WIP: support bazel random seed env var

src/catch2/catch_config.cpp

@@ -253,6 +253,21 @@ namespace Catch {
         if (bazelExitGuardFile) {
             m_data.prematureExitGuardFilePath = bazelExitGuardFile;
         }
+
+        const auto bazelRandomSeed = Detail::getEnv( "TEST_RANDOM_SEED" );
+        if ( bazelRandomSeed ) {
+            auto parsedSeed = parseUInt( bazelRandomSeed, 0 );
+            if ( !parsedSeed ) {
+                // Currently we handle issues with parsing other Bazel Env
+                // options by warning and ignoring the issue. So we do the
+                // same for random seed option.
+                Catch::cerr()
+                    << "Warning: could not parse 'TEST_RANDOM_SEED' ('"
+                    << bazelRandomSeed << "') as proper seed.\n";
+            } else {
+                m_data.rngSeed = *parsedSeed;
+            }
+        }
     }
 
 } // end namespace Catch

tests/CMakeLists.txt

@@ -662,5 +662,26 @@ foreach(reporterName # "Automake" - the simple .trs format does not support any
   )
 endforeach()
 
+add_test(NAME "Bazel::RngSeedEnvVar"
+  COMMAND
+    $<TARGET_FILE:SelfTest> "Factorials are computed"
+)
+set_tests_properties("Bazel::RngSeedEnvVar"
+  PROPERTIES
+    ENVIRONMENT "BAZEL_TEST=1;TEST_RANDOM_SEED=18181818"
+    PASS_REGULAR_EXPRESSION "Randomness seeded to: 18181818"
+)
+
+add_test(NAME "Bazel::RngSeedEnvVarPriorityOverCLI"
+  COMMAND
+    $<TARGET_FILE:SelfTest> "Factorials are computed"
+    --rng-seed 17171717
+)
+set_tests_properties("Bazel::RngSeedEnvVarPriorityOverCLI"
+  PROPERTIES
+    ENVIRONMENT "BAZEL_TEST=1;TEST_RANDOM_SEED=18181818"
+    PASS_REGULAR_EXPRESSION "Randomness seeded to: 18181818"
+)
+
 list(APPEND CATCH_TEST_TARGETS SelfTest)
 set(CATCH_TEST_TARGETS ${CATCH_TEST_TARGETS} PARENT_SCOPE)