diff --git a/CMakeModules/CalamaresAddModuleSubdirectory.cmake b/CMakeModules/CalamaresAddModuleSubdirectory.cmake
index 7c0159ac0..53b952b54 100644
--- a/CMakeModules/CalamaresAddModuleSubdirectory.cmake
+++ b/CMakeModules/CalamaresAddModuleSubdirectory.cmake
@@ -64,22 +64,31 @@ function( calamares_add_module_subdirectory )
         set( MODULE_DESTINATION ${MODULES_DIR}/${SUBDIRECTORY} )
 
         # Read module.desc, check that the interface type is supported.
+        #
+        # _mod_enabled boolean if the module should be built (only if the interface is supported)
+        # _mod_reason is a human-readable explanation why it isn't built
+        # _mod_testing boolean if the module should be added to the loadmodule tests
         file(STRINGS "${_mod_dir}/module.desc" MODULE_INTERFACE REGEX "^interface")
         if ( MODULE_INTERFACE MATCHES "pythonqt" )
             set( _mod_enabled ${WITH_PYTHONQT} )
             set( _mod_reason "No PythonQt support" )
+            set( _mod_testing OFF )
         elseif ( MODULE_INTERFACE MATCHES "python" )
             set( _mod_enabled ${WITH_PYTHON} )
             set( _mod_reason "No Python support" )
+            set( _mod_testing ON )  # Will check syntax and imports, at least
         elseif ( MODULE_INTERFACE MATCHES "qtplugin" )
             set( _mod_enabled OFF )
             set( _mod_reason "C++ modules must have a CMakeLists.txt instead" )
+            set( _mod_testing OFF )
         elseif ( MODULE_INTERFACE MATCHES "process" )
             set( _mod_enabled ON )
             set( _mod_reason "" )
+            set( _mod_testing OFF )
         else()
             set( _mod_enabled OFF )
             set( _mod_reason "Unknown module interface '${MODULE_INTERFACE}'" )
+            set( _mod_testing OFF )
         endif()
 
         if ( _mod_enabled )
@@ -153,11 +162,11 @@ function( calamares_add_module_subdirectory )
     # may try to do things to the running system. Needs work to make that a
     # safe thing to do.
     #
-    # if ( BUILD_TESTING )
-    #     add_test(
-    #         NAME load-${SUBDIRECTORY}
-    #         COMMAND loadmodule ${SUBDIRECTORY}
-    #         WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
-    #         )
-    # endif()
+    if ( BUILD_TESTING AND _mod_enabled AND _mod_testing )
+        add_test(
+            NAME load-${SUBDIRECTORY}
+            COMMAND loadmodule ${SUBDIRECTORY}
+            WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
+            )
+    endif()
 endfunction()
diff --git a/src/calamares/testmain.cpp b/src/calamares/testmain.cpp
index 195701024..982a9b4c2 100644
--- a/src/calamares/testmain.cpp
+++ b/src/calamares/testmain.cpp
@@ -227,7 +227,8 @@ main( int argc, char* argv[] )
             cError() << "Job #" << count << "failed"
                 << TR( "summary", r.message() )
                 << TR( "details", r.details() );
-            ++failure_count;
+            if ( r.errorCode() > 0 )
+                ++failure_count;
         }
         ++count;
     }
diff --git a/src/libcalamares/Job.cpp b/src/libcalamares/Job.cpp
index b5d626854..d2118451f 100644
--- a/src/libcalamares/Job.cpp
+++ b/src/libcalamares/Job.cpp
@@ -21,16 +21,16 @@
 namespace Calamares
 {
 
-JobResult::JobResult( JobResult&& rhs ) :
-      m_ok( rhs.m_ok )
-    , m_message( std::move( rhs.m_message ) )
+JobResult::JobResult( JobResult&& rhs )
+    : m_message( std::move( rhs.m_message ) )
     , m_details( std::move( rhs.m_details ) )
+    , m_number( rhs.m_number )
 {
 }
 
 JobResult::operator bool() const
 {
-    return m_ok;
+    return m_number == 0;
 }
 
 
@@ -64,21 +64,26 @@ JobResult::setDetails( const QString& details )
 JobResult
 JobResult::ok()
 {
-    return JobResult( true, QString(), QString() );
+    return JobResult( QString(), QString(), NoError );
 }
 
 
 JobResult
 JobResult::error( const QString& message, const QString& details )
 {
-    return JobResult( false, message, details );
+    return JobResult( message, details, GenericError );
 }
 
+JobResult
+JobResult::internalError( const QString& message, const QString& details, int number )
+{
+    return JobResult( message, details, number ? number : GenericError );
+}
 
-JobResult::JobResult( bool ok, const QString& message, const QString& details )
-    : m_ok( ok )
-    , m_message( message )
+JobResult::JobResult( const QString& message, const QString& details, int number )
+    : m_message( message )
     , m_details( details )
+    , m_number( number )
 {}
 
 
diff --git a/src/libcalamares/Job.h b/src/libcalamares/Job.h
index 040ead6ad..04b4560a4 100644
--- a/src/libcalamares/Job.h
+++ b/src/libcalamares/Job.h
@@ -29,6 +29,20 @@ namespace Calamares {
 class DLLEXPORT JobResult
 {
 public:
+    /** @brief Distinguish classes of errors
+     *
+     * All "ok result" have errorCode 0 (NoError).
+     * Errors returned from job execution have values < 0.
+     * Errors before job execution, or not returned by the job execution
+     * itself, have values > 0.
+     */
+    enum
+    {
+        NoError = 0,
+        GenericError = -1,
+        PythonUncaughtException = 1
+    } ;
+
     JobResult( const JobResult& rhs ) = delete;
     JobResult( JobResult&& rhs );
 
@@ -42,17 +56,22 @@ public:
     virtual QString details() const;
     virtual void setDetails( const QString& details );
 
-    static JobResult ok();
+    int errorCode() const { return m_number; }
 
+    /// @brief an "ok status" result
+    static JobResult ok();
+    /// @brief an "error" result resulting from the execution of the job
     static JobResult error( const QString& message, const QString& details = QString() );
+    /// @brief an "internal error" meaning the job itself has a problem (usually for python)
+    static JobResult internalError( const QString&, const QString& details, int errorCode );
 
 protected:
-    explicit JobResult( bool ok, const QString& message, const QString& details );
+    explicit JobResult( const QString& message, const QString& details, int errorCode );
 
 private:
-    bool m_ok;
     QString m_message;
     QString m_details;
+    int m_number;
 };
 
 class DLLEXPORT Job : public QObject
diff --git a/src/libcalamares/PythonJob.cpp b/src/libcalamares/PythonJob.cpp
index 6e8323e49..32792e737 100644
--- a/src/libcalamares/PythonJob.cpp
+++ b/src/libcalamares/PythonJob.cpp
@@ -373,8 +373,10 @@ PythonJob::exec()
         }
         bp::handle_exception();
         PyErr_Clear();
-        return JobResult::error( tr( "Boost.Python error in job \"%1\"." ).arg( prettyName() ),
-                                 msg );
+        return JobResult::internalError(
+                    tr( "Boost.Python error in job \"%1\"." ).arg( prettyName() ),
+                    msg,
+                    JobResult::PythonUncaughtException );
     }
 }
 
diff --git a/src/libcalamaresui/viewpages/PythonQtJob.h b/src/libcalamaresui/viewpages/PythonQtJob.h
index f356e85cc..2b50c0ded 100644
--- a/src/libcalamaresui/viewpages/PythonQtJob.h
+++ b/src/libcalamaresui/viewpages/PythonQtJob.h
@@ -36,7 +36,7 @@ public:
                                 const QString& message,
                                 const QString& details )
         : QObject( nullptr )
-        , Calamares::JobResult( ok, message, details )
+        , Calamares::JobResult( message, details, ok ? 0 : Calamares::JobResult::GenericError )
     {}
 };
 
diff --git a/src/modules/fstab/main.py b/src/modules/fstab/main.py
index 1aea5523e..abbd3d524 100644
--- a/src/modules/fstab/main.py
+++ b/src/modules/fstab/main.py
@@ -306,6 +306,16 @@ def run():
     conf = libcalamares.job.configuration
     partitions = global_storage.value("partitions")
     root_mount_point = global_storage.value("rootMountPoint")
+
+    if not partitions:
+        libcalamares.utils.warning("partitions is empty, {!s}".format(partitions))
+        return (_("Configuration Error"),
+                _("No partitions are defined for <pre>{!s}</pre> to use." ).format("fstab"))
+    if not root_mount_point:
+        libcalamares.utils.warning("rootMountPoint is empty, {!s}".format(root_mount_point))
+        return (_("Configuration Error"),
+                _("No root mount point is given for <pre>{!s}</pre> to use." ).format("fstab"))
+
     mount_options = conf["mountOptions"]
     ssd_extra_mount_options = conf.get("ssdExtraMountOptions", {})
     crypttab_options = conf.get("crypttabOptions", "luks")
diff --git a/src/modules/initcpio/main.py b/src/modules/initcpio/main.py
index 20d841de5..796f68721 100644
--- a/src/modules/initcpio/main.py
+++ b/src/modules/initcpio/main.py
@@ -32,18 +32,19 @@ _ = gettext.translation("calamares-python",
 def pretty_name():
     return _("Creating initramfs with mkinitcpio.")
 
-
-def run_mkinitcpio():
-    """ Runs mkinitcpio with given kernel profile """
-    kernel = libcalamares.job.configuration['kernel']
-    check_target_env_call(['mkinitcpio', '-p', kernel])
-
-
 def run():
     """ Calls routine to create kernel initramfs image.
 
     :return:
     """
-    run_mkinitcpio()
+    from subprocess import CalledProcessError
+
+    kernel = libcalamares.job.configuration['kernel']
+    try:
+        check_target_env_call(['mkinitcpio', '-p', kernel])
+    except CalledProcessError as e:
+        libcalamares.utils.warning(str(e))
+        return ( _( "Process Failed" ),
+                 _( "Process <pre>mkinitcpio</pre> failed with error code {!s}. The command was <pre>{!s}</pre>." ).format( e.returncode, e.cmd ) )
 
     return None
diff --git a/src/modules/initcpiocfg/main.py b/src/modules/initcpiocfg/main.py
index 2207816d9..166cccf44 100644
--- a/src/modules/initcpiocfg/main.py
+++ b/src/modules/initcpiocfg/main.py
@@ -181,6 +181,16 @@ def run():
     """
     partitions = libcalamares.globalstorage.value("partitions")
     root_mount_point = libcalamares.globalstorage.value("rootMountPoint")
+
+    if not partitions:
+        libcalamares.utils.warning("partitions is empty, {!s}".format(partitions))
+        return (_("Configuration Error"),
+                _("No partitions are defined for <pre>{!s}</pre> to use." ).format("initcpiocfg"))
+    if not root_mount_point:
+        libcalamares.utils.warning("rootMountPoint is empty, {!s}".format(root_mount_point))
+        return (_("Configuration Error"),
+                _("No root mount point is given for <pre>{!s}</pre> to use." ).format("initcpiocfg"))
+
     modify_mkinitcpio_conf(partitions, root_mount_point)
 
     return None
diff --git a/src/modules/initramfscfg/main.py b/src/modules/initramfscfg/main.py
index b62e4e5f7..52d512567 100644
--- a/src/modules/initramfscfg/main.py
+++ b/src/modules/initramfscfg/main.py
@@ -88,6 +88,16 @@ def run():
     """
     partitions = libcalamares.globalstorage.value("partitions")
     root_mount_point = libcalamares.globalstorage.value("rootMountPoint")
+
+    if not partitions:
+        libcalamares.utils.warning("partitions is empty, {!s}".format(partitions))
+        return (_("Configuration Error"),
+                _("No partitions are defined for <pre>{!s}</pre> to use." ).format("initramfscfg"))
+    if not root_mount_point:
+        libcalamares.utils.warning("rootMountPoint is empty, {!s}".format(root_mount_point))
+        return (_("Configuration Error"),
+                _("No root mount point is given for <pre>{!s}</pre> to use." ).format("initramfscfg"))
+
     copy_initramfs_hooks(partitions, root_mount_point)
 
     return None
diff --git a/src/modules/localecfg/main.py b/src/modules/localecfg/main.py
index 09e700409..9e50fb448 100644
--- a/src/modules/localecfg/main.py
+++ b/src/modules/localecfg/main.py
@@ -138,6 +138,12 @@ def run():
         }
 
     install_path = libcalamares.globalstorage.value("rootMountPoint")
+
+    if install_path is None:
+        libcalamares.utils.warning("rootMountPoint is empty, {!s}".format(install_path))
+        return (_("Configuration Error"),
+                _("No root mount point is given for <pre>{!s}</pre> to use." ).format("localecfg"))
+
     target_locale_gen = "{!s}/etc/locale.gen".format(install_path)
     target_locale_gen_bak = target_locale_gen + ".bak"
     target_locale_conf_path = "{!s}/etc/locale.conf".format(install_path)
diff --git a/src/modules/luksbootkeyfile/main.py b/src/modules/luksbootkeyfile/main.py
index 0c025ca31..fb0146cf8 100644
--- a/src/modules/luksbootkeyfile/main.py
+++ b/src/modules/luksbootkeyfile/main.py
@@ -46,6 +46,11 @@ def run():
 
     partitions = libcalamares.globalstorage.value("partitions")
 
+    if not partitions:
+        libcalamares.utils.warning("partitions is empty, {!s}".format(partitions))
+        return (_("Configuration Error"),
+                _("No partitions are defined for <pre>{!s}</pre> to use." ).format("luksbootkey"))
+
     luks_root_device = ""
     luks_root_passphrase = ""
 
diff --git a/src/modules/luksopenswaphookcfg/main.py b/src/modules/luksopenswaphookcfg/main.py
index e32fbbbfd..a30ae999b 100644
--- a/src/modules/luksopenswaphookcfg/main.py
+++ b/src/modules/luksopenswaphookcfg/main.py
@@ -90,6 +90,15 @@ def run():
     openswap_conf_path = libcalamares.job.configuration["configFilePath"]
     partitions = libcalamares.globalstorage.value("partitions")
 
+    if not partitions:
+        libcalamares.utils.warning("partitions is empty, {!s}".format(partitions))
+        return (_("Configuration Error"),
+                _("No partitions are defined for <pre>{!s}</pre> to use." ).format("luksopenswaphookcfg"))
+    if not root_mount_point:
+        libcalamares.utils.warning("rootMountPoint is empty, {!s}".format(root_mount_point))
+        return (_("Configuration Error"),
+                _("No root mount point is given for <pre>{!s}</pre> to use." ).format("luksopenswaphookcfg"))
+
     openswap_conf_path = openswap_conf_path.lstrip('/')
 
     return write_openswap_conf(partitions, root_mount_point, openswap_conf_path)
diff --git a/src/modules/machineid/main.py b/src/modules/machineid/main.py
index 092fc7196..cde47cfd9 100644
--- a/src/modules/machineid/main.py
+++ b/src/modules/machineid/main.py
@@ -43,6 +43,12 @@ def run():
     :return:
     """
     root_mount_point = libcalamares.globalstorage.value("rootMountPoint")
+
+    if root_mount_point is None:
+        libcalamares.utils.warning("rootMountPoint is empty, {!s}".format(root_mount_point))
+        return (_("Configuration Error"),
+                _("No root mount point is given for <pre>{!s}</pre> to use." ).format("machineid"))
+
     enable_systemd = libcalamares.job.configuration["systemd"]
     enable_dbus = libcalamares.job.configuration["dbus"]
     enable_symlink = libcalamares.job.configuration["symlink"]
diff --git a/src/modules/mount/main.py b/src/modules/mount/main.py
index 50b74b844..aab3568d1 100644
--- a/src/modules/mount/main.py
+++ b/src/modules/mount/main.py
@@ -133,9 +133,15 @@ def run():
 
     :return:
     """
-    root_mount_point = tempfile.mkdtemp(prefix="calamares-root-")
     partitions = libcalamares.globalstorage.value("partitions")
 
+    if not partitions:
+        libcalamares.utils.warning("partitions is empty, {!s}".format(partitions))
+        return (_("Configuration Error"),
+                _("No partitions are defined for <pre>{!s}</pre> to use." ).format("mount"))
+
+    root_mount_point = tempfile.mkdtemp(prefix="calamares-root-")
+
     # Guard against missing keys (generally a sign that the config file is bad)
     extra_mounts = libcalamares.job.configuration.get("extraMounts") or []
     extra_mounts_efi = libcalamares.job.configuration.get("extraMountsEfi") or []
diff --git a/src/modules/networkcfg/main.py b/src/modules/networkcfg/main.py
index 5509be205..00a264f53 100644
--- a/src/modules/networkcfg/main.py
+++ b/src/modules/networkcfg/main.py
@@ -41,8 +41,13 @@ def run():
     """
     Setup network configuration
     """
-
     root_mount_point = libcalamares.globalstorage.value("rootMountPoint")
+
+    if root_mount_point is None:
+        libcalamares.utils.warning("rootMountPoint is empty, {!s}".format(root_mount_point))
+        return (_("Configuration Error"),
+                _("No root mount point is given for <pre>{!s}</pre> to use." ).format("networkcfg"))
+
     source_nm = "/etc/NetworkManager/system-connections/"
     target_nm = os.path.join(
         root_mount_point, "etc/NetworkManager/system-connections/"
diff --git a/src/modules/openrcdmcryptcfg/main.py b/src/modules/openrcdmcryptcfg/main.py
index 20b306442..0362b421b 100644
--- a/src/modules/openrcdmcryptcfg/main.py
+++ b/src/modules/openrcdmcryptcfg/main.py
@@ -73,6 +73,15 @@ def run():
     dmcrypt_conf_path = libcalamares.job.configuration["configFilePath"]
     partitions = libcalamares.globalstorage.value("partitions")
 
+    if not partitions:
+        libcalamares.utils.warning("partitions is empty, {!s}".format(partitions))
+        return (_("Configuration Error"),
+                _("No partitions are defined for <pre>{!s}</pre> to use." ).format("openrcdmcryptcfg"))
+    if not root_mount_point:
+        libcalamares.utils.warning("rootMountPoint is empty, {!s}".format(root_mount_point))
+        return (_("Configuration Error"),
+                _("No root mount point is given for <pre>{!s}</pre> to use." ).format("openrcdmcryptcfg"))
+
     dmcrypt_conf_path = dmcrypt_conf_path.lstrip('/')
 
     return write_dmcrypt_conf(partitions, root_mount_point, dmcrypt_conf_path)
diff --git a/src/modules/rawfs/main.py b/src/modules/rawfs/main.py
index acf901a0c..af8a8198c 100644
--- a/src/modules/rawfs/main.py
+++ b/src/modules/rawfs/main.py
@@ -166,6 +166,11 @@ def run():
     filesystems = list()
     partitions = libcalamares.globalstorage.value("partitions")
 
+    if not partitions:
+        libcalamares.utils.warning("partitions is empty, {!s}".format(partitions))
+        return (_("Configuration Error"),
+                _("No partitions are defined for <pre>{!s}</pre> to use." ).format("rawfs"))
+
     for partition in partitions:
         if partition["mountPoint"]:
             for src in libcalamares.job.configuration["targets"]: