Refactor --template code (#1711)

* Move path concerns to path.py and template concerns to editor.py -- BDD tests are failing
* Move path-related constants from config.py to path.py
* Mock get_templates_path in its new calling file
* Mediate template arg vs. config in controller then read template text in editor and unify those two use cases.
Some tests still failing
* Fix test whose message had changed
* poe format
* Refactor for easier unit testing and add unit tests
* Use path strings instead of Path objects in return values to prevent side effects that caused unit tests to fail on some platforms
* poe format
* Attempt to bypass getcwd errors in CI with patch
* Consistently use strings for paths instead of some strings and some pathlib.Path
* Keep pathlib within a function for readability
* fix for ruamel.yaml versions >=0.17.22
* Run poe format

---------

Co-authored-by: Jonathan Wren <jonathan@nowandwren.com>

jrnl/editor.py

@@ -15,6 +15,8 @@ from jrnl.messages import MsgText
 from jrnl.os_compat import on_windows
 from jrnl.os_compat import split_args
 from jrnl.output import print_msg
+from jrnl.path import absolute_path
+from jrnl.path import get_templates_path
 
 
 def get_text_from_editor(config: dict, template: str = "") -> str:
@@ -73,3 +75,46 @@ def get_text_from_stdin() -> str:
         )
 
     return raw
+
+
+def get_template_path(template_path: str, jrnl_template_dir: str) -> str:
+    actual_template_path = os.path.join(jrnl_template_dir, template_path)
+    if not os.path.exists(actual_template_path):
+        logging.debug(
+            f"Couldn't open {actual_template_path}. Treating template path like a local / abs path."
+        )
+        actual_template_path = absolute_path(template_path)
+
+    return actual_template_path
+
+
+def read_template_file(template_path: str) -> str:
+    """
+    Reads the template file given a template path in this order:
+
+        * Check $XDG_DATA_HOME/jrnl/templates/template_path.
+        * Check template_arg as an absolute / relative path.
+
+    If a file is found, its contents are returned as a string.
+    If not, a JrnlException is raised.
+    """
+
+    jrnl_template_dir = get_templates_path()
+    actual_template_path = get_template_path(template_path, jrnl_template_dir)
+
+    try:
+        with open(actual_template_path, encoding="utf-8") as f:
+            template_data = f.read()
+            return template_data
+    except FileNotFoundError:
+        raise JrnlException(
+            Message(
+                MsgText.CantReadTemplate,
+                MsgStyle.ERROR,
+                {
+                    "template_path": template_path,
+                    "actual_template_path": actual_template_path,
+                    "jrnl_template_dir": str(jrnl_template_dir) + os.sep,
+                },
+            )
+        )