Make JSONWriter's number handling locale-independent

Closes #3176

18 files changed, 205 insertions, 18 deletions

diff --git a/tests/SelfTest/Baselines/automake.sw.approved.txt b/tests/SelfTest/Baselines/automake.sw.approved.txt
index 5018a19a..b0028998 100644
--- a/tests/SelfTest/Baselines/automake.sw.approved.txt
+++ b/tests/SelfTest/Baselines/automake.sw.approved.txt
@@ -190,6 +190,7 @@ Nor would this
 :test-result: PASS Inequality checks that should succeed
 :test-result: PASS JsonWriter
 :test-result: PASS JsonWriter escapes characters in strings properly
+:test-result: PASS JsonWriter serializes numbers independently of the global locale
 :test-result: PASS Lambdas in assertions
 :test-result: PASS Less-than inequalities with different epsilons
 :test-result: PASS ManuallyRegistered
diff --git a/tests/SelfTest/Baselines/automake.sw.multi.approved.txt b/tests/SelfTest/Baselines/automake.sw.multi.approved.txt
index 4f9a9441..9602395a 100644
--- a/tests/SelfTest/Baselines/automake.sw.multi.approved.txt
+++ b/tests/SelfTest/Baselines/automake.sw.multi.approved.txt
@@ -188,6 +188,7 @@
 :test-result: PASS Inequality checks that should succeed
 :test-result: PASS JsonWriter
 :test-result: PASS JsonWriter escapes characters in strings properly
+:test-result: PASS JsonWriter serializes numbers independently of the global locale
 :test-result: PASS Lambdas in assertions
 :test-result: PASS Less-than inequalities with different epsilons
 :test-result: PASS ManuallyRegistered
diff --git a/tests/SelfTest/Baselines/compact.sw.approved.txt b/tests/SelfTest/Baselines/compact.sw.approved.txt
index cb90a0f5..d669bce4 100644
--- a/tests/SelfTest/Baselines/compact.sw.approved.txt
+++ b/tests/SelfTest/Baselines/compact.sw.approved.txt
@@ -1248,6 +1248,20 @@ Json.tests.cpp:<line number>: passed: sstream.str() == "\"\\n\"" for: ""\n"" ==
 Json.tests.cpp:<line number>: passed: sstream.str() == "\"\\r\"" for: ""\r"" == ""\r""
 Json.tests.cpp:<line number>: passed: sstream.str() == "\"\\t\"" for: ""\t"" == ""\t""
 Json.tests.cpp:<line number>: passed: sstream.str() == "\"\\\\/\\t\\r\\n\"" for: ""\\/\t\r\n"" == ""\\/\t\r\n""
+Json.tests.cpp:<line number>: passed: sstream.str(), ContainsSubstring( "\"double\": 1.5," ) && ContainsSubstring( "\"int\": 1234567," ) && ContainsSubstring( "\"bool-1\": true," ) && ContainsSubstring( "\"bool-2\": false," ) && ContainsSubstring( "\"array\": [\n    2.5,\n    1234567\n  ]\n}" ) for: "{
+  "double": 1.5,
+  "int": 1234567,
+  "bool-1": true,
+  "bool-2": false,
+  "array": [
+    2.5,
+    1234567
+  ]
+}" ( contains: ""double": 1.5," and contains: ""int": 1234567," and contains: ""bool-1": true," and contains: ""bool-2": false," and contains: ""array": [
+    2.5,
+    1234567
+  ]
+}" )
 Compilation.tests.cpp:<line number>: passed: []() { return true; }() for: true
 Approx.tests.cpp:<line number>: passed: d <= Approx( 1.24 ) for: 1.22999999999999998
 <=
@@ -3000,7 +3014,7 @@ 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:  451 |  331 passed |  96 failed | 6 skipped | 18 failed as expected
-assertions: 2416 | 2215 passed | 158 failed | 43 failed as expected
+test cases:  452 |  332 passed |  96 failed | 6 skipped | 18 failed as expected
+assertions: 2417 | 2216 passed | 158 failed | 43 failed as expected
 
 
diff --git a/tests/SelfTest/Baselines/compact.sw.multi.approved.txt b/tests/SelfTest/Baselines/compact.sw.multi.approved.txt
index 39c260af..712b1259 100644
--- a/tests/SelfTest/Baselines/compact.sw.multi.approved.txt
+++ b/tests/SelfTest/Baselines/compact.sw.multi.approved.txt
@@ -1246,6 +1246,20 @@ Json.tests.cpp:<line number>: passed: sstream.str() == "\"\\n\"" for: ""\n"" ==
 Json.tests.cpp:<line number>: passed: sstream.str() == "\"\\r\"" for: ""\r"" == ""\r""
 Json.tests.cpp:<line number>: passed: sstream.str() == "\"\\t\"" for: ""\t"" == ""\t""
 Json.tests.cpp:<line number>: passed: sstream.str() == "\"\\\\/\\t\\r\\n\"" for: ""\\/\t\r\n"" == ""\\/\t\r\n""
+Json.tests.cpp:<line number>: passed: sstream.str(), ContainsSubstring( "\"double\": 1.5," ) && ContainsSubstring( "\"int\": 1234567," ) && ContainsSubstring( "\"bool-1\": true," ) && ContainsSubstring( "\"bool-2\": false," ) && ContainsSubstring( "\"array\": [\n    2.5,\n    1234567\n  ]\n}" ) for: "{
+  "double": 1.5,
+  "int": 1234567,
+  "bool-1": true,
+  "bool-2": false,
+  "array": [
+    2.5,
+    1234567
+  ]
+}" ( contains: ""double": 1.5," and contains: ""int": 1234567," and contains: ""bool-1": true," and contains: ""bool-2": false," and contains: ""array": [
+    2.5,
+    1234567
+  ]
+}" )
 Compilation.tests.cpp:<line number>: passed: []() { return true; }() for: true
 Approx.tests.cpp:<line number>: passed: d <= Approx( 1.24 ) for: 1.22999999999999998
 <=
@@ -2989,7 +3003,7 @@ 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:  451 |  331 passed |  96 failed | 6 skipped | 18 failed as expected
-assertions: 2416 | 2215 passed | 158 failed | 43 failed as expected
+test cases:  452 |  332 passed |  96 failed | 6 skipped | 18 failed as expected
+assertions: 2417 | 2216 passed | 158 failed | 43 failed as expected
 
 
diff --git a/tests/SelfTest/Baselines/console.std.approved.txt b/tests/SelfTest/Baselines/console.std.approved.txt
index 78c3d640..a833734a 100644
--- a/tests/SelfTest/Baselines/console.std.approved.txt
+++ b/tests/SelfTest/Baselines/console.std.approved.txt
@@ -1743,6 +1743,6 @@ due to unexpected exception with message:
   Why would you throw a std::string?
 
 ===============================================================================
-test cases:  451 |  349 passed |  76 failed | 7 skipped | 19 failed as expected
-assertions: 2394 | 2215 passed | 136 failed | 43 failed as expected
+test cases:  452 |  350 passed |  76 failed | 7 skipped | 19 failed as expected
+assertions: 2395 | 2216 passed | 136 failed | 43 failed as expected
 
diff --git a/tests/SelfTest/Baselines/console.sw.approved.txt b/tests/SelfTest/Baselines/console.sw.approved.txt
index add1eaaf..2de0a3a5 100644
--- a/tests/SelfTest/Baselines/console.sw.approved.txt
+++ b/tests/SelfTest/Baselines/console.sw.approved.txt
@@ -8220,6 +8220,31 @@ with expansion:
   ""\\/\t\r\n"" == ""\\/\t\r\n""
 
 -------------------------------------------------------------------------------
+JsonWriter serializes numbers independently of the global locale
+-------------------------------------------------------------------------------
+Json.tests.cpp:<line number>
+...............................................................................
+
+Json.tests.cpp:<line number>: PASSED:
+  REQUIRE_THAT( sstream.str(), ContainsSubstring( "\"double\": 1.5," ) && ContainsSubstring( "\"int\": 1234567," ) && ContainsSubstring( "\"bool-1\": true," ) && ContainsSubstring( "\"bool-2\": false," ) && ContainsSubstring( "\"array\": [\n    2.5,\n    1234567\n  ]\n}" ) )
+with expansion:
+  "{
+    "double": 1.5,
+    "int": 1234567,
+    "bool-1": true,
+    "bool-2": false,
+    "array": [
+      2.5,
+      1234567
+    ]
+  }" ( contains: ""double": 1.5," and contains: ""int": 1234567," and contains:
+  ""bool-1": true," and contains: ""bool-2": false," and contains: ""array": [
+      2.5,
+      1234567
+    ]
+  }" )
+
+-------------------------------------------------------------------------------
 Lambdas in assertions
 -------------------------------------------------------------------------------
 Compilation.tests.cpp:<line number>
@@ -20134,6 +20159,6 @@ Misc.tests.cpp:<line number>
 Misc.tests.cpp:<line number>: PASSED:
 
 ===============================================================================
-test cases:  451 |  331 passed |  96 failed | 6 skipped | 18 failed as expected
-assertions: 2416 | 2215 passed | 158 failed | 43 failed as expected
+test cases:  452 |  332 passed |  96 failed | 6 skipped | 18 failed as expected
+assertions: 2417 | 2216 passed | 158 failed | 43 failed as expected
 
diff --git a/tests/SelfTest/Baselines/console.sw.multi.approved.txt b/tests/SelfTest/Baselines/console.sw.multi.approved.txt
index 07195577..9b6f023c 100644
--- a/tests/SelfTest/Baselines/console.sw.multi.approved.txt
+++ b/tests/SelfTest/Baselines/console.sw.multi.approved.txt
@@ -8218,6 +8218,31 @@ with expansion:
   ""\\/\t\r\n"" == ""\\/\t\r\n""
 
 -------------------------------------------------------------------------------
+JsonWriter serializes numbers independently of the global locale
+-------------------------------------------------------------------------------
+Json.tests.cpp:<line number>
+...............................................................................
+
+Json.tests.cpp:<line number>: PASSED:
+  REQUIRE_THAT( sstream.str(), ContainsSubstring( "\"double\": 1.5," ) && ContainsSubstring( "\"int\": 1234567," ) && ContainsSubstring( "\"bool-1\": true," ) && ContainsSubstring( "\"bool-2\": false," ) && ContainsSubstring( "\"array\": [\n    2.5,\n    1234567\n  ]\n}" ) )
+with expansion:
+  "{
+    "double": 1.5,
+    "int": 1234567,
+    "bool-1": true,
+    "bool-2": false,
+    "array": [
+      2.5,
+      1234567
+    ]
+  }" ( contains: ""double": 1.5," and contains: ""int": 1234567," and contains:
+  ""bool-1": true," and contains: ""bool-2": false," and contains: ""array": [
+      2.5,
+      1234567
+    ]
+  }" )
+
+-------------------------------------------------------------------------------
 Lambdas in assertions
 -------------------------------------------------------------------------------
 Compilation.tests.cpp:<line number>
@@ -20123,6 +20148,6 @@ Misc.tests.cpp:<line number>
 Misc.tests.cpp:<line number>: PASSED:
 
 ===============================================================================
-test cases:  451 |  331 passed |  96 failed | 6 skipped | 18 failed as expected
-assertions: 2416 | 2215 passed | 158 failed | 43 failed as expected
+test cases:  452 |  332 passed |  96 failed | 6 skipped | 18 failed as expected
+assertions: 2417 | 2216 passed | 158 failed | 43 failed as expected
 
diff --git a/tests/SelfTest/Baselines/junit.sw.approved.txt b/tests/SelfTest/Baselines/junit.sw.approved.txt
index 328b466c..c84565d5 100644
--- a/tests/SelfTest/Baselines/junit.sw.approved.txt
+++ b/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="141" skipped="12" tests="2428" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
+  <testsuite name="<exe-name>" errors="17" failures="141" skipped="12" tests="2429" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
     <properties>
       <property name="random-seed" value="1"/>
       <property name="filters" value="&quot;*&quot; ~[!nonportable] ~[!benchmark] ~[approvals]"/>
@@ -774,6 +774,7 @@ at Condition.tests.cpp:<line number>
     <testcase classname="<exe-name>.global" name="JsonWriter escapes characters in strings properly/carriage return in a string is escaped" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="JsonWriter escapes characters in strings properly/tab in a string is escaped" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="JsonWriter escapes characters in strings properly/combination of characters is escaped" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="JsonWriter serializes numbers independently of the global locale" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Lambdas in assertions" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Less-than inequalities with different epsilons" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="ManuallyRegistered" time="{duration}" status="run"/>
diff --git a/tests/SelfTest/Baselines/junit.sw.multi.approved.txt b/tests/SelfTest/Baselines/junit.sw.multi.approved.txt
index 403ed251..f4ff03d6 100644
--- a/tests/SelfTest/Baselines/junit.sw.multi.approved.txt
+++ b/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="141" skipped="12" tests="2428" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
+  <testsuite name="<exe-name>" errors="17" failures="141" skipped="12" tests="2429" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
     <properties>
       <property name="random-seed" value="1"/>
       <property name="filters" value="&quot;*&quot; ~[!nonportable] ~[!benchmark] ~[approvals]"/>
@@ -773,6 +773,7 @@ at Condition.tests.cpp:<line number>
     <testcase classname="<exe-name>.global" name="JsonWriter escapes characters in strings properly/carriage return in a string is escaped" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="JsonWriter escapes characters in strings properly/tab in a string is escaped" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="JsonWriter escapes characters in strings properly/combination of characters is escaped" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="JsonWriter serializes numbers independently of the global locale" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Lambdas in assertions" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Less-than inequalities with different epsilons" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="ManuallyRegistered" time="{duration}" status="run"/>
diff --git a/tests/SelfTest/Baselines/sonarqube.sw.approved.txt b/tests/SelfTest/Baselines/sonarqube.sw.approved.txt
index f9e851fc..dceaca40 100644
--- a/tests/SelfTest/Baselines/sonarqube.sw.approved.txt
+++ b/tests/SelfTest/Baselines/sonarqube.sw.approved.txt
@@ -262,6 +262,7 @@ at AssertionHandler.tests.cpp:<line number>
     <testCase name="JsonWriter escapes characters in strings properly/carriage return in a string is escaped" duration="{duration}"/>
     <testCase name="JsonWriter escapes characters in strings properly/tab in a string is escaped" duration="{duration}"/>
     <testCase name="JsonWriter escapes characters in strings properly/combination of characters is escaped" duration="{duration}"/>
+    <testCase name="JsonWriter serializes numbers independently of the global locale" duration="{duration}"/>
   </file>
   <file path="tests/<exe-name>/IntrospectiveTests/Parse.tests.cpp">
     <testCase name="Parse uints" duration="{duration}"/>
diff --git a/tests/SelfTest/Baselines/sonarqube.sw.multi.approved.txt b/tests/SelfTest/Baselines/sonarqube.sw.multi.approved.txt
index e1ede12c..250b45ae 100644
--- a/tests/SelfTest/Baselines/sonarqube.sw.multi.approved.txt
+++ b/tests/SelfTest/Baselines/sonarqube.sw.multi.approved.txt
@@ -261,6 +261,7 @@ at AssertionHandler.tests.cpp:<line number>
     <testCase name="JsonWriter escapes characters in strings properly/carriage return in a string is escaped" duration="{duration}"/>
     <testCase name="JsonWriter escapes characters in strings properly/tab in a string is escaped" duration="{duration}"/>
     <testCase name="JsonWriter escapes characters in strings properly/combination of characters is escaped" duration="{duration}"/>
+    <testCase name="JsonWriter serializes numbers independently of the global locale" duration="{duration}"/>
   </file>
   <file path="tests/<exe-name>/IntrospectiveTests/Parse.tests.cpp">
     <testCase name="Parse uints" duration="{duration}"/>
diff --git a/tests/SelfTest/Baselines/tap.sw.approved.txt b/tests/SelfTest/Baselines/tap.sw.approved.txt
index 7624d140..7e9a19d6 100644
--- a/tests/SelfTest/Baselines/tap.sw.approved.txt
+++ b/tests/SelfTest/Baselines/tap.sw.approved.txt
@@ -2054,6 +2054,8 @@ ok {test-number} - sstream.str() == "\"\\r\"" for: ""\r"" == ""\r""
 ok {test-number} - sstream.str() == "\"\\t\"" for: ""\t"" == ""\t""
 # JsonWriter escapes characters in strings properly
 ok {test-number} - sstream.str() == "\"\\\\/\\t\\r\\n\"" for: ""\\/\t\r\n"" == ""\\/\t\r\n""
+# JsonWriter serializes numbers independently of the global locale
+ok {test-number} - sstream.str(), ContainsSubstring( "\"double\": 1.5," ) && ContainsSubstring( "\"int\": 1234567," ) && ContainsSubstring( "\"bool-1\": true," ) && ContainsSubstring( "\"bool-2\": false," ) && ContainsSubstring( "\"array\": [\n    2.5,\n    1234567\n  ]\n}" ) for: "{   "double": 1.5,   "int": 1234567,   "bool-1": true,   "bool-2": false,   "array": [     2.5,     1234567   ] }" ( contains: ""double": 1.5," and contains: ""int": 1234567," and contains: ""bool-1": true," and contains: ""bool-2": false," and contains: ""array": [     2.5,     1234567   ] }" )
 # Lambdas in assertions
 ok {test-number} - []() { return true; }() for: true
 # Less-than inequalities with different epsilons
@@ -4851,5 +4853,5 @@ ok {test-number} - q3 == 23. for: 23.0 == 23.0
 ok {test-number} -
 # xmlentitycheck
 ok {test-number} -
-1..2428
+1..2429
 
diff --git a/tests/SelfTest/Baselines/tap.sw.multi.approved.txt b/tests/SelfTest/Baselines/tap.sw.multi.approved.txt
index ed653421..edcb7813 100644
--- a/tests/SelfTest/Baselines/tap.sw.multi.approved.txt
+++ b/tests/SelfTest/Baselines/tap.sw.multi.approved.txt
@@ -2052,6 +2052,8 @@ ok {test-number} - sstream.str() == "\"\\r\"" for: ""\r"" == ""\r""
 ok {test-number} - sstream.str() == "\"\\t\"" for: ""\t"" == ""\t""
 # JsonWriter escapes characters in strings properly
 ok {test-number} - sstream.str() == "\"\\\\/\\t\\r\\n\"" for: ""\\/\t\r\n"" == ""\\/\t\r\n""
+# JsonWriter serializes numbers independently of the global locale
+ok {test-number} - sstream.str(), ContainsSubstring( "\"double\": 1.5," ) && ContainsSubstring( "\"int\": 1234567," ) && ContainsSubstring( "\"bool-1\": true," ) && ContainsSubstring( "\"bool-2\": false," ) && ContainsSubstring( "\"array\": [\n    2.5,\n    1234567\n  ]\n}" ) for: "{   "double": 1.5,   "int": 1234567,   "bool-1": true,   "bool-2": false,   "array": [     2.5,     1234567   ] }" ( contains: ""double": 1.5," and contains: ""int": 1234567," and contains: ""bool-1": true," and contains: ""bool-2": false," and contains: ""array": [     2.5,     1234567   ] }" )
 # Lambdas in assertions
 ok {test-number} - []() { return true; }() for: true
 # Less-than inequalities with different epsilons
@@ -4840,5 +4842,5 @@ ok {test-number} - q3 == 23. for: 23.0 == 23.0
 ok {test-number} -
 # xmlentitycheck
 ok {test-number} -
-1..2428
+1..2429
 
diff --git a/tests/SelfTest/Baselines/teamcity.sw.approved.txt b/tests/SelfTest/Baselines/teamcity.sw.approved.txt
index bbd587ff..fc65c1c6 100644
--- a/tests/SelfTest/Baselines/teamcity.sw.approved.txt
+++ b/tests/SelfTest/Baselines/teamcity.sw.approved.txt
@@ -470,6 +470,8 @@
 ##teamcity[testFinished name='JsonWriter' duration="{duration}"]
 ##teamcity[testStarted name='JsonWriter escapes characters in strings properly']
 ##teamcity[testFinished name='JsonWriter escapes characters in strings properly' duration="{duration}"]
+##teamcity[testStarted name='JsonWriter serializes numbers independently of the global locale']
+##teamcity[testFinished name='JsonWriter serializes numbers independently of the global locale' duration="{duration}"]
 ##teamcity[testStarted name='Lambdas in assertions']
 ##teamcity[testFinished name='Lambdas in assertions' duration="{duration}"]
 ##teamcity[testStarted name='Less-than inequalities with different epsilons']
diff --git a/tests/SelfTest/Baselines/teamcity.sw.multi.approved.txt b/tests/SelfTest/Baselines/teamcity.sw.multi.approved.txt
index fb73387f..f0a28ed7 100644
--- a/tests/SelfTest/Baselines/teamcity.sw.multi.approved.txt
+++ b/tests/SelfTest/Baselines/teamcity.sw.multi.approved.txt
@@ -470,6 +470,8 @@
 ##teamcity[testFinished name='JsonWriter' duration="{duration}"]
 ##teamcity[testStarted name='JsonWriter escapes characters in strings properly']
 ##teamcity[testFinished name='JsonWriter escapes characters in strings properly' duration="{duration}"]
+##teamcity[testStarted name='JsonWriter serializes numbers independently of the global locale']
+##teamcity[testFinished name='JsonWriter serializes numbers independently of the global locale' duration="{duration}"]
 ##teamcity[testStarted name='Lambdas in assertions']
 ##teamcity[testFinished name='Lambdas in assertions' duration="{duration}"]
 ##teamcity[testStarted name='Less-than inequalities with different epsilons']
diff --git a/tests/SelfTest/Baselines/xml.sw.approved.txt b/tests/SelfTest/Baselines/xml.sw.approved.txt
index 933094d3..31801eef 100644
--- a/tests/SelfTest/Baselines/xml.sw.approved.txt
+++ b/tests/SelfTest/Baselines/xml.sw.approved.txt
@@ -9894,6 +9894,30 @@ Approx( 3.14150000000000018 )
     </Section>
     <OverallResult success="true" skips="0"/>
   </TestCase>
+  <TestCase name="JsonWriter serializes numbers independently of the global locale" tags="[JsonWriter]" filename="tests/<exe-name>/IntrospectiveTests/Json.tests.cpp" >
+    <Expression success="true" type="REQUIRE_THAT" filename="tests/<exe-name>/IntrospectiveTests/Json.tests.cpp" >
+      <Original>
+        sstream.str(), ContainsSubstring( "\"double\": 1.5," ) &amp;&amp; ContainsSubstring( "\"int\": 1234567," ) &amp;&amp; ContainsSubstring( "\"bool-1\": true," ) &amp;&amp; ContainsSubstring( "\"bool-2\": false," ) &amp;&amp; ContainsSubstring( "\"array\": [\n    2.5,\n    1234567\n  ]\n}" )
+      </Original>
+      <Expanded>
+        "{
+  "double": 1.5,
+  "int": 1234567,
+  "bool-1": true,
+  "bool-2": false,
+  "array": [
+    2.5,
+    1234567
+  ]
+}" ( contains: ""double": 1.5," and contains: ""int": 1234567," and contains: ""bool-1": true," and contains: ""bool-2": false," and contains: ""array": [
+    2.5,
+    1234567
+  ]
+}" )
+      </Expanded>
+    </Expression>
+    <OverallResult success="true" skips="0"/>
+  </TestCase>
   <TestCase name="Lambdas in assertions" filename="tests/<exe-name>/UsageTests/Compilation.tests.cpp" >
     <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Compilation.tests.cpp" >
       <Original>
@@ -23385,6 +23409,6 @@ Approx( -1.95996398454005449 )
     </Section>
     <OverallResult success="true" skips="0"/>
   </TestCase>
-  <OverallResults successes="2215" failures="158" expectedFailures="43" skips="12"/>
-  <OverallResultsCases successes="331" failures="96" expectedFailures="18" skips="6"/>
+  <OverallResults successes="2216" failures="158" expectedFailures="43" skips="12"/>
+  <OverallResultsCases successes="332" failures="96" expectedFailures="18" skips="6"/>
 </Catch2TestRun>
diff --git a/tests/SelfTest/Baselines/xml.sw.multi.approved.txt b/tests/SelfTest/Baselines/xml.sw.multi.approved.txt
index 646f0c72..b24ec091 100644
--- a/tests/SelfTest/Baselines/xml.sw.multi.approved.txt
+++ b/tests/SelfTest/Baselines/xml.sw.multi.approved.txt
@@ -9894,6 +9894,30 @@ Approx( 3.14150000000000018 )
     </Section>
     <OverallResult success="true" skips="0"/>
   </TestCase>
+  <TestCase name="JsonWriter serializes numbers independently of the global locale" tags="[JsonWriter]" filename="tests/<exe-name>/IntrospectiveTests/Json.tests.cpp" >
+    <Expression success="true" type="REQUIRE_THAT" filename="tests/<exe-name>/IntrospectiveTests/Json.tests.cpp" >
+      <Original>
+        sstream.str(), ContainsSubstring( "\"double\": 1.5," ) &amp;&amp; ContainsSubstring( "\"int\": 1234567," ) &amp;&amp; ContainsSubstring( "\"bool-1\": true," ) &amp;&amp; ContainsSubstring( "\"bool-2\": false," ) &amp;&amp; ContainsSubstring( "\"array\": [\n    2.5,\n    1234567\n  ]\n}" )
+      </Original>
+      <Expanded>
+        "{
+  "double": 1.5,
+  "int": 1234567,
+  "bool-1": true,
+  "bool-2": false,
+  "array": [
+    2.5,
+    1234567
+  ]
+}" ( contains: ""double": 1.5," and contains: ""int": 1234567," and contains: ""bool-1": true," and contains: ""bool-2": false," and contains: ""array": [
+    2.5,
+    1234567
+  ]
+}" )
+      </Expanded>
+    </Expression>
+    <OverallResult success="true" skips="0"/>
+  </TestCase>
   <TestCase name="Lambdas in assertions" filename="tests/<exe-name>/UsageTests/Compilation.tests.cpp" >
     <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Compilation.tests.cpp" >
       <Original>
@@ -23384,6 +23408,6 @@ Approx( -1.95996398454005449 )
     </Section>
     <OverallResult success="true" skips="0"/>
   </TestCase>
-  <OverallResults successes="2215" failures="158" expectedFailures="43" skips="12"/>
-  <OverallResultsCases successes="331" failures="96" expectedFailures="18" skips="6"/>
+  <OverallResults successes="2216" failures="158" expectedFailures="43" skips="12"/>
+  <OverallResultsCases successes="332" failures="96" expectedFailures="18" skips="6"/>
 </Catch2TestRun>
diff --git a/tests/SelfTest/IntrospectiveTests/Json.tests.cpp b/tests/SelfTest/IntrospectiveTests/Json.tests.cpp
index fae1c843..4f6789ec 100644
--- a/tests/SelfTest/IntrospectiveTests/Json.tests.cpp
+++ b/tests/SelfTest/IntrospectiveTests/Json.tests.cpp
@@ -12,6 +12,7 @@
 #include <catch2/internal/catch_jsonwriter.hpp>
 #include <catch2/matchers/catch_matchers_string.hpp>
 
+#include <locale>
 #include <sstream>
 
 namespace {
@@ -20,6 +21,27 @@ namespace {
         return os << "custom";
     }
 
+    // Obviously wrong numpunct if it is actually used by the JSON writer.
+    class TestNumpunct : public std::numpunct<char> {
+        char do_decimal_point() const override { return '?'; }
+        char do_thousands_sep() const override { return '!'; }
+        std::string do_grouping() const override { return "\1"; }
+        std::string do_truename() const override { return "real"; }
+        std::string do_falsename() const override { return "fake"; }
+    };
+
+    class LocaleGuard {
+        std::locale m_previous_locale;
+
+    public:
+        explicit LocaleGuard( std::locale const& locale ):
+            m_previous_locale{ std::locale() } {
+            std::locale::global( locale );
+        }
+
+        ~LocaleGuard() { std::locale::global( m_previous_locale ); }
+    };
+
 TEST_CASE( "JsonWriter", "[JSON][JsonWriter]" ) {
 
     std::stringstream stream;
@@ -152,6 +174,31 @@ TEST_CASE( "JsonWriter escapes characters in strings properly", "[JsonWriter]" )
     }
 }
 
+TEST_CASE( "JsonWriter serializes numbers independently of the global locale",
+           "[JsonWriter]" ) {
+    using Catch::Matchers::ContainsSubstring;
+
+    LocaleGuard locale_guard{ std::locale{ std::locale(), new TestNumpunct } };
+
+    std::stringstream sstream;
+    {
+        auto writer = Catch::JsonValueWriter{ sstream }.writeObject();
+        writer.write( "double" ).write( 1.5 );
+        writer.write( "int" ).write( 1234567 );
+        writer.write( "bool-1" ).write( true );
+        writer.write( "bool-2" ).write( false );
+        writer.write( "array" ).writeArray().write( 2.5 ).write( 1234567 );
+    }
+
+    REQUIRE_THAT( sstream.str(),
+                  ContainsSubstring( "\"double\": 1.5," ) &&
+                      ContainsSubstring( "\"int\": 1234567," ) &&
+                      ContainsSubstring( "\"bool-1\": true," ) &&
+                      ContainsSubstring( "\"bool-2\": false," ) &&
+                      ContainsSubstring(
+                          "\"array\": [\n    2.5,\n    1234567\n  ]\n}" ) );
+}
+
 TEST_CASE( "JsonWriter benchmarks", "[JsonWriter][!benchmark]" ) {
     const auto input_length = GENERATE( as<size_t>{}, 10, 100, 10'000 );
     std::string test_input( input_length, 'a' );