env: make spack config edit and spack config get environment-aware

- with no arguments, these commands will now edit or dump the
  environment's `spack.yaml` file.

- users may not know where named environments live

- this makes it convenient for users to get to the spack.yaml
  configuration file for their named environment.

lib/spack/spack/cmd/config.py

@@ -3,7 +3,13 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
+from __future__ import print_function
+import os
+
+import llnl.util.tty as tty
+
 import spack.config
+import spack.environment as ev
 
 from spack.util.editor import editor
 
@@ -27,6 +33,7 @@ def setup_parser(subparser):
     get_parser.add_argument('section',
                             help="configuration section to print. "
                                  "options: %(choices)s",
+                            nargs='?',
                             metavar='SECTION',
                             choices=spack.config.section_schemas)
 
@@ -43,29 +50,81 @@ def setup_parser(subparser):
                              help="configuration section to edit. "
                                   "options: %(choices)s",
                              metavar='SECTION',
+                             nargs='?',
                              choices=spack.config.section_schemas)
+    edit_parser.add_argument(
+        '--print-file', action='store_true',
+        help="print the file name that would be edited")
+
+
+def _get_scope_and_section(args):
+    """Extract config scope and section from arguments."""
+    scope = args.scope
+    section = args.section
+
+    # w/no args and an active environment, point to env manifest
+    if not args.section:
+        env = ev.get_env(args, 'config edit', required=False)
+        if env:
+            scope = env.env_file_config_scope_name()
+
+    # set scope defaults
+    elif not args.scope:
+        if section == 'compilers':
+            scope = spack.config.default_modify_scope()
+        else:
+            scope = 'user'
+
+    return scope, section
 
 
 def config_get(args):
-    spack.config.config.print_section(args.section)
+    """Dump merged YAML configuration for a specific section.
+
+    With no arguments and an active environment, print the contents of
+    the environment's manifest file (spack.yaml).
+
+    """
+    scope, section = _get_scope_and_section(args)
+
+    if scope and scope.startswith('env:'):
+        config_file = spack.config.config.get_config_filename(scope, section)
+        if os.path.exists(config_file):
+            with open(config_file) as f:
+                print(f.read())
+        else:
+            tty.die('environment has no %s file' % ev.manifest_name)
+
+    elif section is not None:
+        spack.config.config.print_section(section)
+
+    else:
+        tty.die('`spack config get` requires a section argument '
+                'or an active environment.')
 
 
 def config_blame(args):
+    """Print out line-by-line blame of merged YAML."""
     spack.config.config.print_section(args.section, blame=True)
 
 
 def config_edit(args):
-    if not args.scope:
+    """Edit the configuration file for a specific scope and config section.
-        if args.section == 'compilers':
-            args.scope = spack.config.default_modify_scope()
-        else:
-            args.scope = 'user'
-    if not args.section:
-        args.section = None
 
-    config = spack.config.config
+    With no arguments and an active environment, edit the spack.yaml for
-    config_file = config.get_config_filename(args.scope, args.section)
+    the active environment.
-    editor(config_file)
+
+    """
+    scope, section = _get_scope_and_section(args)
+    if not scope and not section:
+        tty.die('`spack config edit` requires a section argument '
+                'or an active environment.')
+
+    config_file = spack.config.config.get_config_filename(scope, section)
+    if args.print_file:
+        print(config_file)
+    else:
+        editor(config_file)
 
 
 def config(parser, args):

lib/spack/spack/environment.py

@@ -483,9 +483,13 @@ def included_config_scopes(self):
 
         return scopes
 
+    def env_file_config_scope_name(self):
+        """Name of the config scope of this environment's manifest file."""
+        return 'env:%s' % self.name
+
     def env_file_config_scope(self):
         """Get the configuration scope for the environment's manifest file."""
-        config_name = 'env:%s' % self.name
+        config_name = self.env_file_config_scope_name()
         return spack.config.SingleFileScope(config_name,
                                             self.manifest_path,
                                             spack.schema.env.schema,

lib/spack/spack/test/cmd/config.py

@@ -0,0 +1,93 @@
+# Copyright 2013-2018 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+import os
+
+from llnl.util.filesystem import mkdirp
+
+import spack.config
+import spack.environment as ev
+from spack.main import SpackCommand
+
+config = SpackCommand('config')
+
+
+def test_get_config_scope(mock_config):
+    assert config('get', 'compilers').strip() == 'compilers: {}'
+
+
+def test_get_config_scope_merged(mock_config):
+    low_path = mock_config.scopes['low'].path
+    high_path = mock_config.scopes['high'].path
+
+    mkdirp(low_path)
+    mkdirp(high_path)
+
+    with open(os.path.join(low_path, 'repos.yaml'), 'w') as f:
+        f.write('''\
+repos:
+- repo3
+''')
+
+    with open(os.path.join(high_path, 'repos.yaml'), 'w') as f:
+        f.write('''\
+repos:
+- repo1
+- repo2
+''')
+
+    assert config('get', 'repos').strip() == '''repos:
+- repo1
+- repo2
+- repo3'''
+
+
+def test_config_edit():
+    """Ensure `spack config edit` edits the right paths."""
+    dms = spack.config.default_modify_scope()
+    dms_path = spack.config.config.scopes[dms].path
+    user_path = spack.config.config.scopes['user'].path
+
+    comp_path = os.path.join(dms_path, 'compilers.yaml')
+    repos_path = os.path.join(user_path, 'repos.yaml')
+
+    assert config('edit', '--print-file', 'compilers').strip() == comp_path
+    assert config('edit', '--print-file', 'repos').strip() == repos_path
+
+
+def test_config_get_gets_spack_yaml(mutable_mock_env_path):
+    env = ev.create('test')
+
+    config('get', fail_on_error=False)
+    assert config.returncode == 1
+
+    with env:
+        config('get', fail_on_error=False)
+        assert config.returncode == 1
+
+        env.write()
+
+        assert 'mpileaks' not in config('get')
+
+        env.add('mpileaks')
+        env.write()
+
+        assert 'mpileaks' in config('get')
+
+
+def test_config_edit_edits_spack_yaml(mutable_mock_env_path):
+    env = ev.create('test')
+    with env:
+        assert config('edit', '--print-file').strip() == env.manifest_path
+
+
+def test_config_edit_fails_correctly_with_no_env(mutable_mock_env_path):
+    output = config('edit', '--print-file', fail_on_error=False)
+    assert "requires a section argument or an active environment" in output
+
+
+def test_config_get_fails_correctly_with_no_env(mutable_mock_env_path):
+    output = config('get', fail_on_error=False)
+    assert "requires a section argument or an active environment" in output

lib/spack/spack/test/config.py

@@ -49,20 +49,6 @@
         'build_stage:': ['patha', 'pathb']}}
 
 
-@pytest.fixture()
-def mock_config(tmpdir):
-    """Mocks the configuration scope."""
-    real_configuration = spack.config.config
-
-    spack.config.config = spack.config.Configuration(
-        *[spack.config.ConfigScope(name, str(tmpdir.join(name)))
-          for name in ['low', 'high']])
-
-    yield spack.config.config
-
-    spack.config.config = real_configuration
-
-
 @pytest.fixture()
 def write_config_file(tmpdir):
     """Returns a function that writes a config file."""

lib/spack/spack/test/conftest.py

@@ -309,6 +309,20 @@ def mutable_config(tmpdir_factory, configuration_dir, config):
     spack.package_prefs.PackagePrefs.clear_caches()
 
 
+@pytest.fixture()
+def mock_config(tmpdir):
+    """Mocks two configuration scopes: 'low' and 'high'."""
+    real_configuration = spack.config.config
+
+    spack.config.config = spack.config.Configuration(
+        *[spack.config.ConfigScope(name, str(tmpdir.join(name)))
+          for name in ['low', 'high']])
+
+    yield spack.config.config
+
+    spack.config.config = real_configuration
+
+
 def _populate(mock_db):
     r"""Populate a mock database with packages.