Add preview endpoint and tests

app/v2/template/post_template.py

@@ -0,0 +1,44 @@
+import uuid
+
+from flask import jsonify, request
+from jsonschema.exceptions import ValidationError
+from werkzeug.exceptions import abort
+
+from app import api_user
+from app.dao import templates_dao
+from app.schema_validation import validate
+from app.utils import get_template_instance
+from app.v2.errors import BadRequestError
+from app.v2.template import template_blueprint
+from app.v2.template.template_schemas import post_template_preview_request, create_post_template_preview_response
+
+
+@template_blueprint.route("/<template_id>/preview", methods=['POST'])
+def post_template_preview(template_id):
+    try:
+        _data = request.get_json()
+        _data['id'] = template_id
+
+        data = validate(_data, post_template_preview_request)
+    except ValueError or AttributeError:
+        abort(404)
+
+    template = templates_dao.dao_get_template_by_id_and_service_id(
+        template_id, api_user.service_id)
+
+    template_object = get_template_instance(
+        template.__dict__, values=data.get('personalisation'))
+
+    check_placeholders(template_object)
+
+    resp = create_post_template_preview_response(template=template,
+                                                 body=str(template_object),
+                                                 url_root=request.url_root)
+
+    return jsonify(resp), 200
+
+
+def check_placeholders(template_object):
+    if template_object.missing_data:
+        message = 'Missing personalisation: {}'.format(", ".join(template_object.missing_data))
+        raise BadRequestError(message=message, fields=[{'template': message}])

app/v2/template/template_schemas.py

@@ -66,3 +66,14 @@ post_template_preview_response = {
     },
     "required": ["id", "type", "version", "body"]
 }
+
+
+def create_post_template_preview_response(template, body, url_root):
+    return {
+        "id": template.id,
+        "type": template.template_type,
+        "version": template.version,
+        "content": {'body': body},
+        "subject": template.subject,
+        "uri": "{}v2/template/{}/preview".format(url_root, template.id)
+    }