode('utf-8')])
+        self.descriptions.add(key)
+
+def collect_available_test_cases():
+    """Collect the available test cases."""
+    explorer = TestDescriptions()
+    explorer.walk_all()
+    return sorted(explorer.descriptions)