lib/testtools/testtools/tests/test_helpers.py

   1 # Copyright (c) 2010 Jonathan M. Lange. See LICENSE for details.
   2
   3 from testtools import TestCase
   4 from testtools.helpers import (
   5     try_import,
   6     try_imports,
   7     )
   8 from testtools.matchers import (
   9     Equals,
  10     Is,
  11     )
  12
  13
  14 class TestTryImport(TestCase):
  15
  16     def test_doesnt_exist(self):
  17         # try_import('thing', foo) returns foo if 'thing' doesn't exist.
  18         marker = object()
  19         result = try_import('doesntexist', marker)
  20         self.assertThat(result, Is(marker))
  21
  22     def test_None_is_default_alternative(self):
  23         # try_import('thing') returns None if 'thing' doesn't exist.
  24         result = try_import('doesntexist')
  25         self.assertThat(result, Is(None))
  26
  27     def test_existing_module(self):
  28         # try_import('thing', foo) imports 'thing' and returns it if it's a
  29         # module that exists.
  30         result = try_import('os', object())
  31         import os
  32         self.assertThat(result, Is(os))
  33
  34     def test_existing_submodule(self):
  35         # try_import('thing.another', foo) imports 'thing' and returns it if
  36         # it's a module that exists.
  37         result = try_import('os.path', object())
  38         import os
  39         self.assertThat(result, Is(os.path))
  40
  41     def test_nonexistent_submodule(self):
  42         # try_import('thing.another', foo) imports 'thing' and returns foo if
  43         # 'another' doesn't exist.
  44         marker = object()
  45         result = try_import('os.doesntexist', marker)
  46         self.assertThat(result, Is(marker))
  47
  48     def test_object_from_module(self):
  49         # try_import('thing.object') imports 'thing' and returns
  50         # 'thing.object' if 'thing' is a module and 'object' is not.
  51         result = try_import('os.path.join')
  52         import os
  53         self.assertThat(result, Is(os.path.join))
  54
  55
  56 class TestTryImports(TestCase):
  57
  58     def test_doesnt_exist(self):
  59         # try_imports('thing', foo) returns foo if 'thing' doesn't exist.
  60         marker = object()
  61         result = try_imports(['doesntexist'], marker)
  62         self.assertThat(result, Is(marker))
  63
  64     def test_fallback(self):
  65         result = try_imports(['doesntexist', 'os'])
  66         import os
  67         self.assertThat(result, Is(os))
  68
  69     def test_None_is_default_alternative(self):
  70         # try_imports('thing') returns None if 'thing' doesn't exist.
  71         e = self.assertRaises(
  72             ImportError, try_imports, ['doesntexist', 'noreally'])
  73         self.assertThat(
  74             str(e),
  75             Equals("Could not import any of: doesntexist, noreally"))
  76
  77     def test_existing_module(self):
  78         # try_imports('thing', foo) imports 'thing' and returns it if it's a
  79         # module that exists.
  80         result = try_imports(['os'], object())
  81         import os
  82         self.assertThat(result, Is(os))
  83
  84     def test_existing_submodule(self):
  85         # try_imports('thing.another', foo) imports 'thing' and returns it if
  86         # it's a module that exists.
  87         result = try_imports(['os.path'], object())
  88         import os
  89         self.assertThat(result, Is(os.path))
  90
  91     def test_nonexistent_submodule(self):
  92         # try_imports('thing.another', foo) imports 'thing' and returns foo if
  93         # 'another' doesn't exist.
  94         marker = object()
  95         result = try_imports(['os.doesntexist'], marker)
  96         self.assertThat(result, Is(marker))
  97
  98     def test_fallback_submodule(self):
  99         result = try_imports(['os.doesntexist', 'os.path'])
 100         import os
 101         self.assertThat(result, Is(os.path))
 102
 103
 104 def test_suite():
 105     from unittest import TestLoader
 106     return TestLoader().loadTestsFromName(__name__)