fix some tests, make them crossplatform

tests/test_api.py

@@ -4,6 +4,7 @@
 import os
 import shutil
 from contextlib import suppress
+from pathlib import Path
 
 import log
 import pytest
@@ -74,7 +75,7 @@ def config():
         os.makedirs(TMP)
     os.chdir(TMP)
 
-    os.system("touch .git")
+    Path(".git").touch()
     config = Config(root=TMP)
     config.datafile.text = CONFIG
     config.datafile.load()
@@ -258,20 +259,20 @@ def it_should_create_links(config_with_link):
             expect(os.listdir()).contains("my_link")
 
         def it_should_not_overwrite_files(config_with_link):
-            os.system("touch my_link")
+            Path("my_link").touch()
 
             with pytest.raises(RuntimeError):
                 gitman.install(depth=1)
 
         def it_should_not_overwrite_non_empty_directories(config_with_link):
-            os.system("mkdir my_link")
-            os.system("touch mylink/my_link")
+            os.mkdir("my_link")
+            Path("my_link/my_link").touch()
 
             with pytest.raises(RuntimeError):
                 gitman.install(depth=1)
 
         def it_overwrites_files_with_force(config_with_link):
-            os.system("touch my_link")
+            Path("my_link").touch()
 
             expect(gitman.install(depth=1, force=True)) == True
 
@@ -307,20 +308,20 @@ def it_should_create_links(config_with_links):
             expect(os.listdir()).contains("gmd_4")
 
         def it_should_not_overwrite_files(config_with_links):
-            os.system("touch gmd_3")
+            Path("gmd_3").touch()
 
             with pytest.raises(RuntimeError):
                 gitman.install(depth=1)
 
         def it_should_not_overwrite_non_empty_directories(config_with_links):
-            os.system("mkdir gmd_3")
-            os.system("touch gmd_3/my_link")
+            os.mkdir("gmd_3")
+            Path("gmd_3/my_link").touch()
 
             with pytest.raises(RuntimeError):
                 gitman.install(depth=1)
 
         def it_overwrites_files_with_force(config_with_links):
-            os.system("touch gmd_3")
+            Path("gmd_3").touch()
 
             expect(gitman.install(depth=1, force=True)) == True