Exit with non-0 return code if no tests were run

A new flag, `--allow-running-no-tests` was added to override this
behaviour if exit code of 0 was desired.

This change also made `-w NoTests` obsolete, and so it has been
removed.

src/catch2/catch_config.cpp

@@ -67,8 +67,10 @@ namespace Catch {
     std::ostream& Config::stream() const               { return m_stream->stream(); }
     StringRef Config::name() const                     { return m_data.name.empty() ? m_data.processName : m_data.name; }
     bool Config::includeSuccessfulResults() const      { return m_data.showSuccessfulTests; }
-    bool Config::warnAboutMissingAssertions() const    { return !!(m_data.warnings & WarnAbout::NoAssertions); }
-    bool Config::warnAboutNoTests() const              { return !!(m_data.warnings & WarnAbout::NoTests); }
+    bool Config::warnAboutMissingAssertions() const {
+        return !!( m_data.warnings & WarnAbout::NoAssertions );
+    }
+    bool Config::zeroTestsCountAsSuccess() const       { return m_data.allowZeroTests; }
     ShowDurations Config::showDurations() const        { return m_data.showDurations; }
     double Config::minDuration() const                 { return m_data.minDuration; }
     TestRunOrder Config::runOrder() const              { return m_data.runOrder; }

src/catch2/catch_config.hpp

@@ -33,6 +33,7 @@ namespace Catch {
         bool showInvisibles = false;
         bool filenamesAsTags = false;
         bool libIdentify = false;
+        bool allowZeroTests = false;
 
         int abortAfter = -1;
         uint32_t rngSeed = generateRandomSeed(GenerateFrom::Default);
@@ -97,7 +98,7 @@ namespace Catch {
         StringRef name() const override;
         bool includeSuccessfulResults() const override;
         bool warnAboutMissingAssertions() const override;
-        bool warnAboutNoTests() const override;
+        bool zeroTestsCountAsSuccess() const override;
         ShowDurations showDurations() const override;
         double minDuration() const override;
         TestRunOrder runOrder() const override;

src/catch2/catch_session.cpp

@@ -105,12 +105,10 @@ namespace Catch {
             }
 
         private:
-            using Tests = std::set<TestCaseHandle const*>;
-
             IStreamingReporter* m_reporter;
             Config const* m_config;
             RunContext m_context;
-            Tests m_tests;
+            std::set<TestCaseHandle const*> m_tests;
             TestSpec::Matches m_matches;
         };
 
@@ -303,8 +301,10 @@ namespace Catch {
             TestGroup tests { CATCH_MOVE(reporter), m_config.get() };
             auto const totals = tests.execute();
 
-            if( m_config->warnAboutNoTests() && totals.error == -1 )
+            if ( totals.testCases.total() == 0
+                && !m_config->zeroTestsCountAsSuccess() ) {
                 return 2;
+            }
 
             // Note that on unices only the lower 8 bits are usually used, clamping
             // the return value to 255 prevents false negative when some multiple

src/catch2/interfaces/catch_interfaces_config.hpp

@@ -27,7 +27,6 @@ namespace Catch {
     struct WarnAbout { enum What {
         Nothing = 0x00,
         NoAssertions = 0x01,
-        NoTests = 0x02
     }; };
 
     enum class ShowDurations {
@@ -64,7 +63,7 @@ namespace Catch {
         virtual bool includeSuccessfulResults() const = 0;
         virtual bool shouldDebugBreak() const = 0;
         virtual bool warnAboutMissingAssertions() const = 0;
-        virtual bool warnAboutNoTests() const = 0;
+        virtual bool zeroTestsCountAsSuccess() const = 0;
         virtual int abortAfter() const = 0;
         virtual bool showInvisibles() const = 0;
         virtual ShowDurations showDurations() const = 0;

src/catch2/internal/catch_commandline.cpp

@@ -24,21 +24,14 @@ namespace Catch {
         using namespace Clara;
 
         auto const setWarning = [&]( std::string const& warning ) {
-                auto warningSet = [&]() {
-                    if( warning == "NoAssertions" )
-                        return WarnAbout::NoAssertions;
-
-                    if ( warning == "NoTests" )
-                        return WarnAbout::NoTests;
-
-                    return WarnAbout::Nothing;
-                }();
-
-                if (warningSet == WarnAbout::Nothing)
-                    return ParserResult::runtimeError( "Unrecognised warning: '" + warning + '\'' );
-                config.warnings = static_cast<WarnAbout::What>( config.warnings | warningSet );
+            if ( warning == "NoAssertions" ) {
+                config.warnings = WarnAbout::NoAssertions;
                 return ParserResult::ok( ParseResultType::Matched );
-            };
+            }
+
+            return ParserResult ::runtimeError(
+                "Unrecognised warning option: '" + warning + '\'' );
+        };
         auto const loadTestNamesFromFile = [&]( std::string const& filename ) {
                 std::ifstream f( filename.c_str() );
                 if( !f.is_open() )
@@ -280,7 +273,10 @@ namespace Catch {
                 ( "split the tests to execute into this many groups" )
             | Opt( setShardIndex, "shard index" )
                 ["--shard-index"]
-                ( "index of the group of tests to execute (see --shard-count)" )
+                ( "index of the group of tests to execute (see --shard-count)" ) |
+            Opt( config.allowZeroTests )
+                ["--allow-running-no-tests"]
+                ( "Treat 'No tests run' as a success" )
             | Arg( config.testsOrTags, "test name|pattern|tags" )
                 ( "which test or tests to use" );