doesn't support pure component

packages/mobx-react/__tests__/observer.test.tsx

@@ -563,7 +563,7 @@ test("it rerenders correctly if some props are non-observables - 2", () => {
     let odata = observable({ x: 1 })
 
     @observer
-    class Component extends React.PureComponent<any, any> {
+    class Component extends React.Component<any, any> {
         @computed
         get computed() {
             return this.props.data.y // should recompute, since props.data is changed
@@ -756,26 +756,6 @@ describe("use Observer inject and render sugar should work  ", () => {
     })
 })
 
-test("use PureComponent", () => {
-    const msg: Array<any> = []
-    const baseWarn = console.warn
-    console.warn = m => msg.push(m)
-
-    try {
-        observer(
-            class X extends React.PureComponent {
-                render() {
-                    return <div />
-                }
-            }
-        )
-
-        expect(msg).toEqual([])
-    } finally {
-        console.warn = baseWarn
-    }
-})
-
 test("static on function components are hoisted", () => {
     const Comp = () => <div />
     Comp.foo = 3

packages/mobx-react/src/observerClass.ts

@@ -97,6 +97,8 @@ export function makeClassComponentObserver(
                 "It is not allowed to use shouldComponentUpdate in observer based components."
             )
         }
+    } else {
+        throw new Error("It is not allowed to use observer on PureComponent.")
     }
 
     // this.props and this.state are made observable, just to make sure @computed fields that