diff --git a/CMakeLists.txt b/CMakeLists.txt
index e335dfd575..725171510c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -253,15 +253,14 @@ foreach(test ${TESTS})
       # Preform a parallel test
       add_test(NAME ${TEST_NAME}
         WORKING_DIRECTORY ${TEST_PATH}
-        COMMAND ${PYTHON_EXECUTABLE} ${TEST_NAME} --exe $<TARGET_FILE:openmc>
-        --mpi_exec $ENV{MPI_DIR}/bin/mpiexec)
+        COMMAND ${PYTHON_EXECUTABLE} ${TEST_NAME} --mpi_exec)
 
     else(${MPI_ENABLED})
 
       # Perform a serial test
       add_test(NAME ${TEST_NAME}
         WORKING_DIRECTORY ${TEST_PATH}
-        COMMAND ${PYTHON_EXECUTABLE} ${TEST_NAME} --exe $<TARGET_FILE:openmc>)
+        COMMAND ${PYTHON_EXECUTABLE} ${TEST_NAME})
 
     endif(${MPI_ENABLED})
 
diff --git a/openmc/executor.py b/openmc/executor.py
index d8f52bbec2..0c6a855023 100644
--- a/openmc/executor.py
+++ b/openmc/executor.py
@@ -27,6 +27,9 @@ class Executor(object):
             if line == '' and p.poll() != None:
                 break
 
+        # Return the returncode (integer, zero if no problems encountered)
+        return p.returncode
+
 
     @property
     def working_directory(self):
@@ -50,7 +53,7 @@ class Executor(object):
 
 
     def plot_geometry(self, output=True):
-        self._run_openmc('openmc -p', output)
+        return self._run_openmc('openmc -p', output)
 
 
     def run_simulation(self, particles=None, threads=None,
@@ -80,4 +83,4 @@ class Executor(object):
 
         command = pre_args + 'openmc ' + post_args
 
-        self._run_openmc(command, output)
+        return self._run_openmc(command, output)
diff --git a/tests/test_filter_distribcell/case-3/results_true.dat b/tests/test_filter_distribcell/case-3/results_true.dat
index 65c05d27fd..1378f9cf75 100644
--- a/tests/test_filter_distribcell/case-3/results_true.dat
+++ b/tests/test_filter_distribcell/case-3/results_true.dat
@@ -1 +1 @@
-4ad951a83e28329502830b4161d2b78173768b6d7c8906e5c97aaaa4c3f6e8266762d72fe133a380aa8fae2d2ef85b7cb20be94597b99a72736f9f5c8152555e
\ No newline at end of file
+f5873c6ca03a2c75f5094b7297059285788bb93c450466606914805cdb24fd2664c3872ed42a8c6665a272070ab6b08b0a53b02612bcd993e10329aec2f1d313
\ No newline at end of file
diff --git a/tests/test_filter_distribcell/test_filter_distribcell.py b/tests/test_filter_distribcell/test_filter_distribcell.py
index e860824e81..0513227488 100644
--- a/tests/test_filter_distribcell/test_filter_distribcell.py
+++ b/tests/test_filter_distribcell/test_filter_distribcell.py
@@ -20,15 +20,14 @@ class DistribcellTestHarness(TestHarness):
         try:
             dirs = ('case-1', '../case-2', '../case-3')
             sps = ('statepoint.1.*', 'statepoint.1.*', 'statepoint.3.*')
-            tallies_present = (True, True, False)
+            tallies_out_present = (True, True, False)
             hash_out = (False, False, True)
             for i in range(len(dirs)):
                 os.chdir(dirs[i])
                 self._sp_name = sps[i]
-                self._tallies = tallies_present[i]
 
                 self._run_openmc()
-                self._test_output_created()
+                self._test_output_created(tallies_out_present[i])
                 results = self._get_results(hash_out[i])
                 self._write_results(results)
                 self._compare_results()
@@ -38,6 +37,18 @@ class DistribcellTestHarness(TestHarness):
                 os.chdir(dirs[i])
                 self._cleanup()
 
+    def _test_output_created(self, tallies_out_present):
+        """Make sure statepoint.* and tallies.out have been created."""
+        statepoint = glob.glob(os.path.join(os.getcwd(), self._sp_name))
+        assert len(statepoint) == 1, 'Either multiple or no statepoint files ' \
+             'exist.'
+        assert statepoint[0].endswith('binary') \
+             or statepoint[0].endswith('h5'), \
+             'Statepoint file is not a binary or hdf5 file.'
+        if tallies_out_present:
+            assert os.path.exists(os.path.join(os.getcwd(), 'tallies.out')), \
+                 'Tally output file does not exist.'
+
 
 if __name__ == '__main__':
     harness = DistribcellTestHarness()
diff --git a/tests/test_plot_background/results_true.dat b/tests/test_plot_background/results_true.dat
new file mode 100644
index 0000000000..cea27e38e2
--- /dev/null
+++ b/tests/test_plot_background/results_true.dat
@@ -0,0 +1 @@
+d0a8c3cd2eb2b73430e0fcac2f5249c012ba678d08add40fc43563332e71873977b2271d1e93ba42b3c1298f987f7d01406f60115d2f1c0879d140a11b909598
\ No newline at end of file
diff --git a/tests/test_plot_background/test_plot_background.py b/tests/test_plot_background/test_plot_background.py
index 93cd5da46d..9eec6c0b9f 100644
--- a/tests/test_plot_background/test_plot_background.py
+++ b/tests/test_plot_background/test_plot_background.py
@@ -6,5 +6,5 @@ from testing_harness import PlotTestHarness
 
 
 if __name__ == '__main__':
-    harness = PlotTestHarness('statepoint.10.*', True)
+    harness = PlotTestHarness(('1_plot.ppm', ))
     harness.execute_test()
diff --git a/tests/test_plot_basis/results_true.dat b/tests/test_plot_basis/results_true.dat
new file mode 100644
index 0000000000..90f62cbb05
--- /dev/null
+++ b/tests/test_plot_basis/results_true.dat
@@ -0,0 +1 @@
+8953968071de7c660f8ce07a28b11bb7c37d7150dd2bfd800483e0f76e021d279b100560faf1fb0cd9b8398a1f86b6166ea21f331f265fcf8662b35e70359cad
\ No newline at end of file
diff --git a/tests/test_plot_basis/test_plot_basis.py b/tests/test_plot_basis/test_plot_basis.py
index 93cd5da46d..b1c58979fb 100644
--- a/tests/test_plot_basis/test_plot_basis.py
+++ b/tests/test_plot_basis/test_plot_basis.py
@@ -6,5 +6,5 @@ from testing_harness import PlotTestHarness
 
 
 if __name__ == '__main__':
-    harness = PlotTestHarness('statepoint.10.*', True)
+    harness = PlotTestHarness(('1_plot.ppm', '2_plot.ppm', '3_plot.ppm'))
     harness.execute_test()
diff --git a/tests/test_plot_colspec/results_true.dat b/tests/test_plot_colspec/results_true.dat
new file mode 100644
index 0000000000..0e4eb9a59b
--- /dev/null
+++ b/tests/test_plot_colspec/results_true.dat
@@ -0,0 +1 @@
+32acbbd7b0f777589b108333e4928b6ecd93bc9e553b04cc611da4079ff8738a03dd0667e7e17161708fde86180532f19907272356d23e8a827a736a5b4a697a
\ No newline at end of file
diff --git a/tests/test_plot_colspec/test_plot_colspec.py b/tests/test_plot_colspec/test_plot_colspec.py
index 93cd5da46d..9eec6c0b9f 100644
--- a/tests/test_plot_colspec/test_plot_colspec.py
+++ b/tests/test_plot_colspec/test_plot_colspec.py
@@ -6,5 +6,5 @@ from testing_harness import PlotTestHarness
 
 
 if __name__ == '__main__':
-    harness = PlotTestHarness('statepoint.10.*', True)
+    harness = PlotTestHarness(('1_plot.ppm', ))
     harness.execute_test()
diff --git a/tests/test_plot_mask/results_true.dat b/tests/test_plot_mask/results_true.dat
new file mode 100644
index 0000000000..e1dea0772a
--- /dev/null
+++ b/tests/test_plot_mask/results_true.dat
@@ -0,0 +1 @@
+a32df9c5ab026c40d1b81e303da38cad9a1a6263165087539520d892d0a9cb40193f94f2f5f4d9c94e7e9208121847099bf0c47694d3fc1d01c9e4f57555208b
\ No newline at end of file
diff --git a/tests/test_plot_mask/test_plot_mask.py b/tests/test_plot_mask/test_plot_mask.py
index 93cd5da46d..b1c58979fb 100644
--- a/tests/test_plot_mask/test_plot_mask.py
+++ b/tests/test_plot_mask/test_plot_mask.py
@@ -6,5 +6,5 @@ from testing_harness import PlotTestHarness
 
 
 if __name__ == '__main__':
-    harness = PlotTestHarness('statepoint.10.*', True)
+    harness = PlotTestHarness(('1_plot.ppm', '2_plot.ppm', '3_plot.ppm'))
     harness.execute_test()
diff --git a/tests/test_score_flux_yn/results_true.dat b/tests/test_score_flux_yn/results_true.dat
index 939ff23e3a..9a2d5f3230 100644
--- a/tests/test_score_flux_yn/results_true.dat
+++ b/tests/test_score_flux_yn/results_true.dat
@@ -1 +1,448 @@
-0683f96913bb317c6179de78ecb8fafee5aa12cf5bfc6026c25be0728d691cb9ed388280a57724a961877d4779cd3d382d759ba1c8246cc1015c42a7bc252bd9
\ No newline at end of file
+k-combined:
+1.093844E+00 1.626801E-02
+tally 1:
+3.403102E+01
+2.393236E+02
+1.143060E+01
+2.704386E+01
+5.691243E+01
+6.685581E+02
+2.924945E+01
+1.782032E+02
+9.965051E+00
+2.067319E+01
+4.931805E+01
+5.050490E+02
+tally 2:
+3.403102E+01
+2.393236E+02
+-3.055588E-01
+3.594044E-02
+3.171128E-01
+3.805380E-01
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+-1.621986E-01
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+-4.976706E-01
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+-6.954103E-02
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+-5.205013E-01
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+2.037295E-01
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+-1.290735E-01
+5.069422E-02
+-2.045060E-01
+2.197889E-01
+1.307603E-01
+5.938649E-02
+-3.317004E-01
+1.359233E-01
+-4.347480E-01
+7.528253E-02
+7.685982E-02
+4.559715E-02
+-4.668783E-02
+4.065614E-02
+1.447872E-01
+5.538956E-02
+-2.027337E-01
+7.095051E-02
+-4.673353E-01
+1.235371E-01
+-3.321732E-01
+6.905624E-02
+-3.028859E-01
+3.382353E-02
+-2.320613E-01
+2.845905E-02
+8.038034E-02
+3.466746E-02
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+9.996559E-02
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+-3.473240E-02
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+-1.955516E-01
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+3.530892E-02
+-1.446334E-01
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+-4.072015E-02
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+-4.312304E-01
+2.164291E-01
+2.436515E-01
+8.025128E-02
diff --git a/tests/test_score_flux_yn/test_score_flux_yn.py b/tests/test_score_flux_yn/test_score_flux_yn.py
index 45c433691a..8f3b0785a8 100755
--- a/tests/test_score_flux_yn/test_score_flux_yn.py
+++ b/tests/test_score_flux_yn/test_score_flux_yn.py
@@ -2,9 +2,9 @@
 
 import sys
 sys.path.insert(0, '..')
-from testing_harness import HashedTestHarness
+from testing_harness import TestHarness
 
 
 if __name__ == '__main__':
-    harness = HashedTestHarness('statepoint.10.*', True)
+    harness = TestHarness('statepoint.10.*', True)
     harness.execute_test()
diff --git a/tests/test_source_file/test_source_file.py b/tests/test_source_file/test_source_file.py
index ab8074d469..af998ee339 100644
--- a/tests/test_source_file/test_source_file.py
+++ b/tests/test_source_file/test_source_file.py
@@ -65,19 +65,22 @@ class SourceFileTestHarness(TestHarness):
              'Source file is not a binary or hdf5 file.'
 
     def _run_openmc_restart(self):
+        # Get the number of MPI processes.
+        if self._opts.mpi_exec:
+            mpi_procs = self._opts.mpi_np
+        else:
+            mpi_procs = 1
+
+        # Get the name of the source file.
         source = glob.glob(os.path.join(os.getcwd(), 'source.10.*'))
+
+        # Write the new settings.xml file.
         with open('settings.xml','w') as fh:
             fh.write(settings2.format(source[0].split('.')[-1]))
 
-        if self._opts.mpi_exec != '':
-            proc = Popen([self._opts.mpi_exec, '-np', self._opts.mpi_np,
-                          self._opts.exe, os.getcwd()],
-                         stderr=STDOUT, stdout=PIPE)
-        else:
-            proc = Popen([self._opts.exe, os.getcwd()],
-                         stderr=STDOUT, stdout=PIPE)
-        print(proc.communicate()[0])
-        returncode = proc.returncode
+        # Run OpenMC.
+        executor = Executor()
+        returncode = executor.run_simulation(mpi_procs=mpi_procs)
         assert returncode == 0, 'OpenMC did not exit successfully.'
 
     def _cleanup(self):
diff --git a/tests/test_statepoint_restart/test_statepoint_restart.py b/tests/test_statepoint_restart/test_statepoint_restart.py
index 9d57bd8954..c62eb67df4 100644
--- a/tests/test_statepoint_restart/test_statepoint_restart.py
+++ b/tests/test_statepoint_restart/test_statepoint_restart.py
@@ -15,13 +15,7 @@ class StatepointRestartTestHarness(TestHarness):
             self._write_results(results)
             self._compare_results()
 
-            self._run_openmc_restart1()
-            self._test_output_created()
-            results = self._get_results()
-            self._write_results(results)
-            self._compare_results()
-
-            self._run_openmc_restart2()
+            self._run_openmc_restart()
             self._test_output_created()
             results = self._get_results()
             self._write_results(results)
@@ -29,32 +23,20 @@ class StatepointRestartTestHarness(TestHarness):
         finally:
             self._cleanup()
 
-    def _run_openmc_restart1(self):
+    def _run_openmc_restart(self):
+        # Get the number of MPI processes.
+        if self._opts.mpi_exec:
+            mpi_procs = self._opts.mpi_np
+        else:
+            mpi_procs = 1
+
+        # Get the name of the statepoint file.
         statepoint = glob.glob(os.path.join(os.getcwd(), self._sp_name))
 
-        if self._opts.mpi_exec != '':
-            proc = Popen([self._opts.mpi_exec, '-np', self._opts.mpi_np,
-                          self._opts.exe, '-r', statepoint[0], os.getcwd()],
-                         stderr=STDOUT, stdout=PIPE)
-        else:
-            proc = Popen([self._opts.exe, '-r', statepoint[0], os.getcwd()],
-                         stderr=STDOUT, stdout=PIPE)
-        print(proc.communicate()[0])
-        returncode = proc.returncode
-        assert returncode == 0, 'OpenMC did not exit successfully.'
-
-    def _run_openmc_restart2(self):
-        statepoint = glob.glob(os.path.join(os.getcwd(), self._sp_name))
-
-        if self._opts.mpi_exec != '':
-            proc = Popen([self._opts.mpi_exec, '-np', self._opts.mpi_np,
-                          self._opts.exe, '--restart', statepoint[0],
-                          os.getcwd()], stderr=STDOUT, stdout=PIPE)
-        else:
-            proc = Popen([self._opts.exe, '--restart', statepoint[0],
-                          os.getcwd()], stderr=STDOUT, stdout=PIPE)
-        print(proc.communicate()[0])
-        returncode = proc.returncode
+        # Run OpenMC
+        executor = Executor()
+        returncode = executor.run_simulation(mpi_procs=mpi_procs,
+                                             restart_file=statepoint)
         assert returncode == 0, 'OpenMC did not exit successfully.'
 
 
diff --git a/tests/testing_harness.py b/tests/testing_harness.py
index dc9d71e086..99f2917d80 100644
--- a/tests/testing_harness.py
+++ b/tests/testing_harness.py
@@ -12,6 +12,7 @@ import numpy as np
 
 sys.path.insert(0, '../..')
 from openmc.statepoint import StatePoint
+from openmc.executor import Executor
 import openmc.particle_restart as pr
 
 
@@ -37,24 +38,19 @@ class TestHarness(object):
 
     def _parse_args(self):
         parser = OptionParser()
-        parser.add_option('--mpi_exec', dest='mpi_exec', default='')
+        parser.add_option('--mpi_exec', dest='mpi_exec', action='store_true',
+                          default=False)
         parser.add_option('--mpi_np', dest='mpi_np', default='3')
-        parser.add_option('--exe', dest='exe')
         (self._opts, self._args) = parser.parse_args()
-        if self._opts.exe is None:
-            raise Exception('Must specify OpenMC executable from command line '
-                            'with --exe.')
 
     def _run_openmc(self):
-        if self._opts.mpi_exec != '':
-            proc = Popen([self._opts.mpi_exec, '-np', self._opts.mpi_np,
-                          self._opts.exe, os.getcwd()],
-                         stderr=STDOUT, stdout=PIPE)
+        if self._opts.mpi_exec:
+            mpi_procs = self._opts.mpi_np
         else:
-            proc = Popen([self._opts.exe, os.getcwd()],
-                         stderr=STDOUT, stdout=PIPE)
-        print(proc.communicate()[0])
-        returncode = proc.returncode
+            mpi_procs = 1
+
+        executor = Executor()
+        returncode = executor.run_simulation(mpi_procs=mpi_procs)
         assert returncode == 0, 'OpenMC did not exit successfully.'
 
     def _test_output_created(self):
@@ -132,31 +128,21 @@ class HashedTestHarness(TestHarness):
 
 class PlotTestHarness(TestHarness):
     """Specialized TestHarness for running OpenMC plotting tests.""" 
-    def execute_test(self):
-        """Run OpenMC with the appropriate arguments and check the outputs."""
-        self._parse_args()
-        try:
-            self._run_openmc()
-            self._test_output_created()
-        finally:
-            self._cleanup()
+    def __init__(self, plot_names):
+        self._plot_names = plot_names
+        self._opts = None
+        self._args = None
 
     def _run_openmc(self):
-        if self._opts.mpi_exec != '':
-            proc = Popen([self._opts.mpi_exec, '-np', self._opts.mpi_np,
-                          self._opts.exe, '-p', os.getcwd()],
-                         stderr=STDOUT, stdout=PIPE)
-        else:
-            proc = Popen([self._opts.exe, '-p', os.getcwd()],
-                         stderr=STDOUT, stdout=PIPE)
-        print(proc.communicate()[0])
-        returncode = proc.returncode
+        executor = Executor()
+        returncode = executor.plot_geometry()
         assert returncode == 0, 'OpenMC did not exit successfully.'
 
     def _test_output_created(self):
         """Make sure *.ppm has been created."""
-        assert os.path.exists(os.path.join(os.getcwd(), '1_plot.ppm')), \
-             'Plot output file does not exist.'
+        for fname in self._plot_names:
+            assert os.path.exists(os.path.join(os.getcwd(), fname)), \
+                 'Plot output file does not exist.'
 
     def _cleanup(self):
         TestHarness._cleanup(self)
@@ -165,6 +151,24 @@ class PlotTestHarness(TestHarness):
             if os.path.exists(f):
                 os.remove(f)
 
+    def _get_results(self):
+        """Return a string hash of the plot files."""
+        # Find the plot files.
+        plot_files = glob.glob(os.path.join(os.getcwd(), '*.ppm'))
+
+        # Read the plot files.
+        outstr = bytes()
+        for fname in plot_files:
+            with open(fname, 'rb') as fh:
+                outstr += fh.read()
+
+        # Hash the information and return.
+        sha512 = hashlib.sha512()
+        sha512.update(outstr)
+        outstr = sha512.hexdigest()
+
+        return outstr
+
 
 class CMFDTestHarness(TestHarness):
     """Specialized TestHarness for running OpenMC CMFD tests."""