Merge pull request #32489 from gemmaguest/support_kwargs_in_createChildAlgorithm

Support kwargs in create child algorithm

Framework/PythonInterface/core/inc/MantidPythonInterface/core/Converters/PyNativeTypeExtractor.h

+// Mantid Repository : https://github.com/mantidproject/mantid
+//
+// Copyright © 2021 ISIS Rutherford Appleton Laboratory UKRI,
+//   NScD Oak Ridge National Laboratory, European Spallation Source,
+//   Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
+// SPDX - License - Identifier: GPL - 3.0 +
+#pragma once
+#include "MantidAPI/Workspace.h"
+#include "MantidKernel/Logger.h"
+
+#include <boost/python/extract.hpp>
+#include <boost/python/list.hpp>
+#include <boost/python/object.hpp>
+#include <boost/variant.hpp>
+
+#include <exception>
+#include <string>
+#include <variant>
+#include <vector>
+
+namespace {
+Mantid::Kernel::Logger g_log("Python Type Extractor");
+}
+
+namespace Mantid::PythonInterface {
+
+struct PyNativeTypeExtractor {
+  using PythonOutputT = boost::make_recursive_variant<bool, long, double, std::string, Mantid::API::Workspace_sptr,
+                                                      std::vector<boost::recursive_variant_>>::type;
+
+  static PythonOutputT convert(const boost::python::object &obj) {
+    using namespace boost::python;
+    PyObject *rawptr = obj.ptr();
+    PythonOutputT out;
+
+    if (PyList_Check(rawptr)) {
+      out = handleList(obj);
+    } else if (PyBool_Check(rawptr)) {
+      out = extract<bool>(obj);
+    } else if (PyFloat_Check(rawptr)) {
+      out = extract<double>(obj);
+    } else if (PyLong_Check(rawptr)) {
+      out = extract<long>(obj);
+    } else if (PyUnicode_Check(rawptr)) {
+      out = extract<std::string>(obj);
+    } else if (auto extractor = extract<Mantid::API::Workspace_sptr>(obj); extractor.check()) {
+      out = extractor();
+    } else {
+      throw std::invalid_argument("Unrecognised Python type");
+    }
+    return out;
+  }
+
+private:
+  static PythonOutputT handleList(const boost::python::object &obj) {
+    auto rawptr = obj.ptr();
+    auto n = PyList_Size(rawptr);
+    auto vec = std::vector<PythonOutputT>();
+    vec.reserve(n);
+    for (Py_ssize_t i = 0; i < n; ++i) {
+      vec.emplace_back(convert(obj[i]));
+    }
+    return vec;
+  }
+};
+
+class IPyTypeVisitor : public boost::static_visitor<> {
+public:
+  /**
+   * Dynamically dispatches to overloaded operator depending on the underlying type.
+   * This also handles cases such as std::vector<T>, or nested lists, which will be flattened
+   * by invoking the operator each time for each elem.
+   * This assumes all element in a list matches the first element type found in that list,
+   * where this is not true, the element will be cast to the first element type.
+   *
+   * Note: you will need to include
+   * using Mantid::PythonInterface::IPyTypeVisitor::operator();
+   */
+
+  virtual ~IPyTypeVisitor() = default;
+  virtual void operator()(bool value) const = 0;
+  virtual void operator()(long value) const = 0;
+  virtual void operator()(double value) const = 0;
+  virtual void operator()(std::string) const = 0;
+  virtual void operator()(Mantid::API::Workspace_sptr) const = 0;
+
+  virtual void operator()(std::vector<bool>) const = 0;
+  virtual void operator()(std::vector<long>) const = 0;
+  virtual void operator()(std::vector<double>) const = 0;
+  virtual void operator()(std::vector<std::string>) const = 0;
+
+  void operator()(std::vector<PyNativeTypeExtractor::PythonOutputT> const &values) const {
+    if (values.size() == 0)
+      return;
+    const auto &elemType = values[0].type();
+
+    // We must manually dispatch for container types, as boost will try
+    // to recurse down to scalar values.
+    if (elemType == typeid(bool)) {
+      applyVectorProp<bool>(values);
+    } else if (elemType == typeid(double)) {
+      applyVectorProp<double>(values);
+    } else if (elemType == typeid(long)) {
+      applyVectorProp<long>(values);
+    } else if (elemType == typeid(std::string)) {
+      applyVectorProp<std::string>(values);
+    } else {
+      // Recurse down
+      for (const auto &val : values) {
+        boost::apply_visitor(*this, val);
+      }
+    }
+  }
+
+private:
+  template <typename ScalarT>
+  void applyVectorProp(const std::vector<Mantid::PythonInterface::PyNativeTypeExtractor::PythonOutputT> &values) const {
+    std::vector<ScalarT> propVals;
+    propVals.reserve(values.size());
+
+    // Explicitly copy so we don't have to think about Python lifetimes with refs
+    try {
+
+      std::transform(values.cbegin(), values.cend(), std::back_inserter(propVals),
+                     [](const Mantid::PythonInterface::PyNativeTypeExtractor::PythonOutputT &varadicVal) {
+                       return boost::get<ScalarT>(varadicVal);
+                     });
+    } catch (boost::bad_get &e) {
+      std::string err{
+          "A list with mixed types is unsupported as precision loss can occur trying to determine a common type."
+          " \nOriginal exception: "};
+      // Boost will convert bad_get into runtime_error anyway....
+      throw std::runtime_error(err + e.what());
+    }
+    this->operator()(std::move(propVals));
+  }
+};
+
+} // namespace Mantid::PythonInterface

Framework/PythonInterface/mantid/api/src/Exports/Algorithm.cpp

@@ -17,14 +17,35 @@
 #ifdef _MSC_VER
 #pragma warning(default : 4250)
 #endif
+#include "MantidPythonInterface/core/Converters/PyNativeTypeExtractor.h"
 #include "MantidPythonInterface/core/GetPointer.h"
 
+#include <boost/optional.hpp>
 #include <boost/python/bases.hpp>
 #include <boost/python/class.hpp>
+#include <boost/python/dict.hpp>
 #include <boost/python/exception_translator.hpp>
 #include <boost/python/overloads.hpp>
+// As of boost 1.67 raw_function.hpp tries to pass
+// through size_t types through to make_function
+// which accepts int type, emitting a warning
+#ifdef _MSC_VER
+#pragma warning(push)
+#pragma warning(disable : 4267)
+#endif
+#include <boost/python/raw_function.hpp>
+#ifdef _MSC_VER
+#pragma warning(pop)
+#endif
 #include <boost/python/register_ptr_to_python.hpp>
 #include <boost/python/scope.hpp>
+#include <boost/variant.hpp>
+#include <boost/variant/static_visitor.hpp>
+
+#include <cstddef>
+#include <string>
+#include <variant>
+#include <vector>
 
 using Mantid::API::Algorithm;
 using Mantid::API::DistributedAlgorithm;
@@ -56,6 +77,7 @@ using declarePropertyType3 = void (*)(boost::python::object &, const std::string
 // declarePyAlgProperty(name, defaultValue, direction)
 using declarePropertyType4 = void (*)(boost::python::object &, const std::string &, const boost::python::object &,
                                       const int);
+
 GNU_DIAG_OFF("unused-local-typedef")
 // Ignore -Wconversion warnings coming from boost::python
 // Seen with GCC 7.1.1 and Boost 1.63.0
@@ -64,6 +86,7 @@ GNU_DIAG_OFF("conversion")
 BOOST_PYTHON_FUNCTION_OVERLOADS(declarePropertyType1_Overload, PythonAlgorithm::declarePyAlgProperty, 2, 3)
 BOOST_PYTHON_FUNCTION_OVERLOADS(declarePropertyType2_Overload, PythonAlgorithm::declarePyAlgProperty, 3, 6)
 BOOST_PYTHON_FUNCTION_OVERLOADS(declarePropertyType3_Overload, PythonAlgorithm::declarePyAlgProperty, 4, 5)
+
 GNU_DIAG_ON("conversion")
 GNU_DIAG_ON("unused-local-typedef")
 
@@ -76,6 +99,93 @@ void translateCancel(const Algorithm::CancelException &exc) {
   UNUSED_ARG(exc);
   PyErr_SetString(PyExc_KeyboardInterrupt, "");
 }
+
+template <typename T> boost::optional<T> extractArg(ssize_t index, const tuple &args) {
+  if (index < len(args)) {
+    return boost::optional<T>(extract<T>(args[index]));
+  }
+  return boost::none;
+}
+
+template <typename T> void extractKwargs(const dict &kwargs, const std::string &keyName, boost::optional<T> &out) {
+  if (!kwargs.has_key(keyName)) {
+    return;
+  }
+  if (out != boost::none) {
+    throw std::invalid_argument("Parameter called '" + keyName +
+                                "' was specified twice."
+                                " This must be either positional or a kwarg, but not both.");
+  }
+  out = boost::optional<T>(extract<T>(kwargs.get(keyName)));
+}
+
+class SetPropertyVisitor final : public Mantid::PythonInterface::IPyTypeVisitor {
+public:
+  SetPropertyVisitor(Mantid::API::Algorithm_sptr &alg, std::string const &propName)
+      : m_alg(alg), m_propName(propName) {}
+
+  void operator()(bool value) const override { setProp(value); }
+  void operator()(long value) const override { setProp(static_cast<int>(value)); }
+  void operator()(double value) const override { setProp(value); }
+  void operator()(std::string value) const override { m_alg->setPropertyValue(m_propName, value); }
+  void operator()(Mantid::API::Workspace_sptr ws) const override { m_alg->setProperty(m_propName, std::move(ws)); }
+
+  void operator()(std::vector<bool> value) const override { setProp(value); }
+  void operator()(std::vector<long> value) const override { setProp(value); }
+  void operator()(std::vector<double> value) const override { setProp(value); }
+  void operator()(std::vector<std::string> value) const override { setProp(value); }
+
+  using Mantid::PythonInterface::IPyTypeVisitor::operator();
+
+private:
+  template <typename T> void setProp(const T &val) const { m_alg->setProperty(m_propName, val); }
+
+  Mantid::API::Algorithm_sptr &m_alg;
+  std::string const &m_propName;
+};
+
+// Signature createChildWithProps(self, name, startProgress, endProgress, enableLogging, version, **kwargs)
+object createChildWithProps(tuple args, dict kwargs) {
+  Mantid::API::Algorithm_sptr parentAlg = extract<Mantid::API::Algorithm_sptr>(args[0]);
+  auto name = extractArg<std::string>(1, args);
+  auto startProgress = extractArg<double>(2, args);
+  auto endProgress = extractArg<double>(3, args);
+  auto enableLogging = extractArg<bool>(4, args);
+  auto version = extractArg<int>(5, args);
+
+  const std::array<std::string, 5> reservedNames = {"name", "startProgress", "endProgress", "enableLogging", "version"};
+
+  extractKwargs<std::string>(kwargs, reservedNames[0], name);
+  extractKwargs<double>(kwargs, reservedNames[1], startProgress);
+  extractKwargs<double>(kwargs, reservedNames[2], endProgress);
+  extractKwargs<bool>(kwargs, reservedNames[3], enableLogging);
+  extractKwargs<int>(kwargs, reservedNames[4], version);
+
+  if (!name.is_initialized()) {
+    throw std::invalid_argument("Please specify the algorithm name");
+  }
+  auto childAlg = parentAlg->createChildAlgorithm(name.value(), startProgress.value_or(-1), endProgress.value_or(-1),
+                                                  enableLogging.value_or(true), version.value_or(-1));
+
+  const list keys = kwargs.keys();
+  for (int i = 0; i < len(keys); ++i) {
+    const std::string propName = extract<std::string>(keys[i]);
+
+    if (std::find(reservedNames.cbegin(), reservedNames.cend(), propName) != reservedNames.cend())
+      continue;
+
+    object curArg = kwargs[keys[i]];
+    if (!curArg)
+      continue;
+
+    using Mantid::PythonInterface::PyNativeTypeExtractor;
+    auto nativeObj = PyNativeTypeExtractor::convert(curArg);
+
+    boost::apply_visitor(SetPropertyVisitor(childAlg, propName), nativeObj);
+  }
+  return object(childAlg);
+}
+
 } // namespace
 
 void export_leaf_classes() {
@@ -86,14 +196,11 @@ void export_leaf_classes() {
   // std::shared_ptr<AlgorithmAdapter>
   // See
   // http://wiki.python.org/moin/boost.python/HowTo#ownership_of_C.2B-.2B-_object_extended_in_Python
-
   class_<Algorithm, bases<Mantid::API::IAlgorithm>, std::shared_ptr<PythonAlgorithm>, boost::noncopyable>(
       "Algorithm", "Base class for all algorithms")
       .def("fromString", &Algorithm::fromString, "Initialize the algorithm from a string representation")
       .staticmethod("fromString")
-      .def("createChildAlgorithm", &Algorithm::createChildAlgorithm,
-           (arg("self"), arg("name"), arg("startProgress") = -1.0, arg("endProgress") = -1.0,
-            arg("enableLogging") = true, arg("version") = -1),
+      .def("createChildAlgorithm", raw_function(&createChildWithProps, std::size_t(1)),
            "Creates and intializes a named child algorithm. Output workspaces "
            "are given a dummy name.")
       .def("declareProperty", (declarePropertyType1)&PythonAlgorithm::declarePyAlgProperty,

Framework/PythonInterface/mantid/api/src/FitFunctions/IFunctionAdapter.cpp

@@ -6,10 +6,12 @@
 // SPDX - License - Identifier: GPL - 3.0 +
 #include "MantidPythonInterface/api/FitFunctions/IFunctionAdapter.h"
 #include "MantidPythonInterface/core/CallMethod.h"
+#include "MantidPythonInterface/core/Converters/PyNativeTypeExtractor.h"
 #include "MantidPythonInterface/core/Converters/WrapWithNDArray.h"
 
 #include <boost/python/class.hpp>
 #include <boost/python/list.hpp>
+#include <boost/variant/apply_visitor.hpp>
 #include <utility>
 
 #define PY_ARRAY_UNIQUE_SYMBOL API_ARRAY_API
@@ -25,6 +27,34 @@ using namespace boost::python;
 
 namespace {
 
+class AttrVisitor : Mantid::PythonInterface::IPyTypeVisitor {
+public:
+  AttrVisitor(IFunction::Attribute &attrToUpdate) : m_attr(attrToUpdate) {}
+
+  void operator()(bool value) const override { m_attr.setValue(value); }
+  void operator()(long value) const override { m_attr.setValue(static_cast<int>(value)); }
+  void operator()(double value) const override { m_attr.setValue(value); }
+  void operator()(std::string value) const override { m_attr.setValue(std::move(value)); }
+  void operator()(Mantid::API::Workspace_sptr) const override { throw std::invalid_argument(m_errorMsg); }
+
+  void operator()(std::vector<bool>) const override { throw std::invalid_argument(m_errorMsg); }
+  void operator()(std::vector<long> value) const override {
+    // Previous existing code blindly converted any list type into a list of doubles.
+    // We now have to preserve this behaviour to maintain API compatibility as
+    // setValue only takes std::vector<double>.
+    std::vector<double> doubleVals(value.cbegin(), value.cend());
+    m_attr.setValue(std::move(doubleVals));
+  }
+  void operator()(std::vector<double> value) const override { m_attr.setValue(std::move(value)); }
+  void operator()(std::vector<std::string>) const override { throw std::invalid_argument(m_errorMsg); }
+
+  using Mantid::PythonInterface::IPyTypeVisitor::operator();
+
+private:
+  IFunction::Attribute &m_attr;
+  const std::string m_errorMsg = "Invalid attribute. Allowed types=float,int,str,bool,list(float),list(int)";
+};
+
 /**
  * Create an Attribute from a python value.
  * @param value :: A value python object. Allowed python types:
@@ -33,38 +63,10 @@ namespace {
  */
 IFunction::Attribute createAttributeFromPythonValue(IFunction::Attribute attrToUpdate, const object &value) {
 
-  PyObject *rawptr = value.ptr();
+  using Mantid::PythonInterface::PyNativeTypeExtractor;
+  auto variantObj = PyNativeTypeExtractor::convert(value);
 
-  if (PyBool_Check(rawptr) == 1) {
-    attrToUpdate.setValue(extract<bool>(rawptr)());
-  }
-#if PY_MAJOR_VERSION >= 3
-  else if (PyLong_Check(rawptr) == 1) {
-#else
-  else if (PyInt_Check(rawptr) == 1) {
-#endif
-    attrToUpdate.setValue(extract<int>(rawptr)());
-  } else if (PyFloat_Check(rawptr) == 1) {
-    attrToUpdate.setValue(extract<double>(rawptr)());
-  }
-#if PY_MAJOR_VERSION >= 3
-  else if (PyUnicode_Check(rawptr) == 1) {
-#else
-  else if (PyBytes_Check(rawptr) == 1) {
-#endif
-    attrToUpdate.setValue(extract<std::string>(rawptr)());
-  } else if (PyList_Check(rawptr) == 1) {
-    auto n = PyList_Size(rawptr);
-    std::vector<double> vec;
-    for (Py_ssize_t i = 0; i < n; ++i) {
-      auto v = extract<double>(PyList_GetItem(rawptr, i))();
-      vec.emplace_back(v);
-    }
-    attrToUpdate.setValue(vec);
-  } else {
-    throw std::invalid_argument("Invalid attribute type. Allowed "
-                                "types=float,int,str,bool,list(float)");
-  }
+  boost::apply_visitor(AttrVisitor(attrToUpdate), variantObj);
   return attrToUpdate;
 }
 

Framework/PythonInterface/test/python/mantid/api/AlgorithmTest.py

@@ -7,16 +7,34 @@
 
 import unittest
 import json
-from mantid.api import AlgorithmID, AlgorithmManager, FrameworkManagerImpl
+from mantid.kernel import Direction, FloatArrayProperty, IntArrayProperty, StringArrayProperty, \
+    IntArrayMandatoryValidator, FloatArrayMandatoryValidator, StringArrayMandatoryValidator
+from mantid.simpleapi import CreateSampleWorkspace
+from mantid.api import AlgorithmID, AlgorithmManager, AlgorithmFactory, FrameworkManagerImpl, PythonAlgorithm, Workspace
 from testhelpers import run_algorithm
 
 
-class AlgorithmTest(unittest.TestCase):
+class _ParamTester(PythonAlgorithm):
+
+    def category(self):
+        return "Examples"
+
+    def PyInit(self):
+        self.declareProperty(FloatArrayProperty("FloatInput", FloatArrayMandatoryValidator()))
+        self.declareProperty(IntArrayProperty("IntInput", IntArrayMandatoryValidator()))
+        self.declareProperty(StringArrayProperty("StringInput", StringArrayMandatoryValidator()))
+
+    def PyExec(self):
+        pass
 
+
+class AlgorithmTest(unittest.TestCase):
     _load = None
 
     def setUp(self):
         FrameworkManagerImpl.Instance()
+        self._alg_factory = AlgorithmFactory.Instance()
+        self._alg_factory.subscribe(_ParamTester)
         if self._load is None:
             self.__class__._load = AlgorithmManager.createUnmanaged('Load')
             self._load.initialize()
@@ -48,42 +66,41 @@ class AlgorithmTest(unittest.TestCase):
         self.assertRaises(RuntimeError, alg.execute)
 
     def test_execute_succeeds_with_valid_props(self):
-        data = [1.5,2.5,3.5]
-        alg = run_algorithm('CreateWorkspace',DataX=data,DataY=data,NSpec=1,UnitX='Wavelength',child=True)
+        data = [1.5, 2.5, 3.5]
+        alg = run_algorithm('CreateWorkspace', DataX=data, DataY=data, NSpec=1, UnitX='Wavelength', child=True)
         self.assertEqual(alg.isExecuted(), True)
         self.assertEqual(alg.isRunning(), False)
         self.assertEqual(alg.getProperty('NSpec').value, 1)
         self.assertEqual(type(alg.getProperty('NSpec').value), int)
         self.assertEqual(alg.getProperty('NSpec').name, 'NSpec')
         ws = alg.getProperty('OutputWorkspace').value
-        self.assertTrue(ws.getMemorySize() > 0.0 )
+        self.assertTrue(ws.getMemorySize() > 0.0)
 
         as_str = str(alg)
         self.assertEqual(as_str, '{"name":"CreateWorkspace","properties":{"DataX":[1.5,2.5,3.5],"DataY":[1.5,2.5,3.5],'
-                          '"OutputWorkspace":"UNUSED_NAME_FOR_CHILD","UnitX":"Wavelength"},"version":1}')
+                                 '"OutputWorkspace":"UNUSED_NAME_FOR_CHILD","UnitX":"Wavelength"},"version":1}')
 
     def test_execute_succeeds_with_unicode_props(self):
-        data = [1.5,2.5,3.5]
-        kwargs = {'child':True}
+        data = [1.5, 2.5, 3.5]
+        kwargs = {'child': True}
         unitx = 'Wavelength'
         kwargs['UnitX'] = unitx
 
-
-        alg = run_algorithm('CreateWorkspace',DataX=data,DataY=data,NSpec=1,**kwargs)
+        alg = run_algorithm('CreateWorkspace', DataX=data, DataY=data, NSpec=1, **kwargs)
         self.assertEqual(alg.isExecuted(), True)
         self.assertEqual(alg.isRunning(), False)
         self.assertEqual(alg.getProperty('NSpec').value, 1)
         self.assertEqual(type(alg.getProperty('NSpec').value), int)
         self.assertEqual(alg.getProperty('NSpec').name, 'NSpec')
         ws = alg.getProperty('OutputWorkspace').value
-        self.assertTrue(ws.getMemorySize() > 0.0 )
+        self.assertTrue(ws.getMemorySize() > 0.0)
 
         as_str = str(alg)
         self.assertEqual(as_str, '{"name":"CreateWorkspace","properties":{"DataX":[1.5,2.5,3.5],"DataY":[1.5,2.5,3.5],'
-                          '"OutputWorkspace":"UNUSED_NAME_FOR_CHILD","UnitX":"Wavelength"},"version":1}')
+                                 '"OutputWorkspace":"UNUSED_NAME_FOR_CHILD","UnitX":"Wavelength"},"version":1}')
 
     def test_execute_succeeds_with_unicode_kwargs(self):
-        props = json.loads('{"DryRun":true}') # this is always unicode
+        props = json.loads('{"DryRun":true}')  # this is always unicode
         alg = run_algorithm('Segfault', **props)
 
     def test_getAlgorithmID_returns_AlgorithmID_object(self):
@@ -93,14 +110,14 @@ class AlgorithmTest(unittest.TestCase):
     def test_AlgorithmID_compares_by_value(self):
         alg = AlgorithmManager.createUnmanaged('Load')
         id = alg.getAlgorithmID()
-        self.assertEqual(id, id) # equals itself
+        self.assertEqual(id, id)  # equals itself
         alg2 = AlgorithmManager.createUnmanaged('Load')
         id2 = alg2.getAlgorithmID()
         self.assertNotEqual(id2, id)
 
     def test_cancel_does_nothing_to_executed_algorithm(self):
         data = [1.0]
-        alg = run_algorithm('CreateWorkspace',DataX=data,DataY=data,NSpec=1,UnitX='Wavelength',child=True)
+        alg = run_algorithm('CreateWorkspace', DataX=data, DataY=data, NSpec=1, UnitX='Wavelength', child=True)
         self.assertEqual(alg.isExecuted(), True)
         self.assertEqual(alg.isRunning(), False)
         alg.cancel()
@@ -116,14 +133,151 @@ class AlgorithmTest(unittest.TestCase):
     def test_createChildAlgorithm_respects_keyword_arguments(self):
         parent_alg = AlgorithmManager.createUnmanaged('Load')
         try:
-            child_alg = parent_alg.createChildAlgorithm(name='Rebin',version=1,startProgress=0.5,
-                                                        endProgress=0.9,enableLogging=True)
+            parent_alg.createChildAlgorithm(name='Rebin', version=1, startProgress=0.5,
+                                            endProgress=0.9, enableLogging=True)
         except Exception as exc:
             self.fail("Expected createChildAlgorithm not to throw but it did: %s" % (str(exc)))
 
         # Unknown keyword
-        self.assertRaises(Exception, parent_alg.createChildAlgorithm, name='Rebin',version=1,startProgress=0.5,
-                          endProgress=0.9,enableLogging=True, unknownKW=1)
+        self.assertRaises(Exception, parent_alg.createChildAlgorithm, name='Rebin', version=1, startProgress=0.5,
+                          endProgress=0.9, enableLogging=True, unknownKW=1)
+
+    def test_createChildAlgorithm_with_kwargs(self):
+        parent_alg = AlgorithmManager.createUnmanaged('Load')
+        child_alg = parent_alg.createChildAlgorithm('CreateSampleWorkspace', **{"XUnit": "Wavelength"})
+
+        self.assertTrue(child_alg.isChild())
+        child_alg.execute()
+        ws = child_alg.getProperty("OutputWorkspace").value
+
+        self.assertEqual("Wavelength", ws.getAxis(0).getUnit().unitID())
+
+    def test_createChildAlgorithm_with_named_args(self):
+        parent_alg = AlgorithmManager.createUnmanaged('Load')
+        child_alg = parent_alg.createChildAlgorithm('CreateSampleWorkspace', XUnit="Wavelength")
+
+        self.assertTrue(child_alg.isChild())
+        child_alg.execute()
+        ws = child_alg.getProperty("OutputWorkspace").value
+
+        self.assertEqual("Wavelength", ws.getAxis(0).getUnit().unitID())
+
+    def test_createChildAlgorithm_with_version_and_kwargs(self):
+        parent_alg = AlgorithmManager.createUnmanaged('Load')
+        child_alg = parent_alg.createChildAlgorithm('CreateSampleWorkspace', version=1, **{"XUnit": "Wavelength"})
+
+        self.assertTrue(child_alg.isChild())
+        child_alg.execute()
+        ws = child_alg.getProperty("OutputWorkspace").value
+
+        self.assertEqual("Wavelength", ws.getAxis(0).getUnit().unitID())
+
+    def test_createChildAlgorithm_with_all_args(self):
+        parent_alg = AlgorithmManager.createUnmanaged('Load')
+        child_alg = parent_alg.createChildAlgorithm('CreateSampleWorkspace', startProgress=0.0, endProgress=1.0,
+                                                    enableLogging=False, version=1, **{"XUnit": "Wavelength"})
+
+        self.assertTrue(child_alg.isChild())
+        child_alg.execute()
+        ws = child_alg.getProperty("OutputWorkspace").value
+
+        self.assertEqual("Wavelength", ws.getAxis(0).getUnit().unitID())
+
+    def test_with_workspace_types(self):
+        ws = CreateSampleWorkspace(Function="User Defined",
+                                   UserDefinedFunction="name=LinearBackground, A0=0.3;name=Gaussian, "
+                                                       "PeakCentre=5, Height=10, Sigma=0.7",
+                                   NumBanks=1, BankPixelWidth=1, XMin=0, XMax=10, BinWidth=0.1)
+
+        # Setup the model, here a Gaussian, to fit to data
+        tryCentre = '4'  # A start guess on peak centre
+        sigma = '1'  # A start guess on peak width
+        height = '8'  # A start guess on peak height