Keep unittests DRY, override default_shell in test decorator

- Tests that use the the `per_available_shell` decorator were reporting
  false positives for most cases b/c it appears to have been assumed that
  execute_shell would execute the intended shell when it was actually
  picking up the system shell. If shell had been passed to `execute_shell`
  in most places then this change would not have been needed. After
  observing that most cases appear to depend on overriding the config I
  chose to move the override into the decorator to improve DRY-ness.

Signed-off-by: javrin <jawabiscuit@users.noreply.github.com>

src/rez/tests/test_e2e_shells.py

@@ -7,7 +7,6 @@
 """
 from __future__ import print_function
 
-from rez.config import config
 from rez.shells import create_shell
 from rez.resolved_context import ResolvedContext
 from rez.tests.util import TestBase, TempdirMixin, per_available_shell
@@ -39,10 +38,6 @@ def _create_context(cls, pkgs):
 
     @per_available_shell()
     def test_shell_execution(self, shell):
-        config.override("default_shell", shell)
-        if shell == "gitbash":
-            config.override("enable_path_normalization", True)
-
         sh = create_shell(shell)
         _, _, _, command = sh.startup_capabilities(command=True)
         if command:

src/rez/tests/test_shells.py

@@ -112,10 +112,6 @@ def test_aaa_shell_presence(self):
 
     @per_available_shell()
     def test_no_output(self, shell):
-        config.override("default_shell", shell)
-        if shell == "gitbash":
-            config.override("enable_path_normalization", True)
-
         sh = create_shell(shell)
         _, _, _, command = sh.startup_capabilities(command=True)
         if command:
@@ -310,8 +306,6 @@ def test_rex_code(self, shell):
         """Test that Rex code run in the shell creates the environment variable
         values that we expect.
         """
-        config.override("default_shell", shell)
-
         def _execute_code(func, expected_output):
             loc = inspect.getsourcelines(func)[0][1:]
             code = textwrap.dedent('\n'.join(loc))
@@ -481,8 +475,6 @@ def test_rex_code_alias(self, shell):
         the absolute path to doskey.exe before we modify PATH and continue to
         use the absolute path after the modifications.
         """
-        config.override("default_shell", shell)
-
         def _execute_code(func):
             loc = inspect.getsourcelines(func)[0][1:]
             code = textwrap.dedent('\n'.join(loc))
@@ -509,8 +501,6 @@ def test_alias_command(self, shell):
         This is important for Windows CMD shell because the doskey.exe isn't
         executed yet when the alias is being passed.
         """
-        config.override("default_shell", shell)
-
         def _make_alias(ex):
             ex.alias('hi', 'echo "hi"')
 
@@ -529,8 +519,6 @@ def test_alias_command_with_args(self, shell):
         This is important for Windows CMD shell because the doskey.exe isn't
         executed yet when the alias is being passed.
         """
-        config.override("default_shell", shell)
-
         def _make_alias(ex):
             ex.alias('tell', 'echo')
 

src/rez/tests/test_suites.py

@@ -158,8 +158,6 @@ def test_executable(self, shell):
         ```
 
         """
-        config.override("default_shell", shell)
-
         c_pooh = ResolvedContext(["pooh"])
         s = Suite()
         s.add_context("pooh", c_pooh)

src/rez/tests/util.py

@@ -245,6 +245,21 @@ def decorator(func):
         def wrapper(self, shell=None):
             for shell in shells:
                 print("\ntesting in shell: %s..." % shell)
+                # The default shell if none is configured is the system shell
+                # (bash or cmd ususally), so in order to test the other shells
+                # we need to override the default shell to the one we are
+                # testing to get a accurate results with more complete coverage.
+                #
+                # E.g. create_shell() will use the shell provided by this decorator
+                # but resoved_context.execute_shell() will use the default shell to
+                # execute a command if no shell is passed in.
+                config.override("default_shell", shell)
+
+                # TODO: If & when path normalization is set to True by default,
+                # this should be removed. For now, we need to enable it for
+                # gitbash, because it requires path normalization.
+                if shell == "gitbash":
+                    config.override("enable_path_normalization", True)
 
                 try:
                     func(self, shell=shell)