Fix ChunkGenerator with chunk-size 0

Fixes #1671

include/internal/catch_generators_generic.hpp

@@ -205,12 +205,14 @@ namespace Generators {
             m_chunk_size(size), m_generator(std::move(generator))
         {
             m_chunk.reserve(m_chunk_size);
-            m_chunk.push_back(m_generator.get());
+            if (m_chunk_size != 0) {
-            for (size_t i = 1; i < m_chunk_size; ++i) {
-                if (!m_generator.next()) {
-                    Catch::throw_exception(GeneratorException("Not enough values to initialize the first chunk"));
-                }
                 m_chunk.push_back(m_generator.get());
+                for (size_t i = 1; i < m_chunk_size; ++i) {
+                    if (!m_generator.next()) {
+                        Catch::throw_exception(GeneratorException("Not enough values to initialize the first chunk"));
+                    }
+                    m_chunk.push_back(m_generator.get());
+                }
             }
         }
         std::vector<T> const& get() const override {

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

@@ -467,6 +467,9 @@ Generators.tests.cpp:<line number>: passed: chunk2.front() < 3 for: 1 < 3
 Generators.tests.cpp:<line number>: passed: chunk2.size() == 2 for: 2 == 2
 Generators.tests.cpp:<line number>: passed: chunk2.front() == chunk2.back() for: 2 == 2
 Generators.tests.cpp:<line number>: passed: chunk2.front() < 3 for: 2 < 3
+Generators.tests.cpp:<line number>: passed: chunk2.size() == 0 for: 0 == 0
+Generators.tests.cpp:<line number>: passed: chunk2.size() == 0 for: 0 == 0
+Generators.tests.cpp:<line number>: passed: chunk2.size() == 0 for: 0 == 0
 Generators.tests.cpp:<line number>: passed: chunk(2, value(1)), Catch::GeneratorException
 Generators.tests.cpp:<line number>: passed: j < i for: -3 < 1
 Generators.tests.cpp:<line number>: passed: j < i for: -2 < 1

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

@@ -1381,5 +1381,5 @@ due to unexpected exception with message:
 
 ===============================================================================
 test cases:  295 |  221 passed |  70 failed |  4 failed as expected
-assertions: 1547 | 1395 passed | 131 failed | 21 failed as expected
+assertions: 1550 | 1398 passed | 131 failed | 21 failed as expected
 

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

@@ -3547,6 +3547,45 @@ Generators.tests.cpp:<line number>: PASSED:
 with expansion:
   2 < 3
 
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Chunking a generator into sized pieces
+  Chunk size of zero
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( chunk2.size() == 0 )
+with expansion:
+  0 == 0
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Chunking a generator into sized pieces
+  Chunk size of zero
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( chunk2.size() == 0 )
+with expansion:
+  0 == 0
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Chunking a generator into sized pieces
+  Chunk size of zero
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( chunk2.size() == 0 )
+with expansion:
+  0 == 0
+
 -------------------------------------------------------------------------------
 Generators -- adapters
   Chunking a generator into sized pieces
@@ -12335,5 +12374,5 @@ Misc.tests.cpp:<line number>: PASSED:
 
 ===============================================================================
 test cases:  295 |  205 passed |  86 failed |  4 failed as expected
-assertions: 1564 | 1395 passed | 148 failed | 21 failed as expected
+assertions: 1567 | 1398 passed | 148 failed | 21 failed as expected
 

projects/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="132" tests="1565" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
+  <testsuite name="<exe-name>" errors="17" failures="132" tests="1568" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
     <properties>
       <property name="filters" value="~[!nonportable]~[!benchmark]~[approvals]"/>
       <property name="random-seed" value="1"/>
@@ -416,6 +416,7 @@ Message.tests.cpp:<line number>
     <testcase classname="<exe-name>.global" name="Generators -- adapters/Repeating a generator" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="Generators -- adapters/Chunking a generator into sized pieces/Number of elements in source is divisible by chunk size" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="Generators -- adapters/Chunking a generator into sized pieces/Number of elements in source is not divisible by chunk size" time="{duration}"/>
+    <testcase classname="<exe-name>.global" name="Generators -- adapters/Chunking a generator into sized pieces/Chunk size of zero" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="Generators -- adapters/Chunking a generator into sized pieces/Throws on too small generators" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="Generators -- simple/one" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="Generators -- simple/two" time="{duration}"/>

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

@@ -4260,6 +4260,48 @@ Nor would this
         </Section>
         <OverallResults successes="3" failures="0" expectedFailures="0"/>
       </Section>
+      <Section name="Chunking a generator into sized pieces" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Section name="Chunk size of zero" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+            <Original>
+              chunk2.size() == 0
+            </Original>
+            <Expanded>
+              0 == 0
+            </Expanded>
+          </Expression>
+          <OverallResults successes="1" failures="0" expectedFailures="0"/>
+        </Section>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Chunking a generator into sized pieces" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Section name="Chunk size of zero" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+            <Original>
+              chunk2.size() == 0
+            </Original>
+            <Expanded>
+              0 == 0
+            </Expanded>
+          </Expression>
+          <OverallResults successes="1" failures="0" expectedFailures="0"/>
+        </Section>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Chunking a generator into sized pieces" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Section name="Chunk size of zero" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+            <Original>
+              chunk2.size() == 0
+            </Original>
+            <Expanded>
+              0 == 0
+            </Expanded>
+          </Expression>
+          <OverallResults successes="1" failures="0" expectedFailures="0"/>
+        </Section>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
       <Section name="Chunking a generator into sized pieces" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
         <Section name="Throws on too small generators" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
           <Expression success="true" type="REQUIRE_THROWS_AS" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
@@ -14692,7 +14734,7 @@ loose text artifact
       </Section>
       <OverallResult success="true"/>
     </TestCase>
-    <OverallResults successes="1395" failures="149" expectedFailures="21"/>
+    <OverallResults successes="1398" failures="149" expectedFailures="21"/>
   </Group>
-  <OverallResults successes="1395" failures="148" expectedFailures="21"/>
+  <OverallResults successes="1398" failures="148" expectedFailures="21"/>
 </Catch>

projects/SelfTest/UsageTests/Generators.tests.cpp

@@ -167,6 +167,10 @@ TEST_CASE("Generators -- adapters", "[generators][generic]") {
             REQUIRE(chunk2.front() == chunk2.back());
             REQUIRE(chunk2.front() < 3);
         }
+        SECTION("Chunk size of zero") {
+            auto chunk2 = GENERATE(take(3, chunk(0, value(1))));
+            REQUIRE(chunk2.size() == 0);
+        }
         SECTION("Throws on too small generators") {
             using namespace Catch::Generators;
             REQUIRE_THROWS_AS(chunk(2, value(1)), Catch::GeneratorException);