Factor scenario validation into yarnlib

4 files changed, 156 insertions, 35 deletions

diff --git a/yarn b/yarn
index af25d21..f982e77 100755
--- a/yarn
+++ b/yarn
@@ -1,5 +1,5 @@
 #!/usr/bin/python
-# Copyright 2013  Lars Wirzenius
+# Copyright 2013-2014  Lars Wirzenius
 #
 # 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
@@ -119,9 +119,8 @@ class YarnRunner(cliapp.Application):
                 '%String(step_name)')
 
         scenarios, implementations = self.parse_scenarios(args)
-        self.check_there_are_scenarios(scenarios)
-        self.check_for_duplicate_scenario_names(scenarios)
-        self.check_for_thens(scenarios)
+        sv = yarnlib.ScenarioValidator(scenarios)
+        sv.validate_all()
         scenarios = self.connect_implementations(scenarios, implementations)
         shell_prelude = self.load_shell_libraries()
 
@@ -178,36 +177,6 @@ class YarnRunner(cliapp.Application):
 
         return block_parser.scenarios, block_parser.implementations
 
-    def check_there_are_scenarios(self, scenarios):
-        if not scenarios:
-            raise cliapp.AppException(
-                'There are no scenarios; must have at least one.')
-
-    def check_for_duplicate_scenario_names(self, scenarios):
-        counts = collections.Counter()
-        for s in scenarios:
-            counts[s.name] += 1
-
-        duplicates = [name for name in counts if counts[name] > 1]
-        if duplicates:
-            duplist = ''.join('  %s\n' % name for name in duplicates)
-            raise cliapp.AppException(
-                'There are scenarios with duplicate names:\n%s' % duplist)
-
-    def check_for_thens(self, scenarios):
-        no_thens = []
-        for scenario in scenarios:
-            for step in scenario.steps:
-                if step.what == 'THEN':
-                    break
-            else:
-                no_thens.append(scenario)
-
-        if no_thens:
-            raise cliapp.AppException(
-                'Some scenarios have no THENs:\n%s' %
-                ''.join('  "%s"\n' % s.name for s in no_thens))
-
     def connect_implementations(self, scenarios, implementations):
         new_list = []
         for scenario in scenarios:
diff --git a/yarnlib/__init__.py b/yarnlib/__init__.py
index 88bf46f..f224a0c 100644
--- a/yarnlib/__init__.py
+++ b/yarnlib/__init__.py
@@ -1,4 +1,4 @@
-# Copyright 2013  Lars Wirzenius
+# Copyright 2013-2014  Lars Wirzenius
 #
 # 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
@@ -19,3 +19,5 @@
 from mdparser import MarkdownParser
 from elements import Scenario, ScenarioStep, Implementation
 from block_parser import BlockParser, BlockError
+from scenario_validator import (NoScenariosError, DuplicateScenariosError,
+                                NoThensError, ScenarioValidator)
diff --git a/yarnlib/scenario_validator.py b/yarnlib/scenario_validator.py
new file mode 100644
index 0000000..59c86e7
--- /dev/null
+++ b/yarnlib/scenario_validator.py
@@ -0,0 +1,82 @@
+# 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+ =*=
+
+
+import cliapp
+import collections
+
+
+class NoScenariosError(cliapp.AppException):
+
+    def __init__(self):
+        cliapp.AppException.__init__(
+            self, 'There are no scenarios; must have at least one.')
+
+
+class DuplicateScenariosError(cliapp.AppException):
+
+    def __init__(self, duplicates):
+        duplist = ''.join('  %s\n' % name for name in duplicates)
+        cliapp.AppException.__init__(
+            self, 'There are scenarios with duplicate names:\n%s' % duplist)
+
+
+class NoThensError(cliapp.AppException):
+
+    def __init__(self, thenless):
+        cliapp.AppException.__init__(
+            self,  'Some scenarios have no THENs:\n%s' %
+                   ''.join('  "%s"\n' % s.name for s in thenless))
+
+
+class ScenarioValidator(object):
+
+    def __init__(self, scenarios):
+        self.scenarios = scenarios
+
+    def validate_all(self): # pragma: no cover
+        '''Convenience method to run all checks.'''
+        self.check_there_are_scenarios()
+        self.check_for_duplicate_scenario_names()
+        self.check_for_thens()
+
+    def check_there_are_scenarios(self):
+        '''Check whether any scenarios were found.'''
+        if not self.scenarios:
+            raise NoScenariosError()
+
+    def check_for_duplicate_scenario_names(self):
+        '''Check whether multiple scenarios were found sharing a name.'''
+        counts = collections.Counter()
+        for s in self.scenarios:
+            counts[s.name] += 1
+
+        duplicates = [name for name in counts if counts[name] > 1]
+        if duplicates:
+            raise DuplicateScenariosError(duplicates)
+
+    def check_for_thens(self):
+        no_thens = []
+        for scenario in self.scenarios:
+            for step in scenario.steps:
+                if step.what == 'THEN':
+                    break
+            else:
+                no_thens.append(scenario)
+
+        if no_thens:
+            raise NoThensError(no_thens)
diff --git a/yarnlib/scenario_validator_tests.py b/yarnlib/scenario_validator_tests.py
new file mode 100644
index 0000000..1e482a5
--- /dev/null
+++ b/yarnlib/scenario_validator_tests.py
@@ -0,0 +1,68 @@
+# 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 unittest
+
+import yarnlib
+
+
+class ScenarioValidatorTests(unittest.TestCase):
+
+    def setUp(self):
+        pass
+
+    def test_check_scenarios_fail(self):
+        sv = yarnlib.ScenarioValidator([])
+        with self.assertRaises(yarnlib.NoScenariosError):
+            sv.check_there_are_scenarios()
+
+    def test_check_scenarios_pass(self):
+        sv = yarnlib.ScenarioValidator([
+            yarnlib.Scenario('foo')
+        ])
+        sv.check_there_are_scenarios()
+
+    def test_check_duplicate_names_fail(self):
+        sv = yarnlib.ScenarioValidator([
+            yarnlib.Scenario('foo'),
+            yarnlib.Scenario('foo'),
+        ])
+        with self.assertRaises(yarnlib.DuplicateScenariosError):
+            sv.check_for_duplicate_scenario_names()
+
+    def test_check_duplicate_names_pass(self):
+        sv = yarnlib.ScenarioValidator([
+            yarnlib.Scenario('foo'),
+            yarnlib.Scenario('bar'),
+        ])
+        sv.check_for_duplicate_scenario_names()
+
+    def test_check_for_thens_fail(self):
+        sv = yarnlib.ScenarioValidator([
+            yarnlib.Scenario('foo')
+        ])
+        with self.assertRaises(yarnlib.NoThensError):
+            sv.check_for_thens()
+
+    def test_check_for_thens_pass(self):
+        scenario = yarnlib.Scenario('foo')
+        scenario.steps = [
+            yarnlib.ScenarioStep('THEN', 'badger stoat')
+        ]
+        sv = yarnlib.ScenarioValidator([scenario])
+        sv.check_for_thens()