renderers: test empty values

Related: iterative/vscode-dvc#1520

src/dvc_render/base.py

@@ -1,6 +1,6 @@
 import abc
 from pathlib import Path
-from typing import TYPE_CHECKING, Dict, Iterable, Union
+from typing import TYPE_CHECKING, Iterable, List, Union
 
 if TYPE_CHECKING:
     from os import PathLike
@@ -19,9 +19,11 @@ class Renderer(abc.ABC):
 
     EXTENSIONS: Iterable[str] = {}
 
-    def __init__(self, datapoints: Dict, name: str, **properties):
-        self.datapoints = datapoints
-        self.name = name
+    def __init__(
+        self, datapoints: List = None, name: str = None, **properties
+    ):
+        self.datapoints = datapoints or []
+        self.name = name or ""
         self.properties = properties
 
     @abc.abstractmethod

src/dvc_render/vega.py

@@ -1,5 +1,5 @@
 from copy import deepcopy
-from typing import Dict, List, Optional
+from typing import List, Optional
 
 from .base import Renderer
 from .exceptions import DvcRenderException
@@ -32,7 +32,7 @@ class VegaRenderer(Renderer):
 
     EXTENSIONS = {".yml", ".yaml", ".json", ".csv", ".tsv"}
 
-    def __init__(self, datapoints: Dict, name: str, **properties):
+    def __init__(self, datapoints: List, name: str, **properties):
         super().__init__(datapoints, name, **properties)
         self.template = get_template(
             self.properties.get("template", None),

tests/test_image.py

@@ -23,18 +23,27 @@ def test_matches(extension, matches):
     assert ImageRenderer.matches(filename, {}) == matches
 
 
-def test_render(tmp_dir):
+@pytest.mark.parametrize(
+    "datapoints,filename,expected_parts",
+    [
+        (
+            [
+                {
+                    "filename": "file.jpg",
+                    "rev": "workspace",
+                    "src": "workspace_file.jpg",
+                }
+            ],
+            "file.jpg",
+            ["<p>file.jpg</p>", '<img src="workspace_file.jpg">'],
+        ),
+        (None, None, []),
+    ],
+)
+def test_render(datapoints, filename, expected_parts, tmp_dir):
     tmp_dir.gen("workspace_file.jpg", b"content")
 
-    datapoints = [
-        {
-            "filename": "file.jpg",
-            "rev": "workspace",
-            "src": "workspace_file.jpg",
-        }
-    ]
-
-    html = ImageRenderer(datapoints, "file.jpg").generate_html()
+    html = ImageRenderer(datapoints, filename).generate_html()
 
-    assert "<p>file.jpg</p>" in html
-    assert '<img src="workspace_file.jpg">' in html
+    for part in expected_parts:
+        assert part in html

tests/test_vega.py

@@ -6,7 +6,17 @@
 from dvc_render.vega import BadTemplateError, VegaRenderer
 from dvc_render.vega_templates import NoFieldInDataError, Template
 
-# pylint: disable=missing-function-docstring
+# pylint: disable=missing-function-docstring, C1803
+
+
+def test_init_empty():
+    renderer = VegaRenderer(None, None)
+
+    assert renderer.datapoints == []
+    assert renderer.name == ""
+    assert renderer.properties == {}
+
+    renderer.partial_html()
 
 
 def test_choose_axes():