feat: Add output_path property, and streamline implementation (#50)

## About

Users got confused about the semantics of the `output_path_prefix`
property. This patch makes it better by renaming it to `output_path`,
while still providing backwards-compatibility.

Further, the `destination_path` property can also be used, thus this
target can be a drop-in replacement to the `hotgluexyz` variant.

The value of the variable does not need to be configured using a
trailing slash any longer. Instead, the implementation more thoroughly
leverages `pathlib.Path` for concatenating `output_path` and `filename`.

## References

- GH-9

## Thoughts

I am not sure about fc54324. I added it because mypy tripped like
described in the commit message. Please educate me if that was wrong, so
I will either remove it or amend it correspondingly.

README.md

@@ -12,7 +12,7 @@ Built with the [Meltano SDK](https://sdk.meltano.com) for Singer Taps and Target
 
 | Setting                  | Required | Default | Description |
 |:-------------------------|:--------:|:-------:|:------------|
-| output_path_prefix       | False    | None    | Optional path prefix which will be prepended to the file path indicated by `file_naming_schema`. |
+| output_path              | False    | None    | Filesystem path where to store output files. By default, the current working directory will be used. |
 | file_naming_scheme       | False    | {stream_name}.csv    | The scheme with which output files will be named. Naming scheme may leverage any of the following substitutions:<BR/>- `{stream_name}`<BR/>- `{datestamp}`<BR/>- `{timestamp}` |
 | datestamp_format         | False    | %Y-%m-%d | A python format string to use when outputting the `{datestamp}` string. For reference, see: https://docs.python.org/3/library/datetime.html#strftime-and-strptime-format-codes |
 | timestamp_format         | False    | %Y-%m-%d.T%H%M%S | A python format string to use when outputting the `{timestamp}` string. For reference, see: https://docs.python.org/3/library/datetime.html#strftime-and-strptime-format-codes |

meltano.yml

@@ -27,7 +27,7 @@ plugins:
     - catalog
     - discover
     settings:
-    - name: output_path_prefix
+    - name: output_path
       kind: string
     config:
-      output_path_prefix: ./.output/
+      output_path: ./.output

target_csv/sinks.py

@@ -2,11 +2,12 @@
 
 import datetime
 import sys
+import warnings
 from pathlib import Path
 from typing import Any, Dict, List, Optional
 
 import pytz
-from singer_sdk import PluginBase
+from singer_sdk import Target
 from singer_sdk.sinks import BatchSink
 
 from target_csv.serialization import write_csv
@@ -19,7 +20,7 @@ class CSVSink(BatchSink):
 
     def __init__(  # noqa: D107
         self,
-        target: PluginBase,
+        target: Target,
         stream_name: str,
         schema: Dict,
         key_properties: Optional[List[str]],
@@ -45,21 +46,40 @@ def filepath_replacement_map(self) -> Dict[str, str]:  # noqa: D102
         }
 
     @property
-    def destination_path(self) -> Path:  # noqa: D102
-        result = self.config["file_naming_scheme"]
+    def output_file(self) -> Path:  # noqa: D102
+        filename = self.config["file_naming_scheme"]
         for key, val in self.filepath_replacement_map.items():
             replacement_pattern = "{" f"{key}" "}"
-            if replacement_pattern in result:
-                result = result.replace(replacement_pattern, val)
+            if replacement_pattern in filename:
+                filename = filename.replace(replacement_pattern, val)
+
+        if "output_path_prefix" in self.config:
+            warnings.warn(
+                "The property `output_path_prefix` is deprecated, "
+                "please use `output_path`.",
+                category=UserWarning,
+            )
+
+        # Accept all possible properties defining the output path.
+        # - output_path: The new designated property.
+        # - destination_path: Alias for `output_path` (`hotgluexyz` compat).
+        # - output_path_prefix: The property used up until now.
+        output_path = self.config.get(
+            "output_path",
+            self.config.get(
+                "destination_path", self.config.get("output_path_prefix", None)
+            ),
+        )
 
-        if self.config.get("output_path_prefix", None) is not None:
-            result = f"{self.config['output_path_prefix']}{result}"
+        filepath = Path(filename)
+        if output_path is not None:
+            filepath = Path(output_path) / filepath
 
-        return Path(result)
+        return filepath
 
     def process_batch(self, context: dict) -> None:
         """Write out any prepped records and return once fully written."""
-        output_file: Path = self.destination_path
+        output_file: Path = self.output_file
         self.logger.info(f"Writing to destination file '{output_file.resolve()}'...")
         new_contents: dict  # noqa: F842
         create_new = (

target_csv/target.py

@@ -12,13 +12,26 @@ class TargetCSV(Target):
     name = "target-csv"
     config_jsonschema = th.PropertiesList(
         th.Property(
-            "output_path_prefix",
+            "output_path",
+            th.StringType,
+            description=(
+                "Filesystem path where to store output files. "
+                "By default, the current working directory will be used."
+            ),
+        ),
+        th.Property(
+            "destination_path",
             th.StringType,
             description=(
-                "Optional path prefix which will be prepended to "
-                "the file path indicated by `file_naming_schema`."
+                "Filesystem path where to store output files. Alias for "
+                "`output_path` to be compatible with the `hotgluexyz` variant."
             ),
         ),
+        th.Property(
+            "output_path_prefix",
+            th.StringType,
+            description=("DEPRECATED. Filesystem path where to store output files."),
+        ),
         th.Property(
             "file_naming_scheme",
             th.StringType,