Add generateRandomSeed utility to generate randomness seed

src/CMakeLists.txt

@@ -106,6 +106,7 @@ set(INTERNAL_HEADERS
     ${SOURCES_DIR}/internal/catch_polyfills.hpp
     ${SOURCES_DIR}/internal/catch_preprocessor.hpp
     ${SOURCES_DIR}/internal/catch_random_number_generator.hpp
+    ${SOURCES_DIR}/internal/catch_random_seed_generation.hpp
     ${SOURCES_DIR}/catch_reporter_registrars.hpp
     ${SOURCES_DIR}/internal/catch_reporter_registry.hpp
     ${SOURCES_DIR}/internal/catch_result_type.hpp
@@ -175,6 +176,7 @@ set(IMPL_SOURCES
     ${SOURCES_DIR}/catch_registry_hub.cpp
     ${SOURCES_DIR}/internal/catch_combined_tu.cpp
     ${SOURCES_DIR}/internal/catch_random_number_generator.cpp
+    ${SOURCES_DIR}/internal/catch_random_seed_generation.cpp
     ${SOURCES_DIR}/internal/catch_reporter_registry.cpp
     ${SOURCES_DIR}/internal/catch_result_type.cpp
     ${SOURCES_DIR}/internal/catch_run_context.cpp

src/catch2/catch_all.hpp

@@ -80,6 +80,7 @@
 #include <catch2/internal/catch_polyfills.hpp>
 #include <catch2/internal/catch_preprocessor.hpp>
 #include <catch2/internal/catch_random_number_generator.hpp>
+#include <catch2/internal/catch_random_seed_generation.hpp>
 #include <catch2/internal/catch_reporter_registry.hpp>
 #include <catch2/internal/catch_result_type.hpp>
 #include <catch2/internal/catch_run_context.hpp>

src/catch2/internal/catch_random_seed_generation.cpp

@@ -0,0 +1,34 @@
+
+//              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
+
+#include <catch2/internal/catch_random_seed_generation.hpp>
+
+#include <catch2/internal/catch_enforce.hpp>
+
+#include <ctime>
+#include <random>
+
+namespace Catch {
+
+    std::uint32_t generateRandomSeed( GenerateFrom from ) {
+        switch ( from ) {
+        case GenerateFrom::Time:
+            return static_cast<std::uint32_t>( std::time( nullptr ) );
+
+        case GenerateFrom::Default:
+        case GenerateFrom::RandomDevice:
+            // In theory, a platform could have random_device that returns just
+            // 16 bits. That is still some randomness, so we don't care too much
+            return static_cast<std::uint32_t>( std::random_device{}() );
+
+        default:
+            CATCH_ERROR("Unknown generation method");
+        }
+    }
+
+} // end namespace Catch

src/catch2/internal/catch_random_seed_generation.hpp

@@ -0,0 +1,26 @@
+
+//              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
+#ifndef CATCH_RANDOM_SEED_GENERATION_HPP_INCLUDED
+#define CATCH_RANDOM_SEED_GENERATION_HPP_INCLUDED
+
+#include <cstdint>
+
+namespace Catch {
+
+    enum class GenerateFrom {
+        Time,
+        RandomDevice,
+        //! Currently equivalent to RandomDevice, but can change at any point
+        Default
+    };
+
+    std::uint32_t generateRandomSeed(GenerateFrom from);
+
+} // end namespace Catch
+
+#endif // CATCH_RANDOM_SEED_GENERATION_HPP_INCLUDED

tests/SelfTest/Baselines/automake.sw.approved.txt

@@ -183,6 +183,8 @@ Nor would this
 :test-result: PASS Product with differing arities - std::tuple<int, double, float>
 :test-result: PASS Product with differing arities - std::tuple<int, double>
 :test-result: PASS Product with differing arities - std::tuple<int>
+:test-result: PASS Random seed generation accepts known methods
+:test-result: PASS Random seed generation reports unknown methods
 :test-result: PASS Range type with sentinel
 :test-result: FAIL Reconstruction should be based on stringification: #914
 :test-result: FAIL Regex string matcher

tests/SelfTest/Baselines/compact.sw.approved.txt

@@ -1272,6 +1272,10 @@ CmdLine.tests.cpp:<line number>: passed: config.benchmarkWarmupTime == 10 for: 1
 Misc.tests.cpp:<line number>: passed: std::tuple_size<TestType>::value >= 1 for: 3 >= 1
 Misc.tests.cpp:<line number>: passed: std::tuple_size<TestType>::value >= 1 for: 2 >= 1
 Misc.tests.cpp:<line number>: passed: std::tuple_size<TestType>::value >= 1 for: 1 >= 1
+RandomNumberGeneration.tests.cpp:<line number>: passed: Catch::generateRandomSeed(method)
+RandomNumberGeneration.tests.cpp:<line number>: passed: Catch::generateRandomSeed(method)
+RandomNumberGeneration.tests.cpp:<line number>: passed: Catch::generateRandomSeed(method)
+RandomNumberGeneration.tests.cpp:<line number>: passed: Catch::generateRandomSeed(static_cast<Catch::GenerateFrom>(77))
 ToString.tests.cpp:<line number>: passed: Catch::Detail::stringify(UsesSentinel{}) == "{  }" for: "{  }" == "{  }"
 Decomposition.tests.cpp:<line number>: failed: truthy(false) for: Hey, its truthy!
 Matchers.tests.cpp:<line number>: failed: testStringForMatching(), Matches( "this STRING contains 'abc' as a substring" ) for: "this string contains 'abc' as a substring" matches "this STRING contains 'abc' as a substring" case sensitively

tests/SelfTest/Baselines/console.std.approved.txt

@@ -1386,6 +1386,6 @@ due to unexpected exception with message:
   Why would you throw a std::string?
 
 ===============================================================================
-test cases:  369 |  293 passed |  70 failed |  6 failed as expected
-assertions: 2106 | 1954 passed | 129 failed | 23 failed as expected
+test cases:  371 |  295 passed |  70 failed |  6 failed as expected
+assertions: 2110 | 1958 passed | 129 failed | 23 failed as expected
 

tests/SelfTest/Baselines/console.sw.approved.txt

@@ -9383,6 +9383,42 @@ Misc.tests.cpp:<line number>: PASSED:
 with expansion:
   1 >= 1
 
+-------------------------------------------------------------------------------
+Random seed generation accepts known methods
+-------------------------------------------------------------------------------
+RandomNumberGeneration.tests.cpp:<line number>
+...............................................................................
+
+RandomNumberGeneration.tests.cpp:<line number>: PASSED:
+  REQUIRE_NOTHROW( Catch::generateRandomSeed(method) )
+
+-------------------------------------------------------------------------------
+Random seed generation accepts known methods
+-------------------------------------------------------------------------------
+RandomNumberGeneration.tests.cpp:<line number>
+...............................................................................
+
+RandomNumberGeneration.tests.cpp:<line number>: PASSED:
+  REQUIRE_NOTHROW( Catch::generateRandomSeed(method) )
+
+-------------------------------------------------------------------------------
+Random seed generation accepts known methods
+-------------------------------------------------------------------------------
+RandomNumberGeneration.tests.cpp:<line number>
+...............................................................................
+
+RandomNumberGeneration.tests.cpp:<line number>: PASSED:
+  REQUIRE_NOTHROW( Catch::generateRandomSeed(method) )
+
+-------------------------------------------------------------------------------
+Random seed generation reports unknown methods
+-------------------------------------------------------------------------------
+RandomNumberGeneration.tests.cpp:<line number>
+...............................................................................
+
+RandomNumberGeneration.tests.cpp:<line number>: PASSED:
+  REQUIRE_THROWS( Catch::generateRandomSeed(static_cast<Catch::GenerateFrom>(77)) )
+
 -------------------------------------------------------------------------------
 Range type with sentinel
 -------------------------------------------------------------------------------
@@ -16954,6 +16990,6 @@ Misc.tests.cpp:<line number>
 Misc.tests.cpp:<line number>: PASSED:
 
 ===============================================================================
-test cases:  369 |  277 passed |  86 failed |  6 failed as expected
-assertions: 2123 | 1954 passed | 146 failed | 23 failed as expected
+test cases:  371 |  279 passed |  86 failed |  6 failed as expected
+assertions: 2127 | 1958 passed | 146 failed | 23 failed as expected
 

tests/SelfTest/Baselines/junit.sw.approved.txt

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <testsuitesloose text artifact
 >
-  <testsuite name="<exe-name>" errors="17" failures="129" tests="2123" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
+  <testsuite name="<exe-name>" errors="17" failures="129" tests="2127" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
     <properties>
       <property name="filters" value="~[!nonportable]~[!benchmark]~[approvals] *"/>
       <property name="random-seed" value="1"/>
@@ -1066,6 +1066,8 @@ Message.tests.cpp:<line number>
     <testcase classname="<exe-name>.global" name="Product with differing arities - std::tuple&lt;int, double, float>" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Product with differing arities - std::tuple&lt;int, double>" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Product with differing arities - std::tuple&lt;int>" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="Random seed generation accepts known methods" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="Random seed generation reports unknown methods" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Range type with sentinel" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Reconstruction should be based on stringification: #914" time="{duration}" status="run">
       <failure message="truthy(false)" type="CHECK">

tests/SelfTest/Baselines/sonarqube.sw.approved.txt

@@ -152,6 +152,8 @@
     <testCase name="Comparison ops" duration="{duration}"/>
     <testCase name="Our PCG implementation provides expected results for known seeds/Default seeded" duration="{duration}"/>
     <testCase name="Our PCG implementation provides expected results for known seeds/Specific seed" duration="{duration}"/>
+    <testCase name="Random seed generation accepts known methods" duration="{duration}"/>
+    <testCase name="Random seed generation reports unknown methods" duration="{duration}"/>
   </file>
   <file path="tests/<exe-name>/IntrospectiveTests/Reporters.tests.cpp">
     <testCase name="Reporter's write listings to provided stream" duration="{duration}"/>

tests/SelfTest/Baselines/tap.sw.approved.txt

@@ -2466,6 +2466,14 @@ ok {test-number} - std::tuple_size<TestType>::value >= 1 for: 3 >= 1
 ok {test-number} - std::tuple_size<TestType>::value >= 1 for: 2 >= 1
 # Product with differing arities - std::tuple<int>
 ok {test-number} - std::tuple_size<TestType>::value >= 1 for: 1 >= 1
+# Random seed generation accepts known methods
+ok {test-number} - Catch::generateRandomSeed(method)
+# Random seed generation accepts known methods
+ok {test-number} - Catch::generateRandomSeed(method)
+# Random seed generation accepts known methods
+ok {test-number} - Catch::generateRandomSeed(method)
+# Random seed generation reports unknown methods
+ok {test-number} - Catch::generateRandomSeed(static_cast<Catch::GenerateFrom>(77))
 # Range type with sentinel
 ok {test-number} - Catch::Detail::stringify(UsesSentinel{}) == "{  }" for: "{  }" == "{  }"
 # Reconstruction should be based on stringification: #914
@@ -4248,5 +4256,5 @@ ok {test-number} - q3 == 23. for: 23.0 == 23.0
 ok {test-number} -
 # xmlentitycheck
 ok {test-number} -
-1..2123
+1..2127
 

tests/SelfTest/Baselines/teamcity.sw.approved.txt

@@ -467,6 +467,10 @@ Message.tests.cpp:<line number>|nexplicit failure with message:|n  "Message from
 ##teamcity[testFinished name='Product with differing arities - std::tuple<int, double>' duration="{duration}"]
 ##teamcity[testStarted name='Product with differing arities - std::tuple<int>']
 ##teamcity[testFinished name='Product with differing arities - std::tuple<int>' duration="{duration}"]
+##teamcity[testStarted name='Random seed generation accepts known methods']
+##teamcity[testFinished name='Random seed generation accepts known methods' duration="{duration}"]
+##teamcity[testStarted name='Random seed generation reports unknown methods']
+##teamcity[testFinished name='Random seed generation reports unknown methods' duration="{duration}"]
 ##teamcity[testStarted name='Range type with sentinel']
 ##teamcity[testFinished name='Range type with sentinel' duration="{duration}"]
 ##teamcity[testStarted name='Reconstruction should be based on stringification: #914']

tests/SelfTest/Baselines/xml.sw.approved.txt

@@ -11468,6 +11468,44 @@ Nor would this
     </Expression>
     <OverallResult success="true"/>
   </TestCase>
+  <TestCase name="Random seed generation accepts known methods" tags="[rng][seed]" filename="tests/<exe-name>/IntrospectiveTests/RandomNumberGeneration.tests.cpp" >
+    <Expression success="true" type="REQUIRE_NOTHROW" filename="tests/<exe-name>/IntrospectiveTests/RandomNumberGeneration.tests.cpp" >
+      <Original>
+        Catch::generateRandomSeed(method)
+      </Original>
+      <Expanded>
+        Catch::generateRandomSeed(method)
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE_NOTHROW" filename="tests/<exe-name>/IntrospectiveTests/RandomNumberGeneration.tests.cpp" >
+      <Original>
+        Catch::generateRandomSeed(method)
+      </Original>
+      <Expanded>
+        Catch::generateRandomSeed(method)
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE_NOTHROW" filename="tests/<exe-name>/IntrospectiveTests/RandomNumberGeneration.tests.cpp" >
+      <Original>
+        Catch::generateRandomSeed(method)
+      </Original>
+      <Expanded>
+        Catch::generateRandomSeed(method)
+      </Expanded>
+    </Expression>
+    <OverallResult success="true"/>
+  </TestCase>
+  <TestCase name="Random seed generation reports unknown methods" tags="[rng][seed]" filename="tests/<exe-name>/IntrospectiveTests/RandomNumberGeneration.tests.cpp" >
+    <Expression success="true" type="REQUIRE_THROWS" filename="tests/<exe-name>/IntrospectiveTests/RandomNumberGeneration.tests.cpp" >
+      <Original>
+        Catch::generateRandomSeed(static_cast&lt;Catch::GenerateFrom>(77))
+      </Original>
+      <Expanded>
+        Catch::generateRandomSeed(static_cast&lt;Catch::GenerateFrom>(77))
+      </Expanded>
+    </Expression>
+    <OverallResult success="true"/>
+  </TestCase>
   <TestCase name="Range type with sentinel" filename="tests/<exe-name>/IntrospectiveTests/ToString.tests.cpp" >
     <Expression success="true" type="CHECK" filename="tests/<exe-name>/IntrospectiveTests/ToString.tests.cpp" >
       <Original>
@@ -19953,6 +19991,6 @@ loose text artifact
     </Section>
     <OverallResult success="true"/>
   </TestCase>
-  <OverallResults successes="1954" failures="146" expectedFailures="23"/>
-  <OverallResultsCases successes="277" failures="86" expectedFailures="6"/>
+  <OverallResults successes="1958" failures="146" expectedFailures="23"/>
+  <OverallResultsCases successes="279" failures="86" expectedFailures="6"/>
 </Catch2TestRun>

tests/SelfTest/IntrospectiveTests/RandomNumberGeneration.tests.cpp

@@ -5,6 +5,8 @@
 
 #include <catch2/catch_test_macros.hpp>
 #include <catch2/internal/catch_random_number_generator.hpp>
+#include <catch2/internal/catch_random_seed_generation.hpp>
+#include <catch2/generators/catch_generators.hpp>
 
 TEST_CASE("Our PCG implementation provides expected results for known seeds", "[rng]") {
     Catch::SimplePcg32 rng;
@@ -40,3 +42,18 @@ TEST_CASE("Comparison ops", "[rng]") {
     REQUIRE_FALSE(SimplePcg32{ 1 } == SimplePcg32{ 2 });
     REQUIRE_FALSE(SimplePcg32{ 1 } != SimplePcg32{ 1 });
 }
+
+TEST_CASE("Random seed generation reports unknown methods", "[rng][seed]") {
+    REQUIRE_THROWS(Catch::generateRandomSeed(static_cast<Catch::GenerateFrom>(77)));
+}
+
+TEST_CASE("Random seed generation accepts known methods", "[rng][seed]") {
+    using Catch::GenerateFrom;
+    const auto method = GENERATE(
+        GenerateFrom::Time,
+        GenerateFrom::RandomDevice,
+        GenerateFrom::Default
+    );
+
+    REQUIRE_NOTHROW(Catch::generateRandomSeed(method));
+}