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Add option to skip forward to the generator interface
1 parent 363ca5a commit fecf606

22 files changed

Lines changed: 353 additions & 19 deletions

‎docs/generators.md‎

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@@ -252,9 +252,23 @@ struct IGenerator : GeneratorUntypedBase {
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// Returns user-friendly string showing the current generator element
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// Does not have to be overridden, IGenerator provides default implementation
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virtual std::string stringifyImpl() const;
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/**
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* Customization point for `skipToNthElement`
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*
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* Does not have to be overridden, there is a default implementation.
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* Can be overridden for better performance.
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*
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* If there are not enough elements, shall throw an error.
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*
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* Going backwards is not supported.
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*/
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virtual void skipToNthElementImpl( std::size_t n );
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};
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```
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> `skipToNthElementImpl` was added in Catch2 vX.Y.Z
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However, to be able to use your custom generator inside `GENERATE`, it
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will need to be wrapped inside a `GeneratorWrapper<T>`.
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`GeneratorWrapper<T>` is a value wrapper around a

‎examples/300-Gen-OwnGenerator.cpp‎

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

‎src/catch2/interfaces/catch_interfaces_generatortracker.cpp‎

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

‎src/catch2/interfaces/catch_interfaces_generatortracker.hpp‎

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

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

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

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

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

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

Lines changed: 9 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -787,6 +787,13 @@ Generators.tests.cpp:<line number>: passed: j < i for: -1 < 3
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Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 1
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Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 2
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Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 3
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GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 0 for: 0 == 0
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GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 3 for: 3 == 3
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GeneratorsImpl.tests.cpp:<line number>: passed: generator.get() == 3 for: 3 == 3
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GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 5 for: 5 == 5
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GeneratorsImpl.tests.cpp:<line number>: passed: generator.get() == 5 for: 5 == 5
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GeneratorsImpl.tests.cpp:<line number>: passed: generator.skipToNthElement( 3 )
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GeneratorsImpl.tests.cpp:<line number>: passed: generator.skipToNthElement( 6 )
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GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 123 for: 123 == 123
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GeneratorsImpl.tests.cpp:<line number>: passed: !(gen.next()) for: !false
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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
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InternalBenchmark.tests.cpp:<line number>: passed: q3 == 23. for: 23.0 == 23.0
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Misc.tests.cpp:<line number>: passed:
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Misc.tests.cpp:<line number>: passed:
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test cases: 435 | 317 passed | 95 failed | 6 skipped | 17 failed as expected
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assertions: 2303 | 2105 passed | 157 failed | 41 failed as expected
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test cases: 436 | 318 passed | 95 failed | 6 skipped | 17 failed as expected
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assertions: 2310 | 2112 passed | 157 failed | 41 failed as expected
28932900

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

Lines changed: 9 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -785,6 +785,13 @@ Generators.tests.cpp:<line number>: passed: j < i for: -1 < 3
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Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 1
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Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 2
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Generators.tests.cpp:<line number>: passed: 4u * i > str.size() for: 12 > 3
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GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 0 for: 0 == 0
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GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 3 for: 3 == 3
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GeneratorsImpl.tests.cpp:<line number>: passed: generator.get() == 3 for: 3 == 3
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GeneratorsImpl.tests.cpp:<line number>: passed: generator.currentElementIndex() == 5 for: 5 == 5
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GeneratorsImpl.tests.cpp:<line number>: passed: generator.get() == 5 for: 5 == 5
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GeneratorsImpl.tests.cpp:<line number>: passed: generator.skipToNthElement( 3 )
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GeneratorsImpl.tests.cpp:<line number>: passed: generator.skipToNthElement( 6 )
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GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 123 for: 123 == 123
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GeneratorsImpl.tests.cpp:<line number>: passed: !(gen.next()) for: !false
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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
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InternalBenchmark.tests.cpp:<line number>: passed: q3 == 23. for: 23.0 == 23.0
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Misc.tests.cpp:<line number>: passed:
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Misc.tests.cpp:<line number>: passed:
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test cases: 435 | 317 passed | 95 failed | 6 skipped | 17 failed as expected
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assertions: 2303 | 2105 passed | 157 failed | 41 failed as expected
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test cases: 436 | 318 passed | 95 failed | 6 skipped | 17 failed as expected
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assertions: 2310 | 2112 passed | 157 failed | 41 failed as expected
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‎tests/SelfTest/Baselines/console.std.approved.txt‎

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

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@@ -5831,6 +5831,43 @@ Generators.tests.cpp:<line number>: PASSED:
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with expansion:
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12 > 3
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-------------------------------------------------------------------------------
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Generators can be skipped forward
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-------------------------------------------------------------------------------
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GeneratorsImpl.tests.cpp:<line number>
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...............................................................................
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GeneratorsImpl.tests.cpp:<line number>: PASSED:
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REQUIRE( generator.currentElementIndex() == 0 )
5842+
with expansion:
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0 == 0
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GeneratorsImpl.tests.cpp:<line number>: PASSED:
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REQUIRE( generator.currentElementIndex() == 3 )
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with expansion:
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3 == 3
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GeneratorsImpl.tests.cpp:<line number>: PASSED:
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REQUIRE( generator.get() == 3 )
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with expansion:
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3 == 3
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GeneratorsImpl.tests.cpp:<line number>: PASSED:
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REQUIRE( generator.currentElementIndex() == 5 )
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with expansion:
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5 == 5
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GeneratorsImpl.tests.cpp:<line number>: PASSED:
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REQUIRE( generator.get() == 5 )
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with expansion:
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5 == 5
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GeneratorsImpl.tests.cpp:<line number>: PASSED:
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REQUIRE_THROWS( generator.skipToNthElement( 3 ) )
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GeneratorsImpl.tests.cpp:<line number>: PASSED:
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REQUIRE_THROWS( generator.skipToNthElement( 6 ) )
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-------------------------------------------------------------------------------
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Generators internals
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Single value
@@ -19295,6 +19332,6 @@ Misc.tests.cpp:<line number>
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Misc.tests.cpp:<line number>: PASSED:
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===============================================================================
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test cases: 435 | 317 passed | 95 failed | 6 skipped | 17 failed as expected
19299-
assertions: 2303 | 2105 passed | 157 failed | 41 failed as expected
19335+
test cases: 436 | 318 passed | 95 failed | 6 skipped | 17 failed as expected
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assertions: 2310 | 2112 passed | 157 failed | 41 failed as expected
1930019337

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