diff --git a/Modules/Core/Common/test/CMakeLists.txt b/Modules/Core/Common/test/CMakeLists.txt
index 50d316f30a7..24ff9c24e33 100644
--- a/Modules/Core/Common/test/CMakeLists.txt
+++ b/Modules/Core/Common/test/CMakeLists.txt
@@ -61,9 +61,6 @@ set(
   itkPointSetToImageFilterTest2.cxx
   itkSparseFieldLayerTest.cxx
   itkDataObjectTest.cxx
-  itkAtanRegularizedHeavisideStepFunctionTest1.cxx
-  itkHeavisideStepFunctionTest1.cxx
-  itkSinRegularizedHeavisideStepFunctionTest1.cxx
   itkPointGeometryTest.cxx
   itkNumberToStringTest.cxx
   itkTimeProbeTest.cxx
@@ -665,24 +662,6 @@ itk_add_test(
     ITKCommon1TestDriver
     itkDataObjectTest
 )
-itk_add_test(
-  NAME itkAtanRegularizedHeavisideStepFunctionTest1
-  COMMAND
-    ITKCommon1TestDriver
-    itkAtanRegularizedHeavisideStepFunctionTest1
-)
-itk_add_test(
-  NAME itkHeavisideStepFunctionTest1
-  COMMAND
-    ITKCommon1TestDriver
-    itkHeavisideStepFunctionTest1
-)
-itk_add_test(
-  NAME itkSinRegularizedHeavisideStepFunctionTest1
-  COMMAND
-    ITKCommon1TestDriver
-    itkSinRegularizedHeavisideStepFunctionTest1
-)
 itk_add_test(
   NAME itkPointGeometryTest
   COMMAND
@@ -1627,6 +1606,7 @@ set(
   itkFilterDispatchGTest.cxx
   itkThreadedIndexedContainerPartitionerGTest.cxx
   itkHashTableGTest.cxx
+  itkHeavisideStepFunctionGTest.cxx
   itkImportImageGTest.cxx
   itkImportContainerGTest.cxx
   itkPixelAccessGTest.cxx
diff --git a/Modules/Core/Common/test/itkAtanRegularizedHeavisideStepFunctionTest1.cxx b/Modules/Core/Common/test/itkAtanRegularizedHeavisideStepFunctionTest1.cxx
deleted file mode 100644
index 775e5ebaa00..00000000000
--- a/Modules/Core/Common/test/itkAtanRegularizedHeavisideStepFunctionTest1.cxx
+++ /dev/null
@@ -1,65 +0,0 @@
-/*=========================================================================
- *
- *  Copyright NumFOCUS
- *
- *  Licensed under the Apache License, Version 2.0 (the "License");
- *  you may not use this file except in compliance with the License.
- *  You may obtain a copy of the License at
- *
- *         https://www.apache.org/licenses/LICENSE-2.0.txt
- *
- *  Unless required by applicable law or agreed to in writing, software
- *  distributed under the License is distributed on an "AS IS" BASIS,
- *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *  See the License for the specific language governing permissions and
- *  limitations under the License.
- *
- *=========================================================================*/
-
-#include "itkAtanRegularizedHeavisideStepFunction.h"
-#include "itkTestingMacros.h"
-
-int
-itkAtanRegularizedHeavisideStepFunctionTest1(int, char *[])
-{
-  using InputType = double;
-  using OutputType = double;
-
-  using HeavisideFunctionBaseType = itk::AtanRegularizedHeavisideStepFunction<InputType, OutputType>;
-
-  auto functionBase0 = HeavisideFunctionBaseType::New();
-
-  std::cout << "GetNameOfClass() = " << functionBase0->GetNameOfClass() << std::endl;
-  functionBase0->Print(std::cout);
-
-  constexpr double epsilon{ -1.0 };
-
-  ITK_TRY_EXPECT_EXCEPTION(functionBase0->SetEpsilon(epsilon));
-
-
-  constexpr double epsilon0{ 1.0 };
-  constexpr double epsilon1{ 1e-4 };
-
-  ITK_TEST_SET_GET_VALUE(epsilon0, functionBase0->GetEpsilon());
-
-  functionBase0->SetEpsilon(epsilon1);
-  ITK_TEST_SET_GET_VALUE(epsilon1, functionBase0->GetEpsilon());
-
-  constexpr double epsilon2{ 0.5 };
-  functionBase0->SetEpsilon(epsilon2);
-
-  constexpr int minValue{ -20 };
-  constexpr int maxValue{ 20 };
-
-  constexpr InputType incValue{ 0.1 };
-
-  for (int x = minValue; x < maxValue; ++x)
-  {
-    const InputType  ix = x * incValue;
-    const OutputType f = functionBase0->Evaluate(ix);
-    const OutputType df = functionBase0->EvaluateDerivative(ix);
-    std::cout << ix << ' ' << f << ' ' << df << std::endl;
-  }
-
-  return EXIT_SUCCESS;
-}
diff --git a/Modules/Core/Common/test/itkHeavisideStepFunctionGTest.cxx b/Modules/Core/Common/test/itkHeavisideStepFunctionGTest.cxx
new file mode 100644
index 00000000000..f72cddf8ae7
--- /dev/null
+++ b/Modules/Core/Common/test/itkHeavisideStepFunctionGTest.cxx
@@ -0,0 +1,134 @@
+/*=========================================================================
+ *
+ *  Copyright NumFOCUS
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *         https://www.apache.org/licenses/LICENSE-2.0.txt
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *=========================================================================*/
+
+#include "itkAtanRegularizedHeavisideStepFunction.h"
+#include "itkHeavisideStepFunction.h"
+#include "itkSinRegularizedHeavisideStepFunction.h"
+
+#include "itkGTest.h"
+
+#include <iostream>
+
+// From itkHeavisideStepFunctionTest1.cxx
+TEST(HeavisideStepFunction, ExactHeaviside)
+{
+  using InputType = double;
+  using OutputType = double;
+
+  using HeavisideFunctionBaseType = itk::HeavisideStepFunction<InputType, OutputType>;
+
+  auto functionBase0 = HeavisideFunctionBaseType::New();
+
+  std::cout << "GetNameOfClass() = " << functionBase0->GetNameOfClass() << std::endl;
+  functionBase0->Print(std::cout);
+
+  constexpr int minValue{ -20 };
+  constexpr int maxValue{ 20 };
+
+  constexpr InputType incValue{ 0.1 };
+
+  for (int x = minValue; x < maxValue; ++x)
+  {
+    const InputType  ix = x * incValue;
+    const OutputType f = functionBase0->Evaluate(ix);
+    const OutputType df = functionBase0->EvaluateDerivative(ix);
+    std::cout << ix << ' ' << f << ' ' << df << std::endl;
+  }
+}
+
+// From itkAtanRegularizedHeavisideStepFunctionTest1.cxx
+TEST(HeavisideStepFunction, AtanRegularized)
+{
+  using InputType = double;
+  using OutputType = double;
+
+  using HeavisideFunctionBaseType = itk::AtanRegularizedHeavisideStepFunction<InputType, OutputType>;
+
+  auto functionBase0 = HeavisideFunctionBaseType::New();
+
+  std::cout << "GetNameOfClass() = " << functionBase0->GetNameOfClass() << std::endl;
+  functionBase0->Print(std::cout);
+
+  constexpr double epsilon{ -1.0 };
+  EXPECT_THROW(functionBase0->SetEpsilon(epsilon), itk::ExceptionObject);
+
+  constexpr double epsilon0{ 1.0 };
+  constexpr double epsilon1{ 1e-4 };
+
+  EXPECT_EQ(functionBase0->GetEpsilon(), epsilon0);
+
+  functionBase0->SetEpsilon(epsilon1);
+  EXPECT_EQ(functionBase0->GetEpsilon(), epsilon1);
+
+  constexpr double epsilon2{ 0.5 };
+  functionBase0->SetEpsilon(epsilon2);
+
+  constexpr int minValue{ -20 };
+  constexpr int maxValue{ 20 };
+
+  constexpr InputType incValue{ 0.1 };
+
+  for (int x = minValue; x < maxValue; ++x)
+  {
+    const InputType  ix = x * incValue;
+    const OutputType f = functionBase0->Evaluate(ix);
+    const OutputType df = functionBase0->EvaluateDerivative(ix);
+    std::cout << ix << ' ' << f << ' ' << df << std::endl;
+  }
+}
+
+// From itkSinRegularizedHeavisideStepFunctionTest1.cxx
+TEST(HeavisideStepFunction, SinRegularized)
+{
+  using InputType = double;
+  using OutputType = double;
+
+  using HeavisideFunctionBaseType = itk::SinRegularizedHeavisideStepFunction<InputType, OutputType>;
+
+  auto functionBase0 = HeavisideFunctionBaseType::New();
+
+  std::cout << "GetNameOfClass() = " << functionBase0->GetNameOfClass() << std::endl;
+  functionBase0->Print(std::cout);
+
+  constexpr double epsilon{ -1.0 };
+  EXPECT_THROW(functionBase0->SetEpsilon(epsilon), itk::ExceptionObject);
+
+  constexpr double epsilon0{ 1.0 };
+  constexpr double epsilon1{ 1e-4 };
+
+  EXPECT_EQ(functionBase0->GetEpsilon(), epsilon0);
+
+  functionBase0->SetEpsilon(epsilon1);
+  EXPECT_EQ(functionBase0->GetEpsilon(), epsilon1);
+
+  constexpr double epsilon2{ 0.5 };
+  functionBase0->SetEpsilon(epsilon2);
+
+  constexpr int minValue{ -20 };
+  constexpr int maxValue{ 20 };
+
+  constexpr InputType incValue{ 0.1 };
+
+  for (int x = minValue; x < maxValue; ++x)
+  {
+    const InputType  ix = x * incValue;
+    const OutputType f = functionBase0->Evaluate(ix);
+    const OutputType df = functionBase0->EvaluateDerivative(ix);
+    std::cout << ix << ' ' << f << ' ' << df << std::endl;
+  }
+}
diff --git a/Modules/Core/Common/test/itkHeavisideStepFunctionTest1.cxx b/Modules/Core/Common/test/itkHeavisideStepFunctionTest1.cxx
deleted file mode 100644
index edaa5d94820..00000000000
--- a/Modules/Core/Common/test/itkHeavisideStepFunctionTest1.cxx
+++ /dev/null
@@ -1,48 +0,0 @@
-/*=========================================================================
- *
- *  Copyright NumFOCUS
- *
- *  Licensed under the Apache License, Version 2.0 (the "License");
- *  you may not use this file except in compliance with the License.
- *  You may obtain a copy of the License at
- *
- *         https://www.apache.org/licenses/LICENSE-2.0.txt
- *
- *  Unless required by applicable law or agreed to in writing, software
- *  distributed under the License is distributed on an "AS IS" BASIS,
- *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *  See the License for the specific language governing permissions and
- *  limitations under the License.
- *
- *=========================================================================*/
-
-#include "itkHeavisideStepFunction.h"
-
-int
-itkHeavisideStepFunctionTest1(int, char *[])
-{
-  using InputType = double;
-  using OutputType = double;
-
-  using HeavisideFunctionBaseType = itk::HeavisideStepFunction<InputType, OutputType>;
-
-  auto functionBase0 = HeavisideFunctionBaseType::New();
-
-  std::cout << "GetNameOfClass() = " << functionBase0->GetNameOfClass() << std::endl;
-  functionBase0->Print(std::cout);
-
-  constexpr int minValue{ -20 };
-  constexpr int maxValue{ 20 };
-
-  constexpr InputType incValue{ 0.1 };
-
-  for (int x = minValue; x < maxValue; ++x)
-  {
-    const InputType  ix = x * incValue;
-    const OutputType f = functionBase0->Evaluate(ix);
-    const OutputType df = functionBase0->EvaluateDerivative(ix);
-    std::cout << ix << ' ' << f << ' ' << df << std::endl;
-  }
-
-  return EXIT_SUCCESS;
-}
diff --git a/Modules/Core/Common/test/itkSinRegularizedHeavisideStepFunctionTest1.cxx b/Modules/Core/Common/test/itkSinRegularizedHeavisideStepFunctionTest1.cxx
deleted file mode 100644
index 1d56245ad9f..00000000000
--- a/Modules/Core/Common/test/itkSinRegularizedHeavisideStepFunctionTest1.cxx
+++ /dev/null
@@ -1,65 +0,0 @@
-/*=========================================================================
- *
- *  Copyright NumFOCUS
- *
- *  Licensed under the Apache License, Version 2.0 (the "License");
- *  you may not use this file except in compliance with the License.
- *  You may obtain a copy of the License at
- *
- *         https://www.apache.org/licenses/LICENSE-2.0.txt
- *
- *  Unless required by applicable law or agreed to in writing, software
- *  distributed under the License is distributed on an "AS IS" BASIS,
- *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *  See the License for the specific language governing permissions and
- *  limitations under the License.
- *
- *=========================================================================*/
-
-#include "itkSinRegularizedHeavisideStepFunction.h"
-#include "itkTestingMacros.h"
-
-int
-itkSinRegularizedHeavisideStepFunctionTest1(int, char *[])
-{
-  using InputType = double;
-  using OutputType = double;
-
-  using HeavisideFunctionBaseType = itk::SinRegularizedHeavisideStepFunction<InputType, OutputType>;
-
-  auto functionBase0 = HeavisideFunctionBaseType::New();
-
-  std::cout << "GetNameOfClass() = " << functionBase0->GetNameOfClass() << std::endl;
-  functionBase0->Print(std::cout);
-
-  constexpr double epsilon{ -1.0 };
-
-  ITK_TRY_EXPECT_EXCEPTION(functionBase0->SetEpsilon(epsilon));
-
-
-  constexpr double epsilon0{ 1.0 };
-  constexpr double epsilon1{ 1e-4 };
-
-  ITK_TEST_SET_GET_VALUE(epsilon0, functionBase0->GetEpsilon());
-
-  functionBase0->SetEpsilon(epsilon1);
-  ITK_TEST_SET_GET_VALUE(epsilon1, functionBase0->GetEpsilon());
-
-  constexpr double epsilon2{ 0.5 };
-  functionBase0->SetEpsilon(epsilon2);
-
-  constexpr int minValue{ -20 };
-  constexpr int maxValue{ 20 };
-
-  constexpr InputType incValue{ 0.1 };
-
-  for (int x = minValue; x < maxValue; ++x)
-  {
-    const InputType  ix = x * incValue;
-    const OutputType f = functionBase0->Evaluate(ix);
-    const OutputType df = functionBase0->EvaluateDerivative(ix);
-    std::cout << ix << ' ' << f << ' ' << df << std::endl;
-  }
-
-  return EXIT_SUCCESS;
-}