Merge pull request conda#9093 from forrestwaters/fw_DSNC1492

Add ability to create environment spec from explicit specs in history

conda_env/cli/main_export.py

@@ -68,6 +68,14 @@ def configure_parser(sub_parsers):
         required=False,
         help='Do not include channel names with package names.')
     add_parser_json(p)
+
+    p.add_argument(
+        '--from-history',
+        default=False,
+        action='store_true',
+        required=False,
+        help='Build environment spec from explicit specs in history'
+    )
     p.set_defaults(func='.main_export.execute')
 
 
@@ -91,7 +99,7 @@ def execute(args, parser):
         name = args.name
     prefix = get_prefix(args)
     env = from_environment(name, prefix, no_builds=args.no_builds,
-                           ignore_channels=args.ignore_channels)
+                           ignore_channels=args.ignore_channels, from_history=args.from_history)
 
     if args.override_channels:
         env.remove_channels()

conda_env/env.py

@@ -18,6 +18,7 @@
 from conda.models.prefix_graph import PrefixGraph
 from conda_env.yaml import dump
 from . import compat, exceptions, yaml
+from conda.history import History
 
 try:
     from cytoolz.itertoolz import concatv, groupby
@@ -79,18 +80,24 @@ def load_from_directory(directory):
 
 
 # TODO tests!!!
-def from_environment(name, prefix, no_builds=False, ignore_channels=False):
+def from_environment(name, prefix, no_builds=False, ignore_channels=False, from_history=False):
     """
         Get environment object from prefix
     Args:
         name: The name of environment
         prefix: The path of prefix
         no_builds: Whether has build requirement
         ignore_channels: whether ignore_channels
+        from_history: Whether environment file should be based on explicit specs in history
 
     Returns:     Environment object
     """
     # requested_specs_map = History(prefix).get_requested_specs_map()
+    if from_history:
+        history = History(prefix).get_requested_specs_map()
+        deps = [str(package) for package in history.values()]
+        return Environment(name=name, dependencies=deps, channels=list(context.channels),
+                           prefix=prefix)
     pd = PrefixData(prefix, pip_interop_enabled=True)
 
     precs = tuple(PrefixGraph(pd.iter_records()).graph)

tests/conda_env/test_env.py

@@ -7,6 +7,7 @@
 
 from conda.core.prefix_data import PrefixData
 from conda.base.context import conda_tests_ctxt_mgmt_def_pol
+from conda.models.match_spec import MatchSpec
 from conda.common.io import env_vars
 from conda.common.serialize import yaml_load
 from conda.install import on_win
@@ -15,6 +16,13 @@
 from .utils import make_temp_envs_dir, Commands, run_command
 from tests.test_utils import is_prefix_activated_PATHwise
 
+from conda_env.env import from_environment
+
+try:
+    from unittest.mock import patch
+except ImportError:
+    from mock import patch
+
 
 PYTHON_BINARY = 'python.exe' if on_win else 'bin/python'
 
@@ -383,3 +391,22 @@ def test_create_advanced_pip(self):
                 with open(out_file) as f:
                     d = yaml_load(f)
                 assert {'pip': ['argh==0.26.2']} in d['dependencies']
+
+
+class TestFromEnvironment(unittest.TestCase):
+    def test_from_history(self):
+        # We're not testing that get_requested_specs_map() actually works
+        # assume it gives us back a dict of MatchSpecs
+        with patch('conda.history.History.get_requested_specs_map') as m:
+            m.return_value = {
+                'python': MatchSpec('python=3'),
+                'pytest': MatchSpec('pytest!=3.7.3'),
+                'mock': MatchSpec('mock'),
+                'yaml': MatchSpec('yaml>=0.1')
+            }
+            out = from_environment('mock_env', 'mock_prefix', from_history=True)
+            assert "yaml[version='>=0.1']" in out.to_dict()['dependencies']
+            assert "pytest!=3.7.3" in out.to_dict()['dependencies']
+            assert len(out.to_dict()['dependencies']) == 4
+
+            m.assert_called()