Add default reporter for Bazel integration

When the added Bazel configuration flag is enabled,
a default JUnit reporter will be added if the XML
envrioment variable is defined.
Fix include paths for generated config header.
Enable Bazel config by default when building with
Bazel.

BUILD.bazel

@@ -1,13 +1,13 @@
 # Load the cc_library rule.
 load("@rules_cc//cc:defs.bzl", "cc_library")
-
 load("@bazel_skylib//rules:expand_template.bzl", "expand_template")
 
 expand_template(
-    name = "catch_user_config.hpp",
+    name = "catch_user_config",
     out = "catch2/catch_user_config.hpp",
     substitutions = {
         "#cmakedefine CATCH_CONFIG_ANDROID_LOGWRITE": "",
+        "#cmakedefine CATCH_CONFIG_BAZEL_SUPPORT": " #define CATCH_CONFIG_BAZEL_SUPPORT",
         "#cmakedefine CATCH_CONFIG_COLOUR_ANSI": "",
         "#cmakedefine CATCH_CONFIG_COLOUR_NONE": "",
         "#cmakedefine CATCH_CONFIG_COLOUR_WINDOWS": "",
@@ -57,23 +57,39 @@ expand_template(
     template = "src/catch2/catch_user_config.hpp.in",
 )
 
+# Generated header library, modifies the include prefix to account for
+# generation path so that we can include <catch2/catch_user_config.hpp>
+# correctly.
+cc_library(
+    name = "catch2_generated",
+    hdrs = ["catch2/catch_user_config.hpp"],
+    copts = ["-std=c++14"],
+    include_prefix = ".",  # to manipulate -I of dependenices
+    visibility = ["//visibility:public"],
+)
+
 # Static library, without main.
 cc_library(
     name = "catch2",
-    hdrs = glob(["src/catch2/**/*.hpp"]) + ["catch_user_config.hpp"],
-    srcs = glob(["src/catch2/**/*.cpp"],
-                exclude=[ "src/catch2/internal/catch_main.cpp"]),
-    visibility = ["//visibility:public"],
-    linkstatic = True,
+    srcs = glob(
+        ["src/catch2/**/*.cpp"],
+        exclude = ["src/catch2/internal/catch_main.cpp"],
+    ),
+    hdrs = glob(["src/catch2/**/*.hpp"]),
+    copts = ["-std=c++14"],
     includes = ["src/"],
+    linkstatic = True,
+    visibility = ["//visibility:public"],
+    deps = [":catch2_generated"],
 )
 
 # Static library, with main.
 cc_library(
     name = "catch2_main",
     srcs = ["src/catch2/internal/catch_main.cpp"],
-    deps = [":catch2"],
-    visibility = ["//visibility:public"],
-    linkstatic = True,
+    copts = ["-std=c++14"],
     includes = ["src/"],
+    linkstatic = True,
+    visibility = ["//visibility:public"],
+    deps = [":catch2"],
 )

docs/configuration.md

@@ -97,6 +97,10 @@ This means that defining `CATCH_CONFIG_DEFAULT_REPORTER` to `"console"`
 is equivalent with the out-of-the-box experience.
 
 
+## Bazel support
+When `CATCH_CONFIG_BAZEL_SUPPORT` is defined, Catch2 will register a `JUnit`
+reporter writing to a path pointed by `XML_OUTPUT_FILE` provided by Bazel.
+
 ## C++11 toggles
 
     CATCH_CONFIG_CPP11_TO_STRING // Use `std::to_string`

src/catch2/catch_config.cpp

@@ -8,6 +8,7 @@
 #include <catch2/catch_config.hpp>
 #include <catch2/catch_user_config.hpp>
 #include <catch2/internal/catch_enforce.hpp>
+#include <catch2/internal/catch_platform.hpp>
 #include <catch2/internal/catch_stream.hpp>
 #include <catch2/internal/catch_stringref.hpp>
 #include <catch2/internal/catch_string_manip.hpp>
@@ -80,6 +81,26 @@ namespace Catch {
             } );
         }
 
+#if defined( CATCH_CONFIG_BAZEL_SUPPORT )
+        // Register a JUnit reporter for Bazel. Bazel sets an enviorment
+        // variable with the path to XML output. If this file is written to
+        // during test, Bazel will not generate a default XML output.
+        // This allows the XML output file to contain higher level of detail
+        // than what is possible otherwise.
+#if defined( CATCH_PLATFORM_WINDOWS )
+        // On Windows getenv throws a warning as there is no input validation,
+        // since the key is hardcoded, this should not be an issue.
+#pragma warning(suppress: 4996)
+        auto const bazelOutputFile = std::getenv( "XML_OUTPUT_FILE" );
+#else
+        auto const bazelOutputFile = std::getenv( "XML_OUTPUT_FILE" );
+#endif
+        if ( bazelOutputFile != nullptr ) {
+            m_data.reporterSpecifications.push_back(
+                { "junit", { bazelOutputFile } } );
+        }
+#endif
+
         bool defaultOutputUsed = false;
         m_reporterStreams.reserve( m_data.reporterSpecifications.size() );
         for ( auto const& reporterAndFile : m_data.reporterSpecifications ) {

src/catch2/catch_user_config.hpp.in

@@ -159,6 +159,7 @@
 // ------
 
 
+#cmakedefine CATCH_CONFIG_BAZEL_SUPPORT
 #cmakedefine CATCH_CONFIG_COLOUR_ANSI
 #cmakedefine CATCH_CONFIG_COLOUR_NONE
 #cmakedefine CATCH_CONFIG_COLOUR_WINDOWS

tests/CMakeLists.txt

@@ -473,6 +473,10 @@ set_tests_properties("Reporters::DashAsLocationInReporterSpecSendsOutputToStdout
 )
 
 if (CATCH_ENABLE_CONFIGURE_TESTS)
+    add_test(NAME "CMakeConfig::ConfigureBazelReporter"
+      COMMAND
+        "${PYTHON_EXECUTABLE}" "${CMAKE_CURRENT_LIST_DIR}/TestScripts/testConfigureBazelReporter.py" "${CATCH_DIR}" "${CMAKE_CURRENT_BINARY_DIR}"
+    )
     add_test(NAME "CMakeConfig::DefaultReporter"
       COMMAND
         "${PYTHON_EXECUTABLE}" "${CMAKE_CURRENT_LIST_DIR}/TestScripts/testConfigureDefaultReporter.py" "${CATCH_DIR}" "${CMAKE_CURRENT_BINARY_DIR}"

tests/TestScripts/testConfigureBazelReporter.py

@@ -0,0 +1,90 @@
+#!/usr/bin/env python3
+
+#              Copyright Catch2 Authors
+# Distributed under the Boost Software License, Version 1.0.
+#   (See accompanying file LICENSE_1_0.txt or copy at
+#        https://www.boost.org/LICENSE_1_0.txt)
+
+# SPDX-License-Identifier: BSL-1.0
+
+from ConfigureTestsCommon import configure_and_build, run_and_return_output
+
+import os
+import re
+import sys
+import xml.etree.ElementTree as ET
+
+"""
+Tests the CMake configure option for CATCH_CONFIG_DEFAULT_REPORTER
+
+Requires 2 arguments, path folder where the Catch2's main CMakeLists.txt
+exists, and path to where the output files should be stored.
+"""
+if len(sys.argv) != 3:
+    print("Wrong number of arguments: {}".format(len(sys.argv)))
+    print("Usage: {} catch2-top-level-dir base-build-output-dir".format(sys.argv[0]))
+    exit(1)
+
+catch2_source_path = os.path.abspath(sys.argv[1])
+build_dir_path = os.path.join(
+    os.path.abspath(sys.argv[2]), "CMakeConfigTests", "ConfigureBazelReporter"
+)
+
+configure_and_build(
+    catch2_source_path, build_dir_path, [("CATCH_CONFIG_BAZEL_SUPPORT", "ON")]
+)
+
+xml_out_path = os.path.join(
+    build_dir_path,
+    "test.xml",
+)
+
+# Ensure no file exists from previous test runs
+if os.path.isfile(xml_out_path):
+    os.remove(xml_out_path)
+
+
+os.environ["XML_OUTPUT_FILE"] = xml_out_path
+stdout, _ = run_and_return_output(
+    os.path.join(build_dir_path, "tests"),
+    "SelfTest",
+    ["-s", "[approx][custom]"],
+)
+
+try:
+    tree = ET.parse(xml_out_path)
+except ET.ParseError as ex:
+    print("Invalid XML: '{}'".format(ex))
+    raise
+except FileNotFoundError as ex:
+    print("Could not find '{}'".format(xml_out_path))
+    raise
+
+testcases = tree.findall(".//testcase")
+if len(testcases) != 1:
+    print(
+        "Unexpected number of testcases '{}' in '{}'".format(
+            len(testcases), xml_out_path
+        )
+    )
+    exit(2)
+
+expected = {
+    "classname": "SelfTest.global",
+    "name": "Use a custom approx",
+    "status": "run",
+}
+testcase = testcases[0]
+
+actual = testcase.attrib
+for expect_key, expect_val in expected.items():
+    if expect_key not in actual:
+        print("Key not found in testcase tags: '{}'".format(expect_key))
+        exit(2)
+    if expect_val != actual[expect_key]:
+        print(
+            "Value mismatch in testcase tags '{}' != '{}' for key '{}'".format(
+                expect_val, actual[expect_key], expect_key
+            )
+        )
+        exit(2)