test lang more thorough

Author: scivision

+stdlib/python_home.m

@@ -6,7 +6,7 @@
   pe = pyenv();
   h = pe.Home;
 catch
-  h = '';
+  h = string.empty;
 end
 
 end

test/TestLang.m

@@ -1,9 +1,8 @@
-classdef (SharedTestFixtures={ matlab.unittest.fixtures.PathFixture(fileparts(fileparts(mfilename('fullpath'))))}, ...
-          TestTags = {'R2019b'}) ...
+classdef (SharedTestFixtures={ matlab.unittest.fixtures.PathFixture(fileparts(fileparts(mfilename('fullpath'))))}) ...
     TestLang < matlab.unittest.TestCase
 
 
-methods (Test, TestTags = {'python'})
+methods (Test, TestTags = {'R2020b', 'python'})
 
 function test_has_python(tc)
 tc.assumeTrue(stdlib.has_python())
@@ -13,26 +12,29 @@ function test_has_python(tc)
 
 function test_python_home(tc)
 tc.assumeTrue(stdlib.has_python(), "Python not available")
-tc.verifyNotEmpty(stdlib.python_home())
+
+r = stdlib.python_home();
+tc.verifyNotEmpty(r)
+tc.verifyClass(r, 'string')
 end
 
 end
 
 
-methods (Test, TestTags = {'dotnet'})
+methods (Test, TestTags = {'R2022b', 'dotnet'})
 
 function test_dotnet_home(tc)
 tc.assumeTrue(stdlib.has_dotnet(), ".NET not available")
 h = stdlib.dotnet_home();
 
-if ~stdlib.matlabOlderThan('R2022b')
-  tc.verifyGreaterThan(strlength(h), 0)
-end
+tc.verifyGreaterThan(strlength(h), 0)
 end
 
+
 function test_dotnet_version(tc)
 tc.assumeTrue(stdlib.has_dotnet())
 v = stdlib.dotnet_version();
+tc.verifyClass(v, 'char')
 tc.verifyTrue(stdlib.version_atleast(v, "4.0"), ".NET version should be greater than 4.0")
 end
 

test_main.m

@@ -1,6 +1,6 @@
 %% TEST_MAIN Run all tests
 %
-% R2021a+ needed for over half of the tests
+% Matlab >= R2020a recommended
 
 function test_main(context, sel)
 arguments
@@ -26,7 +26,16 @@ function test_main(context, sel)
   if e.identifier ~= "MATLAB:InputParser:UnmatchedParameter"
     rethrow(e)
   end
-  suite = testsuite(test_root, 'Tag', tags);
+
+  try
+    suite = testsuite(test_root, 'Tag', tags);
+  catch e
+    if e.identifier == "MATLAB:expectedScalartext"
+      suite = testsuite(test_root, 'Tag', "R2019b");
+    else
+      rethrow(e)
+    end
+  end
 end
 
 % selectIf takes the subset of suite tests that meet "sel" conditions