fix(oas3): attempt to render schemas not resolved by swagger-client (#9629)

Refs #9513

test/unit/core/plugins/oas3/selectors.js

@@ -0,0 +1,62 @@
+/**
+ * @prettier
+ */
+import { fromJS } from "immutable"
+import { findSchema } from "core/plugins/oas3/spec-extensions/selectors"
+
+describe("findSchema", function () {
+  const state = fromJS({
+    resolvedSubtrees: {
+      components: {
+        schemas: {
+          resolvedSchema: {
+            type: "object",
+            properties: {
+              name: {
+                type: "string",
+              },
+            },
+          },
+        },
+      },
+    },
+    json: {
+      components: {
+        schemas: {
+          unresolvedSchema: {
+            $ref: "#/components/schemas/resolvedSchema",
+          },
+          resolvedSchema: {
+            type: "object",
+            properties: {
+              name: {
+                type: "string",
+              },
+            },
+          },
+        },
+      },
+    },
+  })
+
+  it("should get an unresolved schema", function () {
+    const result = findSchema(state, "unresolvedSchema")
+
+    expect(result).toEqual(
+      state.getIn(["json", "components", "schemas", "unresolvedSchema"])
+    )
+  })
+
+  it("should get a resolved schema", function () {
+    const result = findSchema(state, "resolvedSchema")
+
+    expect(result).toEqual(
+      state.getIn([
+        "resolvedSubtrees",
+        "components",
+        "schemas",
+        "resolvedSchema",
+      ])
+    )
+  })
+})