feat: create new rule to enforce array parameters format (#1338)

packages/core/src/rules/oas3/array-parameter-serialization.ts

@@ -0,0 +1,43 @@
+import { Oas3Rule, Oas3Visitor } from '../../visitors';
+import { isRef } from '../../ref-utils';
+import { Oas3_1Schema, Oas3Parameter } from '../../typings/openapi';
+
+export type ArrayParameterSerializationOptions = {
+  in?: string[];
+};
+
+export const ArrayParameterSerialization: Oas3Rule = (
+  options: ArrayParameterSerializationOptions
+): Oas3Visitor => {
+  return {
+    Parameter: {
+      leave(node: Oas3Parameter, ctx) {
+        if (!node.schema) {
+          return;
+        }
+        const schema = isRef(node.schema)
+          ? ctx.resolve<Oas3_1Schema>(node.schema).node
+          : (node.schema as Oas3_1Schema);
+
+        if (schema && shouldReportMissingStyleAndExplode(node, schema, options)) {
+          ctx.report({
+            message: `Parameter \`${node.name}\` should have \`style\` and \`explode \` fields`,
+            location: ctx.location,
+          });
+        }
+      },
+    },
+  };
+};
+
+function shouldReportMissingStyleAndExplode(
+  node: Oas3Parameter,
+  schema: Oas3_1Schema,
+  options: ArrayParameterSerializationOptions
+) {
+  return (
+    (schema.type === 'array' || schema.items || schema.prefixItems) &&
+    (node.style === undefined || node.explode === undefined) &&
+    (!options.in || (node.in && options.in?.includes(node.in)))
+  );
+}