Factor out shell library loading into yarnlib

4 files changed, 109 insertions, 8 deletions

diff --git a/yarn b/yarn
index f982e77..cc794f7 100755
--- a/yarn
+++ b/yarn
@@ -222,14 +222,9 @@ class YarnRunner(cliapp.Application):
             self.info('No shell libraries defined')
             return ''
 
-        libs = []
-        for filename in self.settings['shell-library']:
-            self.info('Loading shell library %s' % filename)
-            with open(filename) as f:
-                text = f.read()
-            libs.append('# Loaded from %s\n\n%s\n\n' % (filename, text))
-
-        return ''.join(libs)
+        return yarnlib.load_shell_libraries(
+            self.settings['shell-library'],
+            pre_read_cb=lambda fn: self.info('Loading shell library %s' % fn))
 
     def select_scenarios(self, scenarios):
 
diff --git a/yarnlib/__init__.py b/yarnlib/__init__.py
index f224a0c..b5b207d 100644
--- a/yarnlib/__init__.py
+++ b/yarnlib/__init__.py
@@ -21,3 +21,5 @@ from elements import Scenario, ScenarioStep, Implementation
 from block_parser import BlockParser, BlockError
 from scenario_validator import (NoScenariosError, DuplicateScenariosError,
                                 NoThensError, ScenarioValidator)
+
+from shell_libraries import load_shell_libraries
diff --git a/yarnlib/shell_libraries.py b/yarnlib/shell_libraries.py
new file mode 100644
index 0000000..3607adc
--- /dev/null
+++ b/yarnlib/shell_libraries.py
@@ -0,0 +1,45 @@
+# Copyright 2014  Lars Wirzenius and Codethink Limited
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# =*= License: GPL-3+ =*=
+
+
+def load_shell_libraries(paths, pre_read_cb=lambda filename: None, open=open):
+    '''Helper for loading shell libraries from files.
+
+    `paths`: Iterable of file paths to shell libraries.
+    `pre_read_cb`: Optional callback for providing progress reporting
+                   and logging.
+                   It is given only one parameter, of the path to the
+                   shell library that is about to be loaded.
+    `open`: Optional function for opening file paths. This is useful to
+            override how files are opened for unit tests or virtual
+            file systems.
+
+    This function is provided so that when shell libraries are loaded
+    by applications that use yarnlib, they can all load them with the
+    same format, including the comments about where the snippet came from,
+    and any future additions.
+
+    '''
+
+    libs = []
+    for filename in paths:
+        pre_read_cb(filename)
+        with open(filename) as f:
+            text = f.read()
+        libs.append('# Loaded from %s\n\n%s\n\n' % (filename, text))
+
+    return ''.join(libs)
diff --git a/yarnlib/shell_libraries_tests.py b/yarnlib/shell_libraries_tests.py
new file mode 100644
index 0000000..69e015a
--- /dev/null
+++ b/yarnlib/shell_libraries_tests.py
@@ -0,0 +1,59 @@
+# Copyright 2014  Codethink Limited
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# =*= License: GPL-3+ =*=
+
+
+import contextlib
+import StringIO
+import unittest
+
+import yarnlib
+
+
+class ShellLibrariesTests(unittest.TestCase):
+
+    libfiles = {
+        'die.shlib': '''
+        die() {
+            echo "$@" >&2
+            return 1
+        }
+        ''',
+        'chdir.shlib':'''
+        chdir() {
+            (
+                cd "$1"
+                shift
+                exec "$@"
+            )
+        }
+        ''',
+    }
+
+    def fakeopen(self, path, *args, **kwargs):
+        return contextlib.closing(StringIO.StringIO(self.libfiles[path]))
+
+    def test_file_names_listed(self):
+        prelude = yarnlib.load_shell_libraries(self.libfiles.keys(),
+                                               open=self.fakeopen)
+        for filename in self.libfiles.iterkeys():
+            self.assertIn(filename, prelude)
+
+    def test_all_contents_included(self):
+        prelude = yarnlib.load_shell_libraries(self.libfiles.keys(),
+                                               open=self.fakeopen)
+        for contents in self.libfiles.itervalues():
+            self.assertIn(contents, prelude)