Add option to skip forward to the generator interface

docs/event-listeners.md

@@ -10,7 +10,7 @@ in-memory logs if they are not needed (the test case passed).
 Unlike reporters, each registered event listener is always active. Event
 listeners are always notified before reporter(s).
 
-To write your own event listener, you should derive from `Catch::EventListenerBase`,
+To write your own event listener, you should derive from `Catch::TestEventListenerBase`,
 as it provides empty stubs for all reporter events, allowing you to
 only override events you care for. Afterwards you have to register it
 with Catch2 using `CATCH_REGISTER_LISTENER` macro, so that Catch2 knows

docs/generators.md

@@ -252,9 +252,23 @@ struct IGenerator : GeneratorUntypedBase {
     // Returns user-friendly string showing the current generator element
     // Does not have to be overridden, IGenerator provides default implementation
     virtual std::string stringifyImpl() const;
+
+    /**
+     * Customization point for `skipToNthElement`
+     *
+     * Does not have to be overridden, there is a default implementation.
+     * Can be overridden for better performance.
+     *
+     * If there are not enough elements, shall throw an error.
+     *
+     * Going backwards is not supported.
+     */
+    virtual void skipToNthElementImpl( std::size_t n );
 };
 ```
 
+> `skipToNthElementImpl` was added in Catch2 vX.Y.Z
+
 However, to be able to use your custom generator inside `GENERATE`, it
 will need to be wrapped inside a `GeneratorWrapper<T>`.
 `GeneratorWrapper<T>` is a value wrapper around a
@@ -275,7 +289,7 @@ There are two ways to handle this, depending on whether you want this
 to be an error or not.
 
  * If empty generator **is** an error, throw an exception in constructor.
- * If empty generator **is not** an error, use the [`SKIP` macro](skipping-passing-failing.md#skipping-test-cases-at-runtime) in constructor.
+ * If empty generator **is not** an error, use the [`SKIP`](skipping-passing-failing.md#skipping-test-cases-at-runtime) in constructor.
 
 
 

docs/skipping-passing-failing.md

@@ -87,7 +87,7 @@ TEST_CASE("complex test case") {
 ```
 
 This test case will report 5 passing assertions; one for each of the three
-values in section `a1`, and then two in section `a2`, from values 2 and 6.
+values in section `a1`, and then two in section `a2`, from values 2 and 4.
 
 Note that as soon as one section is skipped, the entire test case will
 be reported as _skipped_ (unless there is a failing assertion, in which

examples/300-Gen-OwnGenerator.cpp

@@ -39,6 +39,22 @@ public:
         current_number = m_dist(m_rand);
         return true;
     }
+
+    // Note: this improves the performance only a bit, but it is here
+    //       to show how you can override the skip functionality.
+    void skipToNthElementImpl( std::size_t n ) override {
+        auto current_index = currentElementIndex();
+        assert(current_index <= n);
+        // We cannot jump forward the underlying generator directly,
+        // because we do not know how many bits each distributed number
+        // would consume to be generated.
+        for (; current_index < n; ++current_index) {
+            (void)m_dist(m_rand);
+        }
+
+        // We do not have to touch the current element index; it is handled
+        // by the base class.
+    }
 };
 
 // Avoids -Wweak-vtables

src/catch2/interfaces/catch_interfaces_generatortracker.cpp

@@ -7,6 +7,8 @@
 // SPDX-License-Identifier: BSL-1.0
 
 #include <catch2/interfaces/catch_interfaces_generatortracker.hpp>
+#include <catch2/generators/catch_generators.hpp>
+
 #include <string>
 
 namespace Catch {
@@ -21,6 +23,30 @@ namespace Catch {
             return ret;
         }
 
+        void GeneratorUntypedBase::skipToNthElementImpl( std::size_t n ) {
+            for ( size_t i = m_currentElementIndex; i < n; ++i ) {
+                bool isValid = next();
+                if ( !isValid ) {
+                    Detail::throw_generator_exception(
+                        "Coud not jump to Nth element: not enough elements" );
+                }
+            }
+        }
+
+        void GeneratorUntypedBase::skipToNthElement( std::size_t n ) {
+            if ( n < m_currentElementIndex ) {
+                Detail::throw_generator_exception(
+                    "Tried to jump generator backwards" );
+            }
+            skipToNthElementImpl(n);
+
+            // Fixup tracking after moving the generator forward
+            //  * Ensure that the correct element index is set after skipping
+            //  * Invalidate cache
+            m_currentElementIndex = n;
+            m_stringReprCache.clear();
+        }
+
         StringRef GeneratorUntypedBase::currentElementAsString() const {
             if ( m_stringReprCache.empty() ) {
                 m_stringReprCache = stringifyImpl();

src/catch2/interfaces/catch_interfaces_generatortracker.hpp

@@ -35,6 +35,15 @@ namespace Catch {
             //! Customization point for `currentElementAsString`
             virtual std::string stringifyImpl() const = 0;
 
+            /**
+             * Customization point for skipping to the n-th element
+             *
+             * Defaults to successively calling `countedNext`. If there
+             * are not enough elements to reach the nth one, will throw
+             * an error.
+             */
+            virtual void skipToNthElementImpl( std::size_t n );
+
         public:
             GeneratorUntypedBase() = default;
             // Generation of copy ops is deprecated (and Clang will complain)
@@ -58,6 +67,13 @@ namespace Catch {
 
             std::size_t currentElementIndex() const { return m_currentElementIndex; }
 
+            /**
+             * Moves the generator forward **to** the n-th element
+             *
+             * Cannot move backwards.
+             */
+            void skipToNthElement( std::size_t n );
+
             /**
              * Returns generator's current element as user-friendly string.
              *

src/catch2/internal/catch_jsonwriter.hpp

@@ -8,7 +8,6 @@
 #ifndef CATCH_JSONWRITER_HPP_INCLUDED
 #define CATCH_JSONWRITER_HPP_INCLUDED
 
-#include <catch2/internal/catch_lifetimebound.hpp>
 #include <catch2/internal/catch_reusable_string_stream.hpp>
 #include <catch2/internal/catch_stringref.hpp>
 
@@ -28,8 +27,8 @@ namespace Catch {
 
     class JsonValueWriter {
     public:
-        JsonValueWriter( std::ostream& os CATCH_ATTR_LIFETIMEBOUND );
-        JsonValueWriter( std::ostream& os CATCH_ATTR_LIFETIMEBOUND, std::uint64_t indent_level );
+        JsonValueWriter( std::ostream& os );
+        JsonValueWriter( std::ostream& os, std::uint64_t indent_level );
 
         JsonObjectWriter writeObject() &&;
         JsonArrayWriter writeArray() &&;
@@ -63,8 +62,8 @@ namespace Catch {
 
     class JsonObjectWriter {
     public:
-        JsonObjectWriter( std::ostream& os CATCH_ATTR_LIFETIMEBOUND );
-        JsonObjectWriter( std::ostream& os CATCH_ATTR_LIFETIMEBOUND, std::uint64_t indent_level );
+        JsonObjectWriter( std::ostream& os );
+        JsonObjectWriter( std::ostream& os, std::uint64_t indent_level );
 
         JsonObjectWriter( JsonObjectWriter&& source ) noexcept;
         JsonObjectWriter& operator=( JsonObjectWriter&& source ) = delete;
@@ -82,8 +81,8 @@ namespace Catch {
 
     class JsonArrayWriter {
     public:
-        JsonArrayWriter( std::ostream& os CATCH_ATTR_LIFETIMEBOUND );
-        JsonArrayWriter( std::ostream& os CATCH_ATTR_LIFETIMEBOUND, std::uint64_t indent_level );
+        JsonArrayWriter( std::ostream& os );
+        JsonArrayWriter( std::ostream& os, std::uint64_t indent_level );
 
         JsonArrayWriter( JsonArrayWriter&& source ) noexcept;
         JsonArrayWriter& operator=( JsonArrayWriter&& source ) = delete;

src/catch2/internal/catch_xmlwriter.hpp

@@ -8,7 +8,6 @@
 #ifndef CATCH_XMLWRITER_HPP_INCLUDED
 #define CATCH_XMLWRITER_HPP_INCLUDED
 
-#include <catch2/internal/catch_lifetimebound.hpp>
 #include <catch2/internal/catch_reusable_string_stream.hpp>
 #include <catch2/internal/catch_stringref.hpp>
 
@@ -44,7 +43,7 @@ namespace Catch {
     public:
         enum ForWhat { ForTextNodes, ForAttributes };
 
-        constexpr XmlEncode( StringRef str CATCH_ATTR_LIFETIMEBOUND, ForWhat forWhat = ForTextNodes ):
+        constexpr XmlEncode( StringRef str, ForWhat forWhat = ForTextNodes ):
             m_str( str ), m_forWhat( forWhat ) {}
 
 
@@ -62,7 +61,7 @@ namespace Catch {
 
         class ScopedElement {
         public:
-            ScopedElement( XmlWriter* writer CATCH_ATTR_LIFETIMEBOUND, XmlFormatting fmt );
+            ScopedElement( XmlWriter* writer, XmlFormatting fmt );
 
             ScopedElement( ScopedElement&& other ) noexcept;
             ScopedElement& operator=( ScopedElement&& other ) noexcept;
@@ -94,7 +93,7 @@ namespace Catch {
             XmlFormatting m_fmt;
         };
 
-        XmlWriter( std::ostream& os CATCH_ATTR_LIFETIMEBOUND );
+        XmlWriter( std::ostream& os );
         ~XmlWriter();
 
         XmlWriter( XmlWriter const& ) = delete;

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

@@ -168,6 +168,7 @@ Nor would this
 :test-result: PASS GENERATE can combine literals and generators
 :test-result: PASS Generators -- adapters
 :test-result: PASS Generators -- simple
+:test-result: PASS Generators can be skipped forward
 :test-result: PASS Generators internals
 :test-result: PASS Greater-than inequalities with different epsilons
 :test-result: PASS Hashers with different seed produce different hash with same test case

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

@@ -166,6 +166,7 @@
 :test-result: PASS GENERATE can combine literals and generators
 :test-result: PASS Generators -- adapters
 :test-result: PASS Generators -- simple
+:test-result: PASS Generators can be skipped forward
 :test-result: PASS Generators internals
 :test-result: PASS Greater-than inequalities with different epsilons
 :test-result: PASS Hashers with different seed produce different hash with same test case

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

@@ -787,6 +787,13 @@ Generators.tests.cpp:<line number>: passed: j < i for: -1 < 3
 Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 1
 Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 2
 Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 3
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 0 for: 0 == 0
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 3 for: 3 == 3
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.get() == 3 for: 3 == 3
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 5 for: 5 == 5
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.get() == 5 for: 5 == 5
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.skipToNthElement( 3 )
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.skipToNthElement( 6 )
 GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 123 for: 123 == 123
 GeneratorsImpl.tests.cpp:<line number>: passed: !(gen.next()) for: !false
 GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 1 for: 1 == 1
@@ -2888,7 +2895,7 @@ InternalBenchmark.tests.cpp:<line number>: passed: med == 18. for: 18.0 == 18.0
 InternalBenchmark.tests.cpp:<line number>: passed: q3 == 23. for: 23.0 == 23.0
 Misc.tests.cpp:<line number>: passed:
 Misc.tests.cpp:<line number>: passed:
-test cases:  435 |  317 passed |  95 failed | 6 skipped | 17 failed as expected
-assertions: 2303 | 2105 passed | 157 failed | 41 failed as expected
+test cases:  436 |  318 passed |  95 failed | 6 skipped | 17 failed as expected
+assertions: 2310 | 2112 passed | 157 failed | 41 failed as expected
 
 

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

@@ -785,6 +785,13 @@ Generators.tests.cpp:<line number>: passed: j < i for: -1 < 3
 Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 1
 Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 2
 Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 3
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 0 for: 0 == 0
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 3 for: 3 == 3
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.get() == 3 for: 3 == 3
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 5 for: 5 == 5
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.get() == 5 for: 5 == 5
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.skipToNthElement( 3 )
+GeneratorsImpl.tests.cpp:<line number>: passed: generator.skipToNthElement( 6 )
 GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 123 for: 123 == 123
 GeneratorsImpl.tests.cpp:<line number>: passed: !(gen.next()) for: !false
 GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 1 for: 1 == 1
@@ -2877,7 +2884,7 @@ InternalBenchmark.tests.cpp:<line number>: passed: med == 18. for: 18.0 == 18.0
 InternalBenchmark.tests.cpp:<line number>: passed: q3 == 23. for: 23.0 == 23.0
 Misc.tests.cpp:<line number>: passed:
 Misc.tests.cpp:<line number>: passed:
-test cases:  435 |  317 passed |  95 failed | 6 skipped | 17 failed as expected
-assertions: 2303 | 2105 passed | 157 failed | 41 failed as expected
+test cases:  436 |  318 passed |  95 failed | 6 skipped | 17 failed as expected
+assertions: 2310 | 2112 passed | 157 failed | 41 failed as expected
 
 

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

@@ -1719,6 +1719,6 @@ due to unexpected exception with message:
   Why would you throw a std::string?
 
 ===============================================================================
-test cases:  435 |  335 passed |  76 failed | 7 skipped | 17 failed as expected
-assertions: 2282 | 2105 passed | 136 failed | 41 failed as expected
+test cases:  436 |  336 passed |  76 failed | 7 skipped | 17 failed as expected
+assertions: 2289 | 2112 passed | 136 failed | 41 failed as expected
 

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

@@ -5831,6 +5831,43 @@ Generators.tests.cpp:<line number>: PASSED:
 with expansion:
   12 > 3
 
+-------------------------------------------------------------------------------
+Generators can be skipped forward
+-------------------------------------------------------------------------------
+GeneratorsImpl.tests.cpp:<line number>
+...............................................................................
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.currentElementIndex() == 0 )
+with expansion:
+  0 == 0
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.currentElementIndex() == 3 )
+with expansion:
+  3 == 3
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.get() == 3 )
+with expansion:
+  3 == 3
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.currentElementIndex() == 5 )
+with expansion:
+  5 == 5
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.get() == 5 )
+with expansion:
+  5 == 5
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_THROWS( generator.skipToNthElement( 3 ) )
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_THROWS( generator.skipToNthElement( 6 ) )
+
 -------------------------------------------------------------------------------
 Generators internals
   Single value
@@ -19295,6 +19332,6 @@ Misc.tests.cpp:<line number>
 Misc.tests.cpp:<line number>: PASSED:
 
 ===============================================================================
-test cases:  435 |  317 passed |  95 failed | 6 skipped | 17 failed as expected
-assertions: 2303 | 2105 passed | 157 failed | 41 failed as expected
+test cases:  436 |  318 passed |  95 failed | 6 skipped | 17 failed as expected
+assertions: 2310 | 2112 passed | 157 failed | 41 failed as expected
 

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

@@ -5829,6 +5829,43 @@ Generators.tests.cpp:<line number>: PASSED:
 with expansion:
   12 > 3
 
+-------------------------------------------------------------------------------
+Generators can be skipped forward
+-------------------------------------------------------------------------------
+GeneratorsImpl.tests.cpp:<line number>
+...............................................................................
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.currentElementIndex() == 0 )
+with expansion:
+  0 == 0
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.currentElementIndex() == 3 )
+with expansion:
+  3 == 3
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.get() == 3 )
+with expansion:
+  3 == 3
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.currentElementIndex() == 5 )
+with expansion:
+  5 == 5
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( generator.get() == 5 )
+with expansion:
+  5 == 5
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_THROWS( generator.skipToNthElement( 3 ) )
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_THROWS( generator.skipToNthElement( 6 ) )
+
 -------------------------------------------------------------------------------
 Generators internals
   Single value
@@ -19284,6 +19321,6 @@ Misc.tests.cpp:<line number>
 Misc.tests.cpp:<line number>: PASSED:
 
 ===============================================================================
-test cases:  435 |  317 passed |  95 failed | 6 skipped | 17 failed as expected
-assertions: 2303 | 2105 passed | 157 failed | 41 failed as expected
+test cases:  436 |  318 passed |  95 failed | 6 skipped | 17 failed as expected
+assertions: 2310 | 2112 passed | 157 failed | 41 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="140" skipped="12" tests="2315" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
+  <testsuite name="<exe-name>" errors="17" failures="140" skipped="12" tests="2322" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
     <properties>
       <property name="random-seed" value="1"/>
       <property name="filters" value="&quot;*&quot; ~[!nonportable] ~[!benchmark] ~[approvals]"/>
@@ -837,6 +837,7 @@ at Message.tests.cpp:<line number>
     <testcase classname="<exe-name>.global" name="Generators -- simple" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators -- simple/one" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators -- simple/two" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="Generators can be skipped forward" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators internals" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators internals/Single value" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators internals/Preset values" time="{duration}" status="run"/>

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

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <testsuites>
-  <testsuite name="<exe-name>" errors="17" failures="140" skipped="12" tests="2315" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
+  <testsuite name="<exe-name>" errors="17" failures="140" skipped="12" tests="2322" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
     <properties>
       <property name="random-seed" value="1"/>
       <property name="filters" value="&quot;*&quot; ~[!nonportable] ~[!benchmark] ~[approvals]"/>
@@ -836,6 +836,7 @@ at Message.tests.cpp:<line number>
     <testcase classname="<exe-name>.global" name="Generators -- simple" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators -- simple/one" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators -- simple/two" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="Generators can be skipped forward" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators internals" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators internals/Single value" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Generators internals/Preset values" time="{duration}" status="run"/>

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

@@ -144,6 +144,7 @@ at AssertionHandler.tests.cpp:<line number>
   </file>
   <file path="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp">
     <testCase name="Filter generator throws exception for empty generator" duration="{duration}"/>
+    <testCase name="Generators can be skipped forward" duration="{duration}"/>
     <testCase name="Generators internals" duration="{duration}"/>
     <testCase name="Generators internals/Single value" duration="{duration}"/>
     <testCase name="Generators internals/Preset values" duration="{duration}"/>

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

@@ -143,6 +143,7 @@ at AssertionHandler.tests.cpp:<line number>
   </file>
   <file path="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp">
     <testCase name="Filter generator throws exception for empty generator" duration="{duration}"/>
+    <testCase name="Generators can be skipped forward" duration="{duration}"/>
     <testCase name="Generators internals" duration="{duration}"/>
     <testCase name="Generators internals/Single value" duration="{duration}"/>
     <testCase name="Generators internals/Preset values" duration="{duration}"/>

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

@@ -1430,6 +1430,20 @@ ok {test-number} - 4u * i > str.size() for: 12 > 1
 ok {test-number} - 4u * i > str.size() for: 12 > 2
 # Generators -- simple
 ok {test-number} - 4u * i > str.size() for: 12 > 3
+# Generators can be skipped forward
+ok {test-number} - generator.currentElementIndex() == 0 for: 0 == 0
+# Generators can be skipped forward
+ok {test-number} - generator.currentElementIndex() == 3 for: 3 == 3
+# Generators can be skipped forward
+ok {test-number} - generator.get() == 3 for: 3 == 3
+# Generators can be skipped forward
+ok {test-number} - generator.currentElementIndex() == 5 for: 5 == 5
+# Generators can be skipped forward
+ok {test-number} - generator.get() == 5 for: 5 == 5
+# Generators can be skipped forward
+ok {test-number} - generator.skipToNthElement( 3 )
+# Generators can be skipped forward
+ok {test-number} - generator.skipToNthElement( 6 )
 # Generators internals
 ok {test-number} - gen.get() == 123 for: 123 == 123
 # Generators internals
@@ -4627,5 +4641,5 @@ ok {test-number} - q3 == 23. for: 23.0 == 23.0
 ok {test-number} -
 # xmlentitycheck
 ok {test-number} -
-1..2315
+1..2322
 

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

@@ -1428,6 +1428,20 @@ ok {test-number} - 4u * i > str.size() for: 12 > 1
 ok {test-number} - 4u * i > str.size() for: 12 > 2
 # Generators -- simple
 ok {test-number} - 4u * i > str.size() for: 12 > 3
+# Generators can be skipped forward
+ok {test-number} - generator.currentElementIndex() == 0 for: 0 == 0
+# Generators can be skipped forward
+ok {test-number} - generator.currentElementIndex() == 3 for: 3 == 3
+# Generators can be skipped forward
+ok {test-number} - generator.get() == 3 for: 3 == 3
+# Generators can be skipped forward
+ok {test-number} - generator.currentElementIndex() == 5 for: 5 == 5
+# Generators can be skipped forward
+ok {test-number} - generator.get() == 5 for: 5 == 5
+# Generators can be skipped forward
+ok {test-number} - generator.skipToNthElement( 3 )
+# Generators can be skipped forward
+ok {test-number} - generator.skipToNthElement( 6 )
 # Generators internals
 ok {test-number} - gen.get() == 123 for: 123 == 123
 # Generators internals
@@ -4616,5 +4630,5 @@ ok {test-number} - q3 == 23. for: 23.0 == 23.0
 ok {test-number} -
 # xmlentitycheck
 ok {test-number} -
-1..2315
+1..2322
 

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

@@ -414,6 +414,8 @@
 ##teamcity[testFinished name='Generators -- adapters' duration="{duration}"]
 ##teamcity[testStarted name='Generators -- simple']
 ##teamcity[testFinished name='Generators -- simple' duration="{duration}"]
+##teamcity[testStarted name='Generators can be skipped forward']
+##teamcity[testFinished name='Generators can be skipped forward' duration="{duration}"]
 ##teamcity[testStarted name='Generators internals']
 ##teamcity[testFinished name='Generators internals' duration="{duration}"]
 ##teamcity[testStarted name='Greater-than inequalities with different epsilons']

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

@@ -414,6 +414,8 @@
 ##teamcity[testFinished name='Generators -- adapters' duration="{duration}"]
 ##teamcity[testStarted name='Generators -- simple']
 ##teamcity[testFinished name='Generators -- simple' duration="{duration}"]
+##teamcity[testStarted name='Generators can be skipped forward']
+##teamcity[testFinished name='Generators can be skipped forward' duration="{duration}"]
 ##teamcity[testStarted name='Generators internals']
 ##teamcity[testFinished name='Generators internals' duration="{duration}"]
 ##teamcity[testStarted name='Greater-than inequalities with different epsilons']

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

@@ -6605,6 +6605,65 @@ Approx( 1.30000000000000004 )
     </Section>
     <OverallResult success="true" skips="0"/>
   </TestCase>
+  <TestCase name="Generators can be skipped forward" tags="[generators]" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.currentElementIndex() == 0
+      </Original>
+      <Expanded>
+        0 == 0
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.currentElementIndex() == 3
+      </Original>
+      <Expanded>
+        3 == 3
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.get() == 3
+      </Original>
+      <Expanded>
+        3 == 3
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.currentElementIndex() == 5
+      </Original>
+      <Expanded>
+        5 == 5
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.get() == 5
+      </Original>
+      <Expanded>
+        5 == 5
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE_THROWS" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.skipToNthElement( 3 )
+      </Original>
+      <Expanded>
+        generator.skipToNthElement( 3 )
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE_THROWS" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.skipToNthElement( 6 )
+      </Original>
+      <Expanded>
+        generator.skipToNthElement( 6 )
+      </Expanded>
+    </Expression>
+    <OverallResult success="true" skips="0"/>
+  </TestCase>
   <TestCase name="Generators internals" tags="[generators][internals]" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
     <Section name="Single value" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
       <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
@@ -22324,6 +22383,6 @@ Approx( -1.95996398454005449 )
     </Section>
     <OverallResult success="true" skips="0"/>
   </TestCase>
-  <OverallResults successes="2105" failures="157" expectedFailures="41" skips="12"/>
-  <OverallResultsCases successes="317" failures="95" expectedFailures="17" skips="6"/>
+  <OverallResults successes="2112" failures="157" expectedFailures="41" skips="12"/>
+  <OverallResultsCases successes="318" failures="95" expectedFailures="17" skips="6"/>
 </Catch2TestRun>

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

@@ -6605,6 +6605,65 @@ Approx( 1.30000000000000004 )
     </Section>
     <OverallResult success="true" skips="0"/>
   </TestCase>
+  <TestCase name="Generators can be skipped forward" tags="[generators]" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.currentElementIndex() == 0
+      </Original>
+      <Expanded>
+        0 == 0
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.currentElementIndex() == 3
+      </Original>
+      <Expanded>
+        3 == 3
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.get() == 3
+      </Original>
+      <Expanded>
+        3 == 3
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.currentElementIndex() == 5
+      </Original>
+      <Expanded>
+        5 == 5
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.get() == 5
+      </Original>
+      <Expanded>
+        5 == 5
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE_THROWS" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.skipToNthElement( 3 )
+      </Original>
+      <Expanded>
+        generator.skipToNthElement( 3 )
+      </Expanded>
+    </Expression>
+    <Expression success="true" type="REQUIRE_THROWS" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Original>
+        generator.skipToNthElement( 6 )
+      </Original>
+      <Expanded>
+        generator.skipToNthElement( 6 )
+      </Expanded>
+    </Expression>
+    <OverallResult success="true" skips="0"/>
+  </TestCase>
   <TestCase name="Generators internals" tags="[generators][internals]" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
     <Section name="Single value" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
       <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
@@ -22323,6 +22382,6 @@ Approx( -1.95996398454005449 )
     </Section>
     <OverallResult success="true" skips="0"/>
   </TestCase>
-  <OverallResults successes="2105" failures="157" expectedFailures="41" skips="12"/>
-  <OverallResultsCases successes="317" failures="95" expectedFailures="17" skips="6"/>
+  <OverallResults successes="2112" failures="157" expectedFailures="41" skips="12"/>
+  <OverallResultsCases successes="318" failures="95" expectedFailures="17" skips="6"/>
 </Catch2TestRun>

tests/SelfTest/IntrospectiveTests/GeneratorsImpl.tests.cpp

@@ -85,7 +85,7 @@ TEST_CASE("Generators internals", "[generators][internals]") {
                 filter([](int) { return false; }, values({ 1, 2, 3 })),
                 Catch::GeneratorException);
         }
-        
+
         // Non-trivial usage
         SECTION("Out-of-line predicates are copied into the generator") {
             auto evilNumber = Catch::Detail::make_unique<int>(2);
@@ -586,3 +586,21 @@ TEST_CASE("from_range(container) supports ADL begin/end and arrays", "[generator
     }
 
 }
+
+TEST_CASE( "Generators can be skipped forward", "[generators]" ) {
+    auto generator = Catch::Generators::FixedValuesGenerator<int>( { 0, 1, 2, 3, 4, 5 } );
+    REQUIRE( generator.currentElementIndex() == 0 );
+
+    generator.skipToNthElement( 3 );
+    REQUIRE( generator.currentElementIndex() == 3 );
+    REQUIRE( generator.get() == 3 );
+
+    generator.skipToNthElement( 5 );
+    REQUIRE( generator.currentElementIndex() == 5 );
+    REQUIRE( generator.get() == 5 );
+
+    // Backwards
+    REQUIRE_THROWS( generator.skipToNthElement( 3 ) );
+    // Past the end
+    REQUIRE_THROWS( generator.skipToNthElement( 6 ) );
+}