cli: Add support for loading template variables from json

Author: jackrosenthal

kajiki/__main__.py

@@ -1,7 +1,9 @@
 """Command-line interface to Kajiki to render a single template."""
 
 import argparse
+import json
 import os
+import pathlib
 import site
 import sys
 
@@ -51,6 +53,13 @@ def main(argv=None):
         metavar="KEY=VALUE",
         help="Template variables, passed as KEY=VALUE pairs.",
     )
+    parser.add_argument(
+        "--json",
+        action="append",
+        default=[],
+        type=pathlib.Path,
+        help="Load template variables from a JSON file.",
+    )
     parser.add_argument(
         "-p",
         "--package",
@@ -82,9 +91,16 @@ def main(argv=None):
         opts.paths.append(os.path.dirname(opts.file_or_package) or ".")
         loader_kwargs["path"] = opts.paths
 
+    template_variables = {}
+    for json_file in opts.json:
+        with json_file.open("r", encoding="utf-8") as f:
+            template_variables.update(json.load(f))
+
+    template_variables.update(dict(opts.template_variables))
+
     loader = opts.loader_type(force_mode=opts.force_mode, **loader_kwargs)
     template = loader.import_(opts.file_or_package)
-    result = template(dict(opts.template_variables)).render()
+    result = template(template_variables).render()
     opts.output_file.write(result)
 
     # Close the output file to avoid a ResourceWarning during unit

tests/test_cli.py

@@ -133,3 +133,19 @@ def test_template_variables_bad(capsys):
     captured = capsys.readouterr()
     assert captured.out == ""
     assert captured.err.endswith("error: argument -v/--var: Expected a KEY=VALUE pair, got BADBADBAD\n")
+
+
+def test_json_template_variables(tmp_path, main_mocks):
+    json_file = tmp_path / "json_file.json"
+    json_file.write_text('{"foo": "bar", "baz": "bip"}')
+    main(["--json", str(json_file), "infile.txt"])
+
+    main_mocks.file_loader_type.assert_called_once_with(path=["."], force_mode=None)
+    main_mocks.import_.assert_called_once_with("infile.txt")
+    main_mocks.template_type.assert_called_once_with(
+        {
+            "foo": "bar",
+            "baz": "bip",
+        }
+    )
+    main_mocks.render.assert_called_once_with()