node.pyx: Support loading 0/1 as boolean values

src/buildstream/node.pyx

@@ -306,8 +306,8 @@ cdef class ScalarNode(Node):
     cpdef bint as_bool(self) except *:
         """Get the value of the node as a boolean.
 
-        .. note:: BuildStream treats the values 'True' and 'true' as True,
-                  and the values 'False' and 'false' as False.  Any other
+        .. note:: BuildStream treats the values 'True', 'true' and '1' as True,
+                  and the values 'False', 'false' and '0' as False.  Any other
                   string values (such as the valid YAML 'TRUE' or 'FALSE'
                   will be considered as an error)
 
@@ -322,15 +322,15 @@ cdef class ScalarNode(Node):
             return self.value
 
         # Don't coerce strings to booleans, this makes "False" strings evaluate to True
-        if self.value in ('True', 'true'):
+        if self.value in ('True', 'true', '1'):
             return True
-        elif self.value in ('False', 'false'):
+        elif self.value in ('False', 'false', '0'):
             return False
         else:
             provenance = self.get_provenance()
             path = provenance._toplevel._find(self)[-1]
-            raise LoadError("{}: Value of '{}' is not of the expected type '{}'"
-                            .format(provenance, path, bool.__name__, self.value),
+            raise LoadError("{}: Value of '{}' is not of the expected type 'boolean'"
+                            .format(provenance, path),
                             LoadErrorReason.INVALID_DATA)
 
     cpdef object as_enum(self, object constraint):

tests/format/option-exports/element.bst

@@ -1 +1,5 @@
-kind: manual
+kind: config
+
+config:
+  animal: "%{exported-enum}"
+  sleepy: "%{exported-bool}"

tests/format/option-exports/plugins/config.py

@@ -0,0 +1,26 @@
+from buildstream import Element, FastEnum
+
+
+class AnimalEnum(FastEnum):
+    PONY = "pony"
+    HORSY = "horsy"
+    ZEBRY = "zebry"
+
+
+class Config(Element):
+    BST_MIN_VERSION = "2.0"
+
+    def configure(self, node):
+        self.animal = node.get_enum("animal", AnimalEnum)
+        self.sleepy = node.get_bool("sleepy")
+
+    def preflight(self):
+        pass
+
+    def get_unique_key(self):
+        return {}
+
+
+# Plugin entry point
+def setup():
+    return Config

tests/format/option-exports/project.conf

@@ -1,6 +1,12 @@
 name: test
 min-version: 2.0
 
+plugins:
+  - origin: local
+    path: plugins
+    elements:
+    - config
+
 options:
 
   bool_export:

tests/integration/pullbuildtrees.py

@@ -179,7 +179,7 @@ def test_pullbuildtrees(cli2, tmpdir, datafiles):
 
 # Ensure that only valid pull-buildtrees boolean options make it through the loading
 # process.
-@pytest.mark.parametrize("value,success", [(True, True), (False, True), ("pony", False), ("1", False)])
+@pytest.mark.parametrize("value,success", [(True, True), (False, True), ("pony", False), ("2", False), ("1", True)])
 @pytest.mark.datafiles(DATA_DIR)
 def test_invalid_cache_pullbuildtrees(cli, datafiles, value, success):
     project = str(datafiles)