Create concat function and provide validation

Create concat function to validat the concat function specified in the
template.

Change-Id: I25385f6c7555755b5a0cc6913b9fcedaf2559492
Partially-Implements: tosca-intrinsic-functions

toscaparser/functions.py

@@ -26,6 +26,7 @@ from toscaparser.utils.gettextutils import _
 GET_PROPERTY = 'get_property'
 GET_ATTRIBUTE = 'get_attribute'
 GET_INPUT = 'get_input'
+CONCAT = 'concat'
 
 SELF = 'SELF'
 HOST = 'HOST'
@@ -522,10 +523,39 @@ class GetProperty(Function):
         return None
 
 
+class Concat(Function):
+    """Validate the function and provide an instance of the function
+
+    Concatenation of values are supposed to be produced at runtime and
+    therefore its the responsibility of the TOSCA engine to implement the
+    evaluation of Concat functions.
+
+    Arguments:
+
+    * List of strings that needs to be concatenated
+
+    Example:
+
+      [ 'http://',
+        get_attribute: [ server, public_address ],
+        ':' ,
+        get_attribute: [ server, port ] ]
+    """
+
+    def validate(self):
+        if len(self.args) < 1:
+            ExceptionCollector.appendException(
+                ValueError(_('Invalid arguments for function "{0}". Expected '
+                             'at least one arguments.').format(CONCAT)))
+
+    def result(self):
+        return self
+
 function_mappings = {
     GET_PROPERTY: GetProperty,
     GET_INPUT: GetInput,
-    GET_ATTRIBUTE: GetAttribute
+    GET_ATTRIBUTE: GetAttribute,
+    CONCAT: Concat
 }
 
 

toscaparser/tests/data/functions/test_concat.yaml

@@ -0,0 +1,30 @@
+tosca_definitions_version: tosca_simple_yaml_1_0
+
+description: Template for deploying a single server with concat function.
+
+topology_template:
+  node_templates:
+    server:
+      type: tosca.nodes.Compute
+      capabilities:
+        # Host container properties
+        host:
+         properties:
+           num_cpus: 2
+           disk_size: 10 GB
+           mem_size: 512 MB
+        # Guest Operating System properties
+        os:
+          properties:
+            # host Operating System image properties
+            architecture: x86_64
+            type: Linux
+            distribution: RHEL
+            version: 6.5
+  outputs:
+    url:
+      description: Concatenate the URL for a server from template values.
+      value: { concat: [ 'http://',
+                         get_attribute: [ server, public_address ],
+                         ':' ,
+                         get_attribute: [ server, port ] ] }

toscaparser/tests/data/functions/test_concat_invalid.yaml

@@ -0,0 +1,9 @@
+tosca_definitions_version: tosca_simple_yaml_1_0
+
+description: Template for deploying a single server with invalid concat function.
+
+topology_template:
+  outputs:
+    invalid_concat_syntax:
+      description: test concat with invalid syntax.
+      value: { concat: []}

toscaparser/tests/test_functions.py

@@ -299,3 +299,26 @@ class GetAttributeTest(TestCase):
         self.assertTrue(isinstance(target_test, functions.GetAttribute))
         source_port = operation.inputs['source_port']
         self.assertTrue(isinstance(source_port, functions.GetAttribute))
+
+
+class ConcatTest(TestCase):
+
+    def _load_template(self, filename):
+        return ToscaTemplate(os.path.join(
+            os.path.dirname(os.path.abspath(__file__)),
+            filename))
+
+    def test_validate_concat(self):
+        tosca = self._load_template("data/functions/test_concat.yaml")
+        server_url_output = [
+            output for output in tosca.outputs if output.name == 'url'][0]
+        func = functions.get_function(self, tosca.outputs,
+                                      server_url_output.value)
+        self.assertIsInstance(func, functions.Concat)
+
+        self.assertRaises(exception.ValidationError, self._load_template,
+                          'data/functions/test_concat_invalid.yaml')
+        exception.ExceptionCollector.assertExceptionMessage(
+            ValueError,
+            _('Invalid arguments for function "concat". Expected at least '
+              'one arguments.'))