Exclude uncoverable lines from code coverage (#3179)

* Use code coverage annotations in places that never can be covered

* Comments

* Increment goal

Co-authored-by: Anton Kolesnyk <antkmsft@users.noreply.github.com>

sdk/core/azure-core/src/azure_assert.cpp

@@ -3,6 +3,8 @@
 
 #include "azure/core/internal/azure_assert.hpp"
 
+// Calling this function would terminate program, therefore this function can't be covered in tests.
+// LCOV_EXCL_START
 [[noreturn]] void Azure::Core::_internal::AzureNoReturnPath(std::string const& msg)
 {
   // void msg for Release build where Assert is ignored
@@ -10,3 +12,4 @@
   _azure_ASSERT_MSG(false, msg);
   std::abort();
 }
+// LCOV_EXCL_STOP

sdk/core/azure-core/src/datetime.cpp

@@ -342,7 +342,10 @@ T ParseNumber(
   }
 
   ThrowParseError(description);
-  return T();
+
+  // ThrowParseError() will always throw, but there's no way to tell that to compiler, so a return
+  // statement is required. It is not possible to cover the return line with tests.
+  return T(); // LCOV_EXCL_LINE
 }
 
 template <typename T>

sdk/identity/azure-identity/src/managed_identity_credential.cpp

@@ -20,7 +20,9 @@ std::unique_ptr<_detail::ManagedIdentitySource> CreateManagedIdentitySource(
          AzureArcManagedIdentitySource::Create,
          ImdsManagedIdentitySource::Create};
 
-  for (auto create : managedIdentitySourceCreate)
+  // IMDS ManagedIdentity, which comes last in the list, will never return nullptr from Create().
+  // For that reason, it is not possible to cover that execution branch in tests.
+  for (auto create : managedIdentitySourceCreate) // LCOV_EXCL_LINE
   {
     if (auto source = create(clientId, options))
     {
@@ -28,8 +30,10 @@ std::unique_ptr<_detail::ManagedIdentitySource> CreateManagedIdentitySource(
     }
   }
 
+  // LCOV_EXCL_START
   throw AuthenticationException(
       "ManagedIdentityCredential authentication unavailable. No Managed Identity endpoint found.");
+  // LCOV_EXCL_STOP
 }
 } // namespace
 

sdk/identity/ci.yml

@@ -29,7 +29,7 @@ stages:
       CtestRegex: azure-identity.
       LiveTestCtestRegex: azure-identity.
       LineCoverageTarget: 99
-      BranchCoverageTarget: 62
+      BranchCoverageTarget: 63
       Artifacts:
         - Name: azure-identity
           Path: azure-identity