Add an output pager.

Fixes #50.
Requires pallets/click#1572.

sno/diff_output.py

@@ -60,7 +60,7 @@ def diff_output_text(*, output_path, **kwargs):
 
     def _out(dataset, diff):
         with resolve_output_path(output_path) as fp:
-            pecho = {'file': fp, 'color': getattr(fp, 'color', fp.isatty())}
+            pecho = {'file': fp, 'color': True}
             path = dataset.path
             pk_field = dataset.primary_key
             prefix = f"{path}:"

sno/output_util.py

@@ -22,7 +22,7 @@ def dump_json_output(output, output_path, json_style="pretty"):
     """
 
     with resolve_output_path(output_path) as fp:
-        if json_style == 'pretty' and getattr(fp, 'color', fp.isatty()):
+        if json_style == 'pretty':
             # Add syntax highlighting
             from pygments import highlight
             from pygments.lexers import JsonLexer
@@ -62,7 +62,7 @@ def resolve_output_path(output_path, allow_pager=True):
             )
 
             with _push_environment('PAGER', pager_cmd):
-                with click.get_pager_file(color=True) as pager:
+                with click.get_pager_file() as pager:
                     yield pager
         else:
             yield sys.stdout

sno/show.py

@@ -93,7 +93,7 @@ def patch_output_text(*, target, output_path, **kwargs):
     """
     commit = target.head_commit
     with resolve_output_path(output_path) as fp:
-        pecho = {'file': fp, 'color': getattr(fp, 'color', fp.isatty())}
+        pecho = {'file': fp, 'color': True}
         with diff.diff_output_text(output_path=fp, **kwargs) as diff_writer:
             author = commit.author
             author_time_utc = datetime.fromtimestamp(author.time, timezone.utc)