feat: update firestore listener when props change (#10)

* Adds componentWillReceiveProps lifecycle method; adds tests

* Just resets `isLoading` state; wraps unsubscribe in an if, following the unmount lifecycle pattern

* WIP: updating tests for full coverage

* Finishes updating tests

* Adds lodash.isEqual for deep equality check

* Finishes adding tests

* Removes lodash dependency in favor of custom array comparison helper

src/FirestoreCollection.js

@@ -1,5 +1,6 @@
 import { Component } from 'react';
 import PropTypes from 'prop-types';
+import deepEqual from './utils/deepEqual';
 
 class FirestoreCollection extends Component {
   static propTypes = {
@@ -29,6 +30,25 @@ class FirestoreCollection extends Component {
   }
 
   componentWillUnmount() {
+    this.handleUnsubscribe();
+  }
+
+  componentWillReceiveProps(nextProps) {
+    if (
+      nextProps.path !== this.props.path ||
+      nextProps.sort !== this.props.sort ||
+      nextProps.limit !== this.props.limit ||
+      !deepEqual(nextProps.filter, this.props.filter)
+    ) {
+      this.handleUnsubscribe();
+
+      this.setState({ isLoading: true }, () =>
+        this.setupFirestoreListener(this.props),
+      );
+    }
+  }
+
+  handleUnsubscribe() {
     if (this.unsubscribe) {
       this.unsubscribe();
     }

src/FirestoreDocument.js

@@ -23,6 +23,20 @@ class FirestoreDocument extends Component {
   }
 
   componentWillUnmount() {
+    this.handleUnsubscribe();
+  }
+
+  componentWillReceiveProps(nextProps) {
+    if (nextProps.path !== this.props.path) {
+      this.handleUnsubscribe();
+
+      this.setState({ isLoading: true }, () =>
+        this.setupFirestoreListener(this.props),
+      );
+    }
+  }
+
+  handleUnsubscribe() {
     if (this.unsubscribe) {
       this.unsubscribe();
     }