Use the minimal Python interface for tests when others are not built

If no full or minimal Python interface is being built, copy the minimal
interface into the build directory and use the sys.executable to run it,
so the tests that require CTML or CTI conversion can run.

SConstruct

@@ -112,6 +112,7 @@ if 'clean' in COMMAND_LINE_TARGETS:
 if 'test-clean' in COMMAND_LINE_TARGETS:
     removeDirectory('build/test')
     removeDirectory('test/work')
+    removeDirectory('build/python_minimal')
 
 # ******************************************************
 # *** Set system-dependent defaults for some options ***
@@ -1789,6 +1790,21 @@ if any(target.startswith('test') for target in COMMAND_LINE_TARGETS):
     env['testNames'] = []
     env['test_results'] = env.Command('test_results', [], testResults.printReport)
 
+    if env['python2_package'] == 'none' and env['python3_package'] == 'none':
+        # copy scripts from the full Cython module
+        test_py_int = env.Command('#build/python_minimal/cantera/__init__.py',
+                                  '#interfaces/python_minimal/cantera/__init__.py',
+                                  Copy('$TARGET', '$SOURCE'))
+        for script in ['ctml_writer', 'ck2cti']:
+            s = env.Command('#build/python_minimal/cantera/{}.py'.format(script),
+                            '#interfaces/cython/cantera/{}.py'.format(script),
+                            Copy('$TARGET', '$SOURCE'))
+            env.Depends(test_py_int, s)
+
+        env.Depends(env['test_results'], test_py_int)
+
+        env['python_cmd'] = sys.executable
+
     # Tests written using the gtest framework, the Python unittest module,
     # or the Matlab xunit package.
     VariantDir('build/test', 'test', duplicate=0)

test/SConscript

@@ -209,14 +209,15 @@ def addMatlabTest(script, testName, dependencies=None, env_vars=()):
 
     return run_program
 
-if localenv['python_package'] in ('full', 'minimal'):
+if localenv['python2_package'] in ('full', 'minimal'):
     python_env_vars = {'PYTHONPATH': localenv['pythonpath_build2'],
-                       'PYTHON_CMD': localenv.subst('$python_cmd')}
-elif localenv['python3_package'] == 'y':
+                       'PYTHON_CMD': localenv.subst('$python2_cmd')}
+elif localenv['python3_package'] in ('full', 'minimal'):
     python_env_vars = {'PYTHONPATH': localenv['pythonpath_build3'],
                        'PYTHON_CMD': localenv.subst('$python3_cmd')}
 else:
-    python_env_vars = {} # Tests calling ck2cti or ctml_writer will fail
+    python_env_vars = {'PYTHONPATH': '../../build/python_minimal',
+                       'PYTHON_CMD': localenv.subst('$python_cmd')}
 
 
 # Instantiate tests

test_problems/SConscript

@@ -19,16 +19,18 @@ if localenv['OS'] == 'Linux':
 else:
     cantera_libs = localenv['cantera_libs']
 
-if localenv['python_package'] in ('full', 'minimal'):
+if localenv['python2_package'] in ('full', 'minimal'):
     localenv['ENV']['PYTHONPATH'] = localenv['pythonpath_build2']
-    localenv['ENV']['PYTHON_CMD'] = localenv.subst('$python_cmd')
+    localenv['ENV']['PYTHON_CMD'] = localenv.subst('$python2_cmd')
     haveConverters = True
-elif localenv['python3_package'] == 'y':
+elif localenv['python3_package'] in ('full', 'minimal'):
     localenv['ENV']['PYTHONPATH'] = localenv['pythonpath_build3']
     localenv['ENV']['PYTHON_CMD'] = localenv.subst('$python3_cmd')
     haveConverters = True
 else:
-    haveConverters = False
+    localenv['ENV']['PYTHONPATH'] = '../../build/python_minimal'
+    localenv['ENV']['PYTHON_CMD'] = localenv.subst('$python_cmd')
+    haveConverters = True
 
 localenv['ENV']['CANTERA_DATA'] = pjoin(os.getcwd(), '..', 'build', 'data')