Fix interaction between Task & Task2; add python.ExpressionView & task.RequestsPostData

CHANGELOG.md

@@ -5,11 +5,29 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-<!--
 ## [Unreleased][]
--->
 
-## [1.0.2] - 2019-02-21
+### Added
+
+  - `transformer.python.ExpressionView`: An Expression that wraps a non-Expression
+  (e.g. a Request instance), similarly to how Standalone is a Statement that
+  wraps an Expression. A ExpressionView has a `target` (the wrapped object), a
+  `converter` (function capable of transforming the target into an Expression),
+  and a `name` for inspection purposes.
+
+### Fixed
+
+  - A bug in the conversion between Task and Task2 makes Transformer ignore all
+  changes made by plugins to `Task2.request` in the generated locustfile.
+  Thank you [@xinke2411][] for reporting this! (#33)
+
+### Removed
+
+  - `transformer.task.Task.as_locust_action`: As part of the merge between Task
+  and Task2 (#11). `as_locust_action` generates locustfile code as a string,
+  which is made obsolete by the `transformer.python` syntax tree framework. (#33)
+
+## [1.0.2][] - 2019-02-21
 
 ### Added
 
@@ -38,14 +56,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - `transformer.transform.transform` (#14)
   - `transformer.locust.locustfile` (#14)
 
-## [1.0.1] - 2019-02-12
+## [1.0.1][] - 2019-02-12
 
 ### Fixed
 
   - Fix `transformer` command-line crash due to a missing version identifier. (#17)
   - Publish development releases to PyPI for every merge to the `master` branch. (#17)
 
-## [1.0.0] - 2019-02-11
+## [1.0.0][] - 2019-02-11
 
 ### Added
 
@@ -72,3 +90,5 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 [1.0.2]: https://github.com/zalando-incubator/transformer/compare/v1.0.1...v1.0.2
 [1.0.1]: https://github.com/zalando-incubator/transformer/compare/v1.0.0...v1.0.1
 [1.0.0]: https://github.com/zalando-incubator/transformer/compare/f842c4163e037dc345eaf1992187f58126b7d909...v1.0.0
+
+[@xinke2411]: https://github.com/xinke2411

pyproject.toml

@@ -31,6 +31,7 @@ pendulum = "^2.0"
 chevron = "^0.13"
 docopt = "^0.6.2"
 ecological = "^1.6"
+dataclasses = "^0.6.0"
 
 [tool.poetry.dev-dependencies]
 locustio = "^0.9.0"

transformer/plugins/sanitize_headers.py

@@ -1,5 +1,5 @@
-from transformer.helpers import zip_kv_pairs
 from transformer.plugins import plugin, Contract
+from transformer.request import Header
 from transformer.task import Task2
 
 
@@ -10,17 +10,10 @@ def plugin(task: Task2) -> Task2:
     Converts header names to lowercase to simplify further overriding.
     Removes the cookie header as it is handled by Locust's HttpSession.
     """
-    headers = task.request.headers
-
-    if not isinstance(headers, dict):
-        headers = zip_kv_pairs(headers)
-
-    sanitized_headers = {
-        k.lower(): v
-        for (k, v) in headers.items()
-        if not k.startswith(":") and k.lower() != "cookie"
-    }
-
-    task.request = task.request._replace(headers=sanitized_headers)
+    task.request.headers = [
+        Header(name=h.name.lower(), value=h.value)
+        for h in task.request.headers
+        if not h.name.startswith(":") and h.name.lower() != "cookie"
+    ]
 
     return task

transformer/plugins/test_sanitize_headers.py

@@ -38,7 +38,8 @@ def test_it_removes_headers_beginning_with_a_colon():
 def test_it_downcases_header_names():
     task = task_with_header("Some Name", "some value")
     sanitized_headers = plugin(task).request.headers
-    assert "some name" in sanitized_headers
+    header_names = {h.name for h in sanitized_headers}
+    assert "some name" in header_names
 
 
 def test_it_removes_cookies():

transformer/python.py

@@ -11,8 +11,12 @@
     Tuple,
     cast,
     Iterable,
+    Callable,
+    TypeVar,
 )
 
+from dataclasses import dataclass
+
 IMMUTABLE_EMPTY_DICT = MappingProxyType({})
 
 
@@ -686,3 +690,43 @@ def __repr__(self) -> str:
             self.alias,
             self.comments,
         )
+
+
+_T = TypeVar("_T")
+
+
+@dataclass
+class ExpressionView(Expression):
+    """
+    The promise of an Expression representing an object currently not in
+    Expression format.
+
+    The ExpressionView allows to mix non-Expression objects in the syntax tree,
+    along with a function capable of transforming these objects into actual
+    Expression objects at any time.
+    This is useful when there is a simpler representation than Expression.
+
+    For instance, any Request object can be converted into an equivalent
+    Expression, but Request has a simpler API than Expression for all
+    request-oriented operations like accessing the URL, etc.
+    Embedding a Request in a ExpressionView allows to pretend that the Request is
+    already in Expression format (with all associated benefits) but still use
+    the Request API.
+
+    `target` is a callable returning the non-Expression object. That callable
+    allows to specify as target some mutable field of an object, rather than a
+    fixed reference to an object. See for example task.Task2, which contains a
+    ExpressionView to its own "request" field; if the value of that field is
+    changed, the ExpressionView will refer to the new value instead of keeping a
+    reference to the old value.
+
+    `name` is purely descriptive: it can make inspection of data structures
+    containing ExpressionView objects more comfortable.
+    """
+
+    name: str
+    target: Callable[[], _T]
+    converter: Callable[[_T], Expression]
+
+    def __str__(self) -> str:
+        return str(self.converter(self.target()))

transformer/request.py

@@ -5,10 +5,11 @@
 
 import enum
 from datetime import datetime
-from typing import Iterator, NamedTuple, List
+from typing import Iterator, NamedTuple, List, Optional
 from urllib.parse import urlparse, SplitResult
 
 import pendulum
+from dataclasses import dataclass
 
 from transformer.naming import to_identifier
 
@@ -34,7 +35,8 @@ class Header(NamedTuple):
     value: str
 
 
-class QueryPair(NamedTuple):
+@dataclass
+class QueryPair:
     """
     Query String as recorded in HAR file.
     """
@@ -43,17 +45,27 @@ class QueryPair(NamedTuple):
     value: str
 
 
-class Request(NamedTuple):
+@dataclass
+class Request:
     """
     An HTTP request as recorded in a HAR file.
+
+    Note that *post_data*, if present, will be a dict of the same format as read
+    in the HAR file.
+    Although not consistently followed by HAR generators, his format is
+    documented here: http://www.softwareishard.com/blog/har-12-spec/#postData.
     """
 
     timestamp: datetime
     method: HttpMethod
     url: SplitResult
-    headers: List[Header]
-    post_data: dict
-    query: List[QueryPair]
+    headers: List[Header] = ()
+    post_data: Optional[dict] = None
+    query: List[QueryPair] = ()
+
+    def __post_init__(self):
+        self.headers = list(self.headers)
+        self.query = list(self.query)
 
     @classmethod
     def from_har_entry(cls, entry: dict) -> "Request":
@@ -107,6 +119,6 @@ def __hash__(self) -> int:
                 self.timestamp,
                 self.method,
                 self.url,
-                tuple(self.post_data) if self.post_data else None,
+                tuple(self.post_data.items()) if self.post_data else None,
             )
         )

transformer/scenario.py

@@ -14,7 +14,6 @@
     NamedTuple,
 )
 
-
 import transformer.plugins as plug
 from transformer.naming import to_identifier
 from transformer.plugins.contracts import Plugin