Add logic to load tools from json and validate

bagel/tool.py

@@ -2,6 +2,9 @@
 
 
 class Tool(NamedTuple):
+    """
+    A tool that can run against compatible benchmarks.
+    """
     name: str
     version: str
     benchmarks: Iterable[str]
@@ -12,8 +15,72 @@ def __str__(self) -> str:
 
 
 def load_tool(file: IO) -> Tool:
-    pass
+    """
+    Load a tool metadata object from its JSON file. Raises a ``ValueError``
+    if the object is malformed in any way. Use ``validate_tool`` to get
+    more information about an error.
 
+    TODO Adjust file paths to be relative to the metadata file location
+    """
+    import json
 
-def validate_tool(file: Union[IO, Dict]) -> List[str]:
-    pass
+    try:
+        tool_meta = json.load(file)
+        return Tool(**tool_meta)
+    except:
+        raise ValueError()
+
+
+def validate_tool(data: Union[IO, Dict]) -> List[str]:
+    """
+    Validate a tool metadata object in JSON format or a pre-loaded
+    dictionary. This includes verifying that all required fields exist and that
+    they are of the correct types.
+    """
+    import json
+    from json.decoder import JSONDecodeError
+
+    if isinstance(data, dict):
+        tool_meta = data
+    else:
+        try:
+            tool_meta = json.load(data)
+        except JSONDecodeError as err:
+            return [f"invalid JSON object: line {err.lineno}"]
+
+    if not isinstance(tool_meta, dict):
+        return [f"invalid JSON object: type is {type(tool_meta)}"]
+
+    fields = [
+        ("name", str),
+        ("version", str),
+        ("families", list),
+        ("image", str),
+        ("results", dict),
+    ]
+
+    msgs = []
+
+    for key, dt in fields:
+        if key not in tool_meta:
+            msgs.append(f"required field not found: {key}")
+            continue
+        if not isinstance(tool_meta[key], dt):
+            msgs.append(f"incorrect field type ({type(tool_meta[key])}): {key}")
+
+    if msgs:
+        return msgs
+
+    for bmark_family in tool_meta["families"]:
+        if not isinstance(bmark_family, str):
+            msgs.append(
+                f"incorrect benchmark family type ({type(bmark_family)}): {bmark_family}"
+            )
+
+    for key, value in tool_meta["results"].items():
+        if not isinstance(key, str):
+            msgs.append(f"incorrect results key type ({type(key)}): {key}")
+        if not isinstance(value, str):
+            msgs.append(f"incorrect results value type ({type(value)}): {key}")
+
+    return msgs