Autogenerate config marshal and unmarshal test with datagen

.chloggen/12906.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. receiver/otlp)
+component: cmd/mdatagen
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Add generated config marshal/unmarshal tests to mdatagen"
+
+# One or more tracking issues or pull requests related to the change
+issues: [12906]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

cmd/mdatagen/internal/sampleconnector/metadata.yaml

@@ -20,6 +20,13 @@ status:
   warnings:
     - Any additional information that should be brought to the consumer's attention
 
+tests:
+  invalid_configs:
+    - name: unknown_field
+      config:
+        unknown_field: value
+      error: "has invalid keys: unknown_field"
+
 resource_attributes:
   map.resource.attr:
     description: Resource attribute with a map value.