CTest: Provide more detailed information on resource allocation error

Source/CTest/cmCTestMultiProcessHandler.cxx

@@ -197,7 +197,39 @@ bool cmCTestMultiProcessHandler::StartTestProcess(int test)
   this->LockResources(test);
 
   if (!this->ResourceAllocationErrors[test].empty()) {
-    testRun->StartFailure("Insufficient resources", "Failed to start");
+    std::ostringstream e;
+    e << "Insufficient resources for test " << this->Properties[test]->Name
+      << ":\n\n";
+    for (auto const& it : this->ResourceAllocationErrors[test]) {
+      switch (it.second) {
+        case ResourceAllocationError::NoResourceType:
+          e << "  Test requested resources of type '" << it.first
+            << "' which does not exist\n";
+          break;
+
+        case ResourceAllocationError::InsufficientResources:
+          e << "  Test requested resources of type '" << it.first
+            << "' in the following amounts:\n";
+          for (auto const& group : this->Properties[test]->ResourceGroups) {
+            for (auto const& requirement : group) {
+              if (requirement.ResourceType == it.first) {
+                e << "    " << requirement.SlotsNeeded
+                  << (requirement.SlotsNeeded == 1 ? " slot\n" : " slots\n");
+              }
+            }
+          }
+          e << "  but only the following units were available:\n";
+          for (auto const& res :
+               this->ResourceAllocator.GetResources().at(it.first)) {
+            e << "    '" << res.first << "': " << res.second.Total
+              << (res.second.Total == 1 ? " slot\n" : " slots\n");
+          }
+          break;
+      }
+      e << "\n";
+    }
+    e << "Resource spec file:\n\n  " << this->TestHandler->ResourceSpecFile;
+    testRun->StartFailure(e.str(), "Insufficient resources");
     this->FinishTestProcess(testRun, false);
     return false;
   }

Source/CTest/cmCTestTestHandler.cxx

@@ -548,6 +548,7 @@ bool cmCTestTestHandler::ProcessOptions()
   val = this->GetOption("ResourceSpecFile");
   if (val) {
     this->UseResourceSpec = true;
+    this->ResourceSpecFile = val;
     auto result = this->ResourceSpec.ReadFromJSONFile(val);
     if (result != cmCTestResourceSpec::ReadFileResult::READ_OK) {
       cmCTestLog(this->CTest, ERROR_MESSAGE,

Source/CTest/cmCTestTestHandler.h

@@ -338,6 +338,7 @@ private:
 
   bool UseResourceSpec;
   cmCTestResourceSpec ResourceSpec;
+  std::string ResourceSpecFile;
 
   void GenerateRegressionImages(cmXMLWriter& xml, const std::string& dart);
   cmsys::RegularExpression DartStuff1;

Tests/RunCMake/CTestResourceAllocation/notenough1-ctest-s-res-stderr.txt

@@ -1,4 +1,14 @@
-^Insufficient resources
+^Insufficient resources for test Test1:
+
+  Test requested resources of type 'fluxcapacitors' in the following amounts:
+    200 slots
+  but only the following units were available:
+    'outatime': 121 slots
+
+Resource spec file:
+
+  [^
+]*/Tests/RunCMake/CTestResourceAllocation/resspec.json
 CMake Error at [^
 ]*/Tests/RunCMake/CTestResourceAllocation/notenough1-ctest-s-res/test\.cmake:[0-9]+ \(message\):
   Tests did not pass$

Tests/RunCMake/CTestResourceAllocation/notenough2-ctest-s-res-stderr.txt

@@ -1,4 +1,11 @@
-^Insufficient resources
+^Insufficient resources for test Test1:
+
+  Test requested resources of type 'terminators' which does not exist
+
+Resource spec file:
+
+  [^
+]*/Tests/RunCMake/CTestResourceAllocation/resspec.json
 CMake Error at [^
 ]*/Tests/RunCMake/CTestResourceAllocation/notenough2-ctest-s-res/test\.cmake:[0-9]+ \(message\):
   Tests did not pass$

Tests/RunCMake/CTestResourceAllocation/notenough3-ctest-s-res-stderr.txt

@@ -1,4 +1,21 @@
-^Insufficient resources
+^Insufficient resources for test Test1:
+
+  Test requested resources of type 'widgets' in the following amounts:
+    12 slots
+  but only the following units were available:
+    '0': 4 slots
+    '1': 2 slots
+    '2': 4 slots
+    '3': 8 slots
+    '4': 1 slot
+    '5': 1 slot
+    '6': 1 slot
+    '7': 1 slot
+
+Resource spec file:
+
+  [^
+]*/Tests/RunCMake/CTestResourceAllocation/resspec.json
 CMake Error at [^
 ]*/Tests/RunCMake/CTestResourceAllocation/notenough3-ctest-s-res/test\.cmake:[0-9]+ \(message\):
   Tests did not pass$