feat(out): detect non-UTF8 environment and adapt output

This test has to be run in docker, because the host system
may only have unicode locales available, and adding a new one
requires root access.

tests/test_regression.py

@@ -45,3 +45,25 @@ def test_p4_multiple_spaces_in_mappings(perforce_workspace, tmpdir):
     environment.settings.PerforceMainVcs.force_clean = True
     environment.settings.PerforceWithMappings.mappings = [f"{perforce_workspace.depot}   /..."]
     assert not __main__.run(environment.settings)
+
+
+def test_non_utf8_environment(docker_main):
+    # POSIX has no 'UTF-8' in it's name, but supports Unicode
+    output = docker_main.run("""
+from universum.configuration_support import Variations
+
+configs = Variations([dict(name="Test configuration", command=["ls", "-la"])])
+""", vcs_type="none", environment=['LANG=POSIX', 'LC_ALL=POSIX'])
+    assert "\u2514" in output
+
+    # 'en_US', unlike 'en_US.UTF-8', is latin-1
+    docker_main.clean_artifacts()
+    docker_main.environment.assert_successful_execution('apt install -y locales')
+    docker_main.environment.assert_successful_execution('locale-gen --purge en_US')
+    docker_main.environment.assert_successful_execution('update-locale LANG=en_US')
+    output = docker_main.run("""
+from universum.configuration_support import Variations
+
+configs = Variations([dict(name="Test configuration", command=["ls", "-la"])])
+""", vcs_type="none", environment=['LANG=en_US', 'LC_ALL=en_US'])
+    assert "\u2514" not in output

universum/modules/output/terminal_based_output.py

@@ -1,3 +1,4 @@
+import locale
 import sys
 
 from six.moves import range
@@ -28,6 +29,7 @@ class TerminalBasedOutput(BaseOutput):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.block_level = 0
+        self.unicode_acceptable = (locale.getpreferredencoding() == "UTF-8")
 
     def indent(self):
         for x in range(0, self.block_level):
@@ -48,11 +50,15 @@ def open_block(self, num_str, name):
     def close_block(self, num_str, name, status):
         self.block_level -= 1
         self.indent()
+        if self.unicode_acceptable:
+            block_end = " \u2514 "
+        else:
+            block_end = " | "
 
         if status == "Failed":
-            stdout(self.block_level * "  ", " \u2514 ", Colors.red, "[Failed]", Colors.reset)
+            stdout(self.block_level * "  ", block_end, Colors.red, "[Failed]", Colors.reset)
         else:
-            stdout(self.block_level * "  ", " \u2514 ", Colors.green, "[Success]", Colors.reset)
+            stdout(self.block_level * "  ", block_end, Colors.green, "[Success]", Colors.reset)
         self.indent()
         stdout()