adding tests for was_changed.

tests/rules/test_was_changed.py

@@ -0,0 +1,45 @@
+import os
+import time
+from uranium.rules import rule, WasChanged
+
+
+def test_unchanged(tmpdir, build):
+
+    g = []
+
+    tmpdir.join("foo.txt").write("foo")
+
+    @build.task
+    @rule(WasChanged("./foo.txt"))
+    def main(build):
+        g.append("ran")
+
+    build.run_task("main")
+    assert "ran" in g
+    build.run_task("main")
+    assert len(g) == 1
+
+
+def test_changed(tmpdir, build):
+
+    g = []
+
+    f_path = os.path.join(tmpdir.strpath, "foo.txt")
+
+    with open(f_path, "w+") as fh:
+        fh.write("foo")
+
+    @build.task
+    @rule(WasChanged("./foo.txt"))
+    def main(build):
+        g.append("ran")
+
+    build.run_task("main")
+    assert "ran" in g
+    # for some reason we need a sleep
+    # here. I think it's not considering
+    # milliseconds.
+    time.sleep(1)
+    os.utime(f_path)
+    build.run_task("main")
+    assert len(g) == 2

uranium/rules/__init__.py

@@ -1,25 +1,9 @@
 import functools
-from abc import ABCMeta, abstractmethod
 from ..experimental import experimental
+from .base import RuleBase
+from .was_changed import WasChanged
 
-
-class RuleBase(object):
-    """
-    an example of a rule.
-
-    * func gets set during the initialization process.
-    """
-    func = None
-
-    __metaclass__ = ABCMeta
-
-    @abstractmethod
-    def before(self, build):
-        pass
-
-    @abstractmethod
-    def after(self, build):
-        pass
+__all__ = ["RuleBase", "WasChanged", "rule"]
 
 
 @experimental

uranium/rules/base.py

@@ -0,0 +1,20 @@
+from abc import ABCMeta, abstractmethod
+
+
+class RuleBase(object):
+    """
+    an example of a rule.
+
+    * func gets set during the initialization process.
+    """
+    func = None
+
+    __metaclass__ = ABCMeta
+
+    @abstractmethod
+    def before(self, build):
+        pass
+
+    @abstractmethod
+    def after(self, build):
+        pass

uranium/rules/was_changed.py

@@ -1,6 +1,6 @@
 import os
 import time
-from . import RuleBase
+from .base import RuleBase
 KEY = "_uranium.rules.was_changed"
 
 
@@ -9,15 +9,18 @@ class WasChanged(RuleBase):
     def __init__(self, path):
         self._path = path
 
+    def path(self, build):
+        return os.path.join(build.root, self._path)
+
     def before(self, build):
         previous_timestamp = build.history.get(self.key)
         if not previous_timestamp:
             return False
-        current_timestamp = self._get_timestamp(self.path)
-        return current_timestamp > previous_timestamp
+        current_timestamp = self._get_timestamp(self.path(build))
+        return current_timestamp <= previous_timestamp
 
     def after(self, build):
-        current_timestamp = self._get_timestamp(self.path)
+        current_timestamp = self._get_timestamp(self.path(build))
         build.history[self.key] = current_timestamp
 
     @property