Bug 1611515 - Add test cases for CompileDB command output. r=rstewart

Also this patch adds tests for `ClangdBackend` and `StaticAnalysisBackend` since
both of them are derived from `CompileDB`.

Differential Revision: https://phabricator.services.mozilla.com/D91768

python/mozbuild/mozbuild/test/backend/common.py

@@ -42,6 +42,15 @@ CONFIGS = defaultdict(lambda: {
             'COMPILE_ENVIRONMENT': '1',
         },
     },
+    'database': {
+        'defines': {},
+        'substs': {
+            'CC': 'clang',
+            'CXX': 'clang++',
+            'LIB_PREFIX': 'lib',
+            'LIB_SUFFIX': 'a',
+        },
+    },
     'rust-library': {
         'defines': {},
         'substs': {

python/mozbuild/mozbuild/test/backend/data/database/moz.build

@@ -0,0 +1,12 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# Any copyright is dedicated to the Public Domain.
+# http://creativecommons.org/publicdomain/zero/1.0/
+
+@template
+def Library(name):
+    '''Template for libraries.'''
+    LIBRARY_NAME = name
+
+Library('dummy')
+
+SOURCES = ['bar.c', 'bar.cpp', 'foo.c', 'foo.cpp']

python/mozbuild/mozbuild/test/backend/test_database.py

@@ -0,0 +1,84 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from __future__ import absolute_import, print_function, unicode_literals
+
+import json
+import os
+import six
+
+from mozbuild.compilation.database import CompileDBBackend
+from mozbuild.backend.clangd import ClangdBackend
+from mozbuild.backend.static_analysis import StaticAnalysisBackend
+
+from mozbuild.test.backend.common import BackendTester
+
+from mozunit import main
+
+
+class TestCompileDBBackends(BackendTester):
+    def perform_check(self, compile_commands_path, topsrcdir, topobjdir):
+        self.assertTrue(os.path.exists(compile_commands_path))
+        compile_db = json.loads(open(compile_commands_path, "r").read())
+
+        # Verify that we have the same number of items
+        self.assertEqual(len(compile_db), 4)
+
+        expected_db = [
+            {
+                "directory": topobjdir,
+                "command": "clang -o /dev/null -c -ferror-limit=0 {}/bar.c".format(topsrcdir),
+                "file": "{}/bar.c".format(topsrcdir),
+            },
+            {
+                "directory": topobjdir,
+                "command": "clang -o /dev/null -c -ferror-limit=0 {}/foo.c".format(topsrcdir),
+                "file": "{}/foo.c".format(topsrcdir),
+            },
+            {
+                "directory": topobjdir,
+                "command": "clang++ -o /dev/null -c -ferror-limit=0 {}/bar.cpp".format(topsrcdir),
+                "file": "{}/bar.cpp".format(topsrcdir),
+            },
+            {
+                "directory": topobjdir,
+                "command": "clang++ -o /dev/null -c -ferror-limit=0 {}/foo.cpp".format(topsrcdir),
+                "file": "{}/foo.cpp".format(topsrcdir),
+            },
+        ]
+
+        # Verify item consistency against `expected_db`
+        six.assertCountEqual(self, compile_db, expected_db)
+
+    def test_database(self):
+        """Ensure we can generate a `compile_commands.json` and that is correct."""
+
+        env = self._consume("database", CompileDBBackend)
+        compile_commands_path = os.path.join(env.topobjdir, "compile_commands.json")
+
+        self.perform_check(compile_commands_path, env.topsrcdir, env.topobjdir)
+
+    def test_clangd(self):
+        """Ensure we can generate a `compile_commands.json` and that is correct.
+        in order to be used by ClandBackend"""
+
+        env = self._consume("database", ClangdBackend)
+        compile_commands_path = os.path.join(env.topobjdir, "clangd", "compile_commands.json")
+
+        self.perform_check(compile_commands_path, env.topsrcdir, env.topobjdir)
+
+    def test_static_analysis(self):
+        """Ensure we can generate a `compile_commands.json` and that is correct.
+        in order to be used by StaticAnalysisBackend"""
+
+        env = self._consume("database", StaticAnalysisBackend)
+        compile_commands_path = os.path.join(
+            env.topobjdir, "static-analysis", "compile_commands.json"
+        )
+
+        self.perform_check(compile_commands_path, env.topsrcdir, env.topobjdir)
+
+
+if __name__ == "__main__":
+    main()

python/mozbuild/mozbuild/test/python.ini

@@ -8,6 +8,8 @@ subsuite = mozbuild
 [backend/test_fastermake.py]
 [backend/test_recursivemake.py]
 [backend/test_build.py]
+[backend/test_database.py]
+skip-if = python == 2
 [backend/test_configenvironment.py]
 [backend/test_gn_processor.py]
 [backend/test_partialconfigenvironment.py]