bump: version 0.26.0 → 0.27.0

sometimes (e.g. for "import/export warning") we need some common
template and/or config

CHANGELOG.md

@@ -5,6 +5,17 @@ All notable changes to WuttJamaican will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## v0.27.0 (2025-12-20)
+
+### Feat
+
+- add simple Diff class, to render common table
+
+### Fix
+
+- add `fallback_key` support for email settings
+- include thousands separator for `app.render_quantity()`
+
 ## v0.26.0 (2025-12-17)
 
 ### Feat

docs/api/wuttjamaican.diffs.rst

@@ -0,0 +1,6 @@
+
+``wuttjamaican.diffs``
+======================
+
+.. automodule:: wuttjamaican.diffs
+   :members:

docs/glossary.rst

@@ -203,10 +203,11 @@ Glossary
      setting` definitions.
 
    email setting
-     This refers to the settings for a particular :term:`email type`,
-     i.e. its sender and recipients, subject etc.  So each email type
-     has a "collection" of settings, and that collection is referred
-     to simply as an "email setting" in the singular.
+     This refers to the :term:`config settings <config setting>` for a
+     particular :term:`email type`, i.e. its sender and recipients,
+     subject etc.  So each email type has a "collection" of settings,
+     and that collection is referred to simply as an "email setting"
+     in the singular.
 
    email template
       Usually this refers to the HTML or TXT template file, used to

docs/index.rst

@@ -90,6 +90,7 @@ Contents
    api/wuttjamaican.db.model.upgrades
    api/wuttjamaican.db.sess
    api/wuttjamaican.db.util
+   api/wuttjamaican.diffs
    api/wuttjamaican.email
    api/wuttjamaican.enum
    api/wuttjamaican.exc

docs/narr/email/sending.rst

@@ -10,8 +10,8 @@ Basics
 
 To send an email you (usually) need 3 things:
 
-* key - unique key identifying the type of email
-* template - template file to render message body
+* key - unique key identifying the :term:`email type`
+* template - :term:`email template` file to render message body
 * context - context dict for template file rendering
 
 And actually the template just needs to exist somewhere it can be

pyproject.toml

@@ -6,7 +6,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "WuttJamaican"
-version = "0.26.0"
+version = "0.27.0"
 description = "Base package for Wutta Framework"
 readme = "README.md"
 authors = [{name = "Lance Edgar", email = "lance@wuttaproject.org"}]
@@ -37,6 +37,7 @@ dependencies = [
         "python-configuration",
         "typer",
         "uuid7",
+        "WebHelpers2",
 ]
 
 

src/wuttjamaican/app.py

@@ -962,8 +962,8 @@ class AppHandler:  # pylint: disable=too-many-public-methods
             value = int(value)
             if empty_zero and value == 0:
                 return ""
-            return str(value)
-        return str(value).rstrip("0")
+            return f"{value:,}"
+        return f"{value:,}".rstrip("0")
 
     def render_time_ago(self, value):
         """

src/wuttjamaican/diffs.py

@@ -0,0 +1,186 @@
+# -*- coding: utf-8; -*-
+################################################################################
+#
+#  WuttJamaican -- Base package for Wutta Framework
+#  Copyright © 2023-2025 Lance Edgar
+#
+#  This file is part of Wutta Framework.
+#
+#  Wutta Framework is free software: you can redistribute it and/or modify it
+#  under the terms of the GNU General Public License as published by the Free
+#  Software Foundation, either version 3 of the License, or (at your option) any
+#  later version.
+#
+#  Wutta Framework is distributed in the hope that it will be useful, but
+#  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+#  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+#  more details.
+#
+#  You should have received a copy of the GNU General Public License along with
+#  Wutta Framework.  If not, see <http://www.gnu.org/licenses/>.
+#
+################################################################################
+"""
+Tools for displaying simple data diffs
+"""
+
+from mako.template import Template
+from webhelpers2.html import HTML
+
+
+class Diff:  # pylint: disable=too-many-instance-attributes
+    """
+    Represent / display a basic "diff" between two data records.
+
+    You must provide both the "old" and "new" data records, when
+    constructing an instance of this class.  Then call
+    :meth:`render_html()` to display the diff table.
+
+    :param config: The app :term:`config object`.
+
+    :param old_data: Dict of "old" data record.
+
+    :param new_data: Dict of "new" data record.
+
+    :param fields: Optional list of field names.  If not specified,
+       will be derived from the data records.
+
+    :param nature: What sort of diff is being represented; must be one
+       of: ``("create", "update", "delete")``
+
+    :param old_color: Background color to display for "old/deleted"
+       field data, when applicable.
+
+    :param new_color: Background color to display for "new/created"
+       field data, when applicable.
+
+    :param cell_padding: Optional override for cell padding style.
+    """
+
+    cell_padding = "0.25rem"
+
+    def __init__(  # pylint: disable=too-many-arguments,too-many-positional-arguments
+        self,
+        config,
+        old_data: dict,
+        new_data: dict,
+        fields: list = None,
+        nature="update",
+        old_color="#ffebe9",
+        new_color="#dafbe1",
+        cell_padding=None,
+    ):
+        self.config = config
+        self.app = self.config.get_app()
+        self.old_data = old_data
+        self.new_data = new_data
+        self.columns = ["field name", "old value", "new value"]
+        self.fields = fields or self.make_fields()
+        self.nature = nature
+        self.old_color = old_color
+        self.new_color = new_color
+        if cell_padding:
+            self.cell_padding = cell_padding
+
+    def make_fields(self):  # pylint: disable=missing-function-docstring
+        return sorted(set(self.old_data) | set(self.new_data), key=lambda x: x.lower())
+
+    def render_html(self, template=None, **kwargs):
+        """
+        Render the diff as HTML table.
+
+        :param template: Name of template to render, if you need to
+           override the default.
+
+        :param \\**kwargs: Remaining kwargs are passed as context to
+           the template renderer.
+
+        :returns: HTML literal string
+        """
+        context = kwargs
+        context["diff"] = self
+
+        if not isinstance(template, Template):
+            path = self.app.resource_path(
+                template or "wuttjamaican:templates/diff.mako"
+            )
+            template = Template(filename=path)
+
+        return HTML.literal(template.render(**context))
+
+    def render_field_row(self, field):  # pylint: disable=missing-function-docstring
+        is_diff = self.values_differ(field)
+
+        kw = {}
+        if self.cell_padding:
+            kw["style"] = f"padding: {self.cell_padding}"
+        td_field = HTML.tag("td", class_="field", c=field, **kw)
+
+        td_old_value = HTML.tag(
+            "td",
+            c=self.render_old_value(field),
+            **self.get_old_value_attrs(is_diff),
+        )
+
+        td_new_value = HTML.tag(
+            "td",
+            c=self.render_new_value(field),
+            **self.get_new_value_attrs(is_diff),
+        )
+
+        return HTML.tag("tr", c=[td_field, td_old_value, td_new_value])
+
+    def render_cell_value(self, value):  # pylint: disable=missing-function-docstring
+        return HTML.tag("span", c=[value], style="font-family: monospace;")
+
+    def render_old_value(self, field):  # pylint: disable=missing-function-docstring
+        value = "" if self.nature == "create" else repr(self.old_value(field))
+        return self.render_cell_value(value)
+
+    def render_new_value(self, field):  # pylint: disable=missing-function-docstring
+        value = "" if self.nature == "delete" else repr(self.new_value(field))
+        return self.render_cell_value(value)
+
+    def get_cell_attrs(  # pylint: disable=missing-function-docstring
+        self, style=None, **attrs
+    ):
+        style = dict(style or {})
+
+        if self.cell_padding and "padding" not in style:
+            style["padding"] = self.cell_padding
+
+        if style:
+            attrs["style"] = "; ".join([f"{k}: {v}" for k, v in style.items()])
+
+        return attrs
+
+    def get_old_value_attrs(  # pylint: disable=missing-function-docstring
+        self, is_diff
+    ):
+        style = {}
+        if self.nature == "update" and is_diff:
+            style["background-color"] = self.old_color
+        elif self.nature == "delete":
+            style["background-color"] = self.old_color
+
+        return self.get_cell_attrs(style)
+
+    def get_new_value_attrs(  # pylint: disable=missing-function-docstring
+        self, is_diff
+    ):
+        style = {}
+        if self.nature == "create":
+            style["background-color"] = self.new_color
+        elif self.nature == "update" and is_diff:
+            style["background-color"] = self.new_color
+
+        return self.get_cell_attrs(style)
+
+    def old_value(self, field):  # pylint: disable=missing-function-docstring
+        return self.old_data.get(field)
+
+    def new_value(self, field):  # pylint: disable=missing-function-docstring
+        return self.new_data.get(field)
+
+    def values_differ(self, field):  # pylint: disable=missing-function-docstring
+        return self.new_value(field) != self.old_value(field)

src/wuttjamaican/email.py

@@ -23,8 +23,10 @@
 """
 Email Handler
 """
+# pylint: disable=too-many-lines
 
 import logging
+import re
 import smtplib
 from email.mime.multipart import MIMEMultipart
 from email.mime.text import MIMEText
@@ -60,6 +62,7 @@ class EmailSetting:  # pylint: disable=too-few-public-methods
 
            default_subject = "Something happened!"
 
+           # nb. this is not used for sending; only preview
            def sample_data(self):
                return {
                    'foo': 1234,
@@ -84,23 +87,80 @@ class EmailSetting:  # pylint: disable=too-few-public-methods
     * allows for hard-coded sample context which can be used to render
       templates for preview
 
+    .. attribute:: key
+
+       Unique identifier for this :term:`email type`.
+
+       This is the :term:`email key` used for config/template lookup,
+       e.g. when sending an email.
+
+       This is automatically set based on the *class name* so there is
+       no need (or point) to set it.  But the attribute is here for
+       read access, for convenience / code readability::
+
+          class poser_alert_foo(EmailSetting):
+             default_subject = "Something happened!"
+
+          handler = app.get_email_handler()
+          setting = handler.get_email_setting("poser_alert_foo")
+          assert setting.key == "poser_alert_foo"
+
+       See also :attr:`fallback_key`.
+
     .. attribute:: default_subject
 
-       Default :attr:`Message.subject` for the email, if none is
-       configured.
+       Default subject for sending emails of this type.
+
+       Usually, if config does not override, this will become
+       :attr:`Message.subject`.
 
        This is technically a Mako template string, so it will be
        rendered with the email context.  But in most cases that
        feature can be ignored, and this will be a simple string.
+
+       Calling code should not access this directly, but instead use
+       :meth:`get_default_subject()` .
     """
 
     default_subject = None
 
+    fallback_key = None
+    """
+    Optional fallback key to use for config/template lookup, if
+    nothing is found for :attr:`key`.
+    """
+
     def __init__(self, config):
         self.config = config
         self.app = config.get_app()
         self.key = self.__class__.__name__
 
+    def get_description(self):
+        """
+        This must return the full description for the :term:`email
+        type`.  It is not used for the sending of email; only for
+        settings administration.
+
+        Default logic will use the class docstring.
+
+        :returns: String description for the email type
+        """
+        return self.__class__.__doc__.strip()
+
+    def get_default_subject(self):
+        """
+        This must return the default subject, for sending emails of
+        this type.
+
+        If config does not override, this will become
+        :attr:`Message.subject`.
+
+        Default logic here returns :attr:`default_subject` as-is.
+
+        :returns: Default subject as string
+        """
+        return self.default_subject
+
     def sample_data(self):
         """
         Should return a dict with sample context needed to render the
@@ -325,13 +385,18 @@ class EmailHandler(GenericHandler):  # pylint: disable=too-many-public-methods
         """
         if "email_settings" not in self.classes:
             self.classes["email_settings"] = {}
+
+            # nb. we only want lower_case_names - all UpperCaseNames
+            # are assumed to be base classes
+            pattern = re.compile(r"^[a-z]")
+
             for module in self.get_email_modules():
                 for name in dir(module):
                     obj = getattr(module, name)
                     if (
                         isinstance(obj, type)
-                        and obj is not EmailSetting
                         and issubclass(obj, EmailSetting)
+                        and pattern.match(obj.__name__)
                     ):
                         self.classes["email_settings"][obj.__name__] = obj
 
@@ -368,7 +433,9 @@ class EmailHandler(GenericHandler):  # pylint: disable=too-many-public-methods
         """
         return Message(**kwargs)
 
-    def make_auto_message(self, key, context=None, default_subject=None, **kwargs):
+    def make_auto_message(
+        self, key, context=None, default_subject=None, fallback_key=None, **kwargs
+    ):
         """
         Make a new email message using config to determine its
         properties, and auto-generating body from a template.
@@ -379,7 +446,8 @@ class EmailHandler(GenericHandler):  # pylint: disable=too-many-public-methods
 
         :param key: Unique key for this particular "type" of message.
            This key is used as a prefix for all config settings and
-           template names pertinent to the message.
+           template names pertinent to the message.  See also the
+           ``fallback_key`` param, below.
 
         :param context: Context dict used to render template(s) for
            the message.
@@ -387,6 +455,10 @@ class EmailHandler(GenericHandler):  # pylint: disable=too-many-public-methods
         :param default_subject: Optional :attr:`~Message.subject`
            template/string to use, if config does not specify one.
 
+        :param fallback_key: Optional fallback :term:`email key` to
+           use for config/template lookup, if nothing is found for
+           ``key``.
+
         :param \\**kwargs: Any remaining kwargs are passed as-is to
            :meth:`make_message()`.  More on this below.
 
@@ -411,7 +483,7 @@ class EmailHandler(GenericHandler):  # pylint: disable=too-many-public-methods
             kwargs["sender"] = self.get_auto_sender(key)
         if "subject" not in kwargs:
             kwargs["subject"] = self.get_auto_subject(
-                key, context, default=default_subject
+                key, context, default=default_subject, fallback_key=fallback_key
             )
         if "to" not in kwargs:
             kwargs["to"] = self.get_auto_to(key)
@@ -420,11 +492,47 @@ class EmailHandler(GenericHandler):  # pylint: disable=too-many-public-methods
         if "bcc" not in kwargs:
             kwargs["bcc"] = self.get_auto_bcc(key)
         if "txt_body" not in kwargs:
-            kwargs["txt_body"] = self.get_auto_txt_body(key, context)
+            kwargs["txt_body"] = self.get_auto_txt_body(
+                key, context, fallback_key=fallback_key
+            )
         if "html_body" not in kwargs:
-            kwargs["html_body"] = self.get_auto_html_body(key, context)
+            kwargs["html_body"] = self.get_auto_html_body(
+                key, context, fallback_key=fallback_key
+            )
         return self.make_message(**kwargs)
 
+    def get_email_context(self, key, context=None):  # pylint: disable=unused-argument
+        """
+        This must return the "full" context for rendering the email
+        subject and/or body templates.
+
+        Normally the input ``context`` is coming from the
+        :meth:`send_email()` param of the same name.
+
+        By default, this method modifies the input context to add the
+        following:
+
+        * ``config`` - reference to the :term:`config object`
+        * ``app`` - reference to the :term:`app handler`
+
+        Subclass may further modify as needed.
+
+        :param key: The :term:`email key` for which to get context.
+
+        :param context: Input context dict.
+
+        :returns: Final context dict
+        """
+        if context is None:
+            context = {}
+        context.update(
+            {
+                "config": self.config,
+                "app": self.app,
+            }
+        )
+        return context
+
     def get_auto_sender(self, key):
         """
         Returns automatic
@@ -455,7 +563,13 @@ class EmailHandler(GenericHandler):  # pylint: disable=too-many-public-methods
         return self.config.get(f"{self.config.appname}.email.default.replyto")
 
     def get_auto_subject(  # pylint: disable=too-many-arguments,too-many-positional-arguments
-        self, key, context=None, rendered=True, setting=None, default=None
+        self,
+        key,
+        context=None,
+        rendered=True,
+        setting=None,
+        default=None,
+        fallback_key=None,
     ):
         """
         Returns automatic :attr:`~wuttjamaican.email.Message.subject`
@@ -464,7 +578,8 @@ class EmailHandler(GenericHandler):  # pylint: disable=too-many-public-methods
         This calls :meth:`get_auto_subject_template()` and then
         (usually) renders the result using the given context.
 
-        :param key: Key for the :term:`email type`.
+        :param key: Key for the :term:`email type`.  See also the
+           ``fallback_key`` param, below.
 
         :param context: Dict of context for rendering the subject
            template, if applicable.
@@ -479,16 +594,23 @@ class EmailHandler(GenericHandler):  # pylint: disable=too-many-public-methods
 
         :param default: Default subject to use if none is configured.
 
+        :param fallback_key: Optional fallback :term:`email key` to
+           use for config lookup, if nothing is found for ``key``.
+
         :returns: Final subject text, either "raw" or rendered.
         """
-        template = self.get_auto_subject_template(key, setting=setting, default=default)
+        template = self.get_auto_subject_template(
+            key, setting=setting, default=default, fallback_key=fallback_key
+        )
         if not rendered:
             return template
 
-        context = context or {}
+        context = self.get_email_context(key, context)
         return Template(template).render(**context)
 
-    def get_auto_subject_template(self, key, setting=None, default=None):
+    def get_auto_subject_template(
+        self, key, setting=None, default=None, fallback_key=None
+    ):
         """
         Returns the template string to use for automatic subject line
         of a message, as determined by config.
@@ -509,22 +631,32 @@ class EmailHandler(GenericHandler):  # pylint: disable=too-many-public-methods
 
         :param default: Default subject to use if none is configured.
 
+        :param fallback_key: Optional fallback :term:`email key` to
+           use for config lookup, if nothing is found for ``key``.
+
         :returns: Final subject template, as raw text.
         """
         # prefer configured subject specific to key
-        template = self.config.get(f"{self.config.appname}.email.{key}.subject")
-        if template:
+        if template := self.config.get(f"{self.config.appname}.email.{key}.subject"):
             return template
 
         # or use caller-specified default, if applicable
         if default:
             return default
 
+        # or use fallback key, if provided
+        if fallback_key:
+            if template := self.config.get(
+                f"{self.config.appname}.email.{fallback_key}.subject"
+            ):
+                return template
+
         # or subject from email setting, if defined
         if not setting:
             setting = self.get_email_setting(key)
-        if setting and setting.default_subject:
-            return setting.default_subject
+        if setting:
+            if subject := setting.get_default_subject():
+                return subject
 
         # fall back to global default
         return self.config.get(
@@ -569,32 +701,34 @@ class EmailHandler(GenericHandler):  # pylint: disable=too-many-public-methods
             f"{self.config.appname}.email.default.{typ}", default=[]
         )
 
-    def get_auto_txt_body(self, key, context=None):
+    def get_auto_txt_body(self, key, context=None, fallback_key=None):
         """
         Returns automatic :attr:`~wuttjamaican.email.Message.txt_body`
         content for a message, as determined by config.  This renders
         a template with the given context.
         """
-        template = self.get_auto_body_template(key, "txt")
+        template = self.get_auto_body_template(key, "txt", fallback_key=fallback_key)
         if template:
-            context = context or {}
+            context = self.get_email_context(key, context)
             return template.render(**context)
         return None
 
-    def get_auto_html_body(self, key, context=None):
+    def get_auto_html_body(self, key, context=None, fallback_key=None):
         """
         Returns automatic
         :attr:`~wuttjamaican.email.Message.html_body` content for a
         message, as determined by config.  This renders a template
         with the given context.
         """
-        template = self.get_auto_body_template(key, "html")
+        template = self.get_auto_body_template(key, "html", fallback_key=fallback_key)
         if template:
-            context = context or {}
+            context = self.get_email_context(key, context)
             return template.render(**context)
         return None
 
-    def get_auto_body_template(self, key, mode):  # pylint: disable=empty-docstring
+    def get_auto_body_template(  # pylint: disable=empty-docstring
+        self, key, mode, fallback_key=None
+    ):
         """ """
         mode = mode.lower()
         if mode == "txt":
@@ -605,9 +739,19 @@ class EmailHandler(GenericHandler):  # pylint: disable=too-many-public-methods
             raise ValueError("requested mode not supported")
 
         try:
+
+            # prefer specific template for key
             return templates.get_template(f"{key}.{mode}.mako")
+
+        except TopLevelLookupException:
+
+            # but can use fallback if applicable
+            if fallback_key:
+                try:
+                    return templates.get_template(f"{fallback_key}.{mode}.mako")
                 except TopLevelLookupException:
                     pass
+
         return None
 
     def get_notes(self, key):
@@ -756,7 +900,14 @@ class EmailHandler(GenericHandler):  # pylint: disable=too-many-public-methods
         )
 
     def send_email(  # pylint: disable=too-many-arguments,too-many-positional-arguments
-        self, key=None, context=None, message=None, sender=None, recips=None, **kwargs
+        self,
+        key=None,
+        context=None,
+        message=None,
+        sender=None,
+        recips=None,
+        fallback_key=None,
+        **kwargs,
     ):
         """
         Send an email message.
@@ -773,6 +924,7 @@ class EmailHandler(GenericHandler):  # pylint: disable=too-many-public-methods
         :param key: When auto-creating a message, this is the
            :term:`email key` identifying the type of email to send.
            Used to lookup config settings and template files.
+           See also the ``fallback_key`` param, below.
 
         :param context: Context dict for rendering automatic email
            template(s).
@@ -812,6 +964,10 @@ class EmailHandler(GenericHandler):  # pylint: disable=too-many-public-methods
                  context = {'data': [1, 2, 3]}
                  app.send_email('foo', context, to='me@example.com', cc='bobby@example.com')
 
+        :param fallback_key: Optional fallback :term:`email key` to
+           use for config/template lookup, if nothing is found for
+           ``key``.
+
         :param \\**kwargs: Any remaining kwargs are passed along to
            :meth:`make_auto_message()`.  So, not used if you provide
            the ``message``.
@@ -827,7 +983,9 @@ class EmailHandler(GenericHandler):  # pylint: disable=too-many-public-methods
             # auto-create message from key + context
             if sender:
                 kwargs["sender"] = sender
-            message = self.make_auto_message(key, context or {}, **kwargs)
+            message = self.make_auto_message(
+                key, context or {}, fallback_key=fallback_key, **kwargs
+            )
             if not (message.txt_body or message.html_body):
                 raise RuntimeError(
                     f"message (type: {key}) has no body - "

src/wuttjamaican/templates/diff.mako

@@ -0,0 +1,15 @@
+## -*- coding: utf-8; -*-
+<table border="1" style="border-collapse: collapse;">
+  <thead>
+    <tr>
+      % for column in diff.columns:
+          <th style="padding: 0.25rem;">${column}</th>
+      % endfor
+    </tr>
+  </thead>
+  <tbody>
+    % for field in diff.fields:
+       ${diff.render_field_row(field)}
+    % endfor
+  </tbody>
+</table>

tests/test_app.py

@@ -672,6 +672,14 @@ app_title = WuttaTest
         self.assertEqual(self.app.render_quantity(0), "0")
         self.assertEqual(self.app.render_quantity(0, empty_zero=True), "")
 
+        # has thousands separator
+        value = 1234
+        self.assertEqual(self.app.render_quantity(value), "1,234")
+        value = decimal.Decimal("1234.567")
+        self.assertEqual(self.app.render_quantity(value), "1,234.567")
+        value = decimal.Decimal("1234.567000")
+        self.assertEqual(self.app.render_quantity(value), "1,234.567")
+
     def test_render_time_ago(self):
         with patch.object(mod, "humanize") as humanize:
             humanize.naturaltime.return_value = "now"

tests/test_diffs.py

@@ -0,0 +1,144 @@
+# -*- coding: utf-8; -*-
+
+from wuttjamaican import diffs as mod
+from wuttjamaican.testing import ConfigTestCase
+
+
+class TestDiff(ConfigTestCase):
+
+    def make_diff(self, *args, **kwargs):
+        return mod.Diff(self.config, *args, **kwargs)
+
+    def test_constructor(self):
+        old_data = {"foo": "bar"}
+        new_data = {"foo": "baz"}
+        diff = self.make_diff(old_data, new_data, fields=["foo"])
+        self.assertEqual(diff.fields, ["foo"])
+        self.assertEqual(diff.cell_padding, "0.25rem")
+        diff = self.make_diff(old_data, new_data, cell_padding="0.5rem")
+        self.assertEqual(diff.cell_padding, "0.5rem")
+
+    def test_make_fields(self):
+        old_data = {"foo": "bar"}
+        new_data = {"foo": "bar", "baz": "zer"}
+        # nb. this calls make_fields()
+        diff = self.make_diff(old_data, new_data)
+        # TODO: should the fields be cumulative? or just use new_data?
+        self.assertEqual(diff.fields, ["baz", "foo"])
+
+    def test_values(self):
+        old_data = {"foo": "bar"}
+        new_data = {"foo": "baz"}
+        diff = self.make_diff(old_data, new_data)
+        self.assertEqual(diff.old_value("foo"), "bar")
+        self.assertEqual(diff.new_value("foo"), "baz")
+
+    def test_values_differ(self):
+        old_data = {"foo": "bar"}
+        new_data = {"foo": "baz"}
+        diff = self.make_diff(old_data, new_data)
+        self.assertTrue(diff.values_differ("foo"))
+
+        old_data = {"foo": "bar"}
+        new_data = {"foo": "bar"}
+        diff = self.make_diff(old_data, new_data)
+        self.assertFalse(diff.values_differ("foo"))
+
+    def test_render_values(self):
+        old_data = {"foo": "bar"}
+        new_data = {"foo": "baz"}
+        diff = self.make_diff(old_data, new_data)
+        self.assertEqual(
+            diff.render_old_value("foo"),
+            '<span style="font-family: monospace;">&#39;bar&#39;</span>',
+        )
+        self.assertEqual(
+            diff.render_new_value("foo"),
+            '<span style="font-family: monospace;">&#39;baz&#39;</span>',
+        )
+
+    def test_get_old_value_attrs(self):
+
+        # no change
+        old_data = {"foo": "bar"}
+        new_data = {"foo": "bar"}
+        diff = self.make_diff(old_data, new_data, nature="update")
+        self.assertEqual(diff.get_old_value_attrs(False), {"style": "padding: 0.25rem"})
+
+        # update
+        old_data = {"foo": "bar"}
+        new_data = {"foo": "baz"}
+        diff = self.make_diff(old_data, new_data, nature="update")
+        self.assertEqual(
+            diff.get_old_value_attrs(True),
+            {"style": f"background-color: {diff.old_color}; padding: 0.25rem"},
+        )
+
+        # delete
+        old_data = {"foo": "bar"}
+        new_data = {}
+        diff = self.make_diff(old_data, new_data, nature="delete")
+        self.assertEqual(
+            diff.get_old_value_attrs(True),
+            {"style": f"background-color: {diff.old_color}; padding: 0.25rem"},
+        )
+
+    def test_get_new_value_attrs(self):
+
+        # no change
+        old_data = {"foo": "bar"}
+        new_data = {"foo": "bar"}
+        diff = self.make_diff(old_data, new_data, nature="update")
+        self.assertEqual(diff.get_new_value_attrs(False), {"style": "padding: 0.25rem"})
+
+        # update
+        old_data = {"foo": "bar"}
+        new_data = {"foo": "baz"}
+        diff = self.make_diff(old_data, new_data, nature="update")
+        self.assertEqual(
+            diff.get_new_value_attrs(True),
+            {"style": f"background-color: {diff.new_color}; padding: 0.25rem"},
+        )
+
+        # create
+        old_data = {}
+        new_data = {"foo": "bar"}
+        diff = self.make_diff(old_data, new_data, nature="create")
+        self.assertEqual(
+            diff.get_new_value_attrs(True),
+            {"style": f"background-color: {diff.new_color}; padding: 0.25rem"},
+        )
+
+    def test_render_field_row(self):
+        old_data = {"foo": "bar"}
+        new_data = {"foo": "baz"}
+        diff = self.make_diff(old_data, new_data)
+        row = diff.render_field_row("foo")
+        self.assertIn("<tr>", row)
+        self.assertIn("&#39;bar&#39;", row)
+        self.assertIn(
+            f'style="background-color: {diff.old_color}; padding: 0.25rem"', row
+        )
+        self.assertIn("&#39;baz&#39;", row)
+        self.assertIn(
+            f'style="background-color: {diff.new_color}; padding: 0.25rem"', row
+        )
+        self.assertIn("</tr>", row)
+
+    def test_render_html(self):
+        old_data = {"foo": "bar"}
+        new_data = {"foo": "baz"}
+        diff = self.make_diff(old_data, new_data)
+        html = diff.render_html()
+        self.assertIn("<table", html)
+        self.assertIn("<tr>", html)
+        self.assertIn("&#39;bar&#39;", html)
+        self.assertIn(
+            f'style="background-color: {diff.old_color}; padding: 0.25rem"', html
+        )
+        self.assertIn("&#39;baz&#39;", html)
+        self.assertIn(
+            f'style="background-color: {diff.new_color}; padding: 0.25rem"', html
+        )
+        self.assertIn("</tr>", html)
+        self.assertIn("</table>", html)

tests/test_email.py

@@ -5,6 +5,7 @@ from unittest import TestCase
 from unittest.mock import patch, MagicMock
 
 import pytest
+from mako.template import Template
 
 from wuttjamaican import email as mod
 from wuttjamaican.util import resource_path
@@ -20,6 +21,16 @@ class TestEmailSetting(ConfigTestCase):
         self.assertIs(setting.app, self.app)
         self.assertEqual(setting.key, "EmailSetting")
 
+    def test_get_description(self):
+
+        class MockSetting(mod.EmailSetting):
+            """
+            this should be a good test
+            """
+
+        setting = MockSetting(self.config)
+        self.assertEqual(setting.get_description(), "this should be a good test")
+
     def test_sample_data(self):
         setting = mod.EmailSetting(self.config)
         self.assertEqual(setting.sample_data(), {})
@@ -299,7 +310,9 @@ class TestEmailHandler(ConfigTestCase):
             msg = handler.make_auto_message("foo", subject=None)
             get_auto_subject.assert_not_called()
             msg = handler.make_auto_message("foo")
-            get_auto_subject.assert_called_once_with("foo", {}, default=None)
+            get_auto_subject.assert_called_once_with(
+                "foo", {}, default=None, fallback_key=None
+            )
 
         # to
         with patch.object(handler, "get_auto_to") as get_auto_to:
@@ -330,14 +343,18 @@ class TestEmailHandler(ConfigTestCase):
             msg = handler.make_auto_message("foo", txt_body=None)
             get_auto_txt_body.assert_not_called()
             msg = handler.make_auto_message("foo")
-            get_auto_txt_body.assert_called_once_with("foo", {})
+            get_auto_txt_body.assert_called_once_with(
+                "foo", {"config": self.config, "app": self.app}, fallback_key=None
+            )
 
         # html_body
         with patch.object(handler, "get_auto_html_body") as get_auto_html_body:
             msg = handler.make_auto_message("foo", html_body=None)
             get_auto_html_body.assert_not_called()
             msg = handler.make_auto_message("foo")
-            get_auto_html_body.assert_called_once_with("foo", {})
+            get_auto_html_body.assert_called_once_with(
+                "foo", {"config": self.config, "app": self.app}, fallback_key=None
+            )
 
     def test_get_auto_sender(self):
         handler = self.make_handler()
@@ -384,6 +401,11 @@ class TestEmailHandler(ConfigTestCase):
         template = handler.get_auto_subject_template("foo")
         self.assertEqual(template, "Foo Message")
 
+        # can configure via fallback_key
+        self.config.setdefault("wutta.email.bar.subject", "Bar Message")
+        template = handler.get_auto_subject_template("baz", fallback_key="bar")
+        self.assertEqual(template, "Bar Message")
+
         # EmailSetting can provide default subject
         providers = {
             "wuttatest": MagicMock(email_modules=["tests.test_email"]),
@@ -446,27 +468,49 @@ class TestEmailHandler(ConfigTestCase):
         self.assertEqual(recips, ["bob@example.com"])
 
     def test_get_auto_body_template(self):
-        from mako.template import Template
-
         handler = self.make_handler()
 
-        # error if bad request
-        self.assertRaises(ValueError, handler.get_auto_body_template, "foo", "BADTYPE")
+        # error if invalid mode (must be 'html' or 'txt')
+        self.assertRaises(ValueError, handler.get_auto_body_template, "foo", "BAD_MODE")
 
-        # empty by default
-        template = handler.get_auto_body_template("foo", "txt")
-        self.assertIsNone(template)
+        # no template by default
+        self.assertIsNone(handler.get_auto_body_template("foo", "html"))
+        self.assertIsNone(handler.get_auto_body_template("foo", "txt"))
 
-        # but returns a template if it exists
+        # mock template lookup
         providers = {
             "wuttatest": MagicMock(email_templates=["tests:email-templates"]),
         }
         with patch.object(self.app, "providers", new=providers):
             handler = self.make_handler()
+
+            # template exists (txt)
             template = handler.get_auto_body_template("test_foo", "txt")
             self.assertIsInstance(template, Template)
             self.assertEqual(template.uri, "test_foo.txt.mako")
 
+            # template exists (html)
+            template = handler.get_auto_body_template("test_foo", "html")
+            self.assertIsInstance(template, Template)
+            self.assertEqual(template.uri, "test_foo.html.mako")
+
+            # no such template
+            template = handler.get_auto_body_template("no_such_template", "html")
+            self.assertIsNone(template)
+
+            # but can use fallback
+            template = handler.get_auto_body_template(
+                "no_such_template", "html", fallback_key="test_foo"
+            )
+            self.assertIsInstance(template, Template)
+            self.assertEqual(template.uri, "test_foo.html.mako")
+
+            # what if fallback is also not found
+            template = handler.get_auto_body_template(
+                "no_such_template", "html", fallback_key="this_neither"
+            )
+            self.assertIsNone(template)
+
     def test_get_auto_txt_body(self):
         handler = self.make_handler()