Hotels: Fix relay/unused-fields in HotelDetailScreen

Refactor countBookingPrice function into HotelDetailScreen since it is
not used elsewhere anymore

app/hotels/src/singleHotel/HotelDetailScreen.js

@@ -1,7 +1,5 @@
 // @flow
 
-/* eslint-disable relay/unused-fields */
-// TODO: Fix ^^
 import * as React from 'react';
 import { ScrollView, View, Platform } from 'react-native';
 import {
@@ -32,7 +30,11 @@ import {
   type HotelsContextState,
   type ApiProvider,
 } from '../HotelsContext';
-import countBookingPrice from './bookNow/countBookingPrice';
+
+type Price = {|
+  +amount: number,
+  +currency: string,
+|};
 
 type PropsWithContext = {|
   ...Props,
@@ -86,10 +88,7 @@ export class HotelDetailScreen extends React.Component<
 
   componentDidUpdate(prevProps: PropsWithContext) {
     if (!isEqual(prevProps.selected, this.props.selected)) {
-      const price = countBookingPrice(
-        this.props.availableHotel?.availableRooms,
-        this.props.selected,
-      );
+      const price = this.countBookingPrice();
       if (price != null) {
         this.props.setPrice(price);
       }
@@ -100,6 +99,40 @@ export class HotelDetailScreen extends React.Component<
     this.props.reset();
   }
 
+  countBookingPrice = (): ?Price => {
+    const availableRooms = this.props.availableHotel?.availableRooms;
+    const selected = this.props.selected;
+
+    if (!availableRooms) {
+      return null;
+    }
+    const positiveSelections = Object.entries(selected).filter(
+      (selection: any) => selection[1] > 0,
+    );
+
+    if (positiveSelections.length === 0) {
+      return null;
+    }
+
+    const amount = positiveSelections
+      .map((selection: any) => {
+        const [id, count] = selection;
+
+        const room = availableRooms.find(room => room?.id === id);
+        return room?.incrementalPrice?.[count - 1]?.amount;
+      })
+      .reduce((a, b) => a + b, 0);
+
+    const currency =
+      availableRooms.find(room => room?.id === positiveSelections[0][0])
+        ?.incrementalPrice?.[0]?.currency ?? '';
+
+    return {
+      amount,
+      currency,
+    };
+  };
+
   isNarrowLayout = () => {
     return this.props.width < Device.DEVICE_THRESHOLD;
   };

app/hotels/src/singleHotel/HotelDetailScreenContext.js

@@ -31,24 +31,24 @@ type Props = {|
   +guestCount: number,
 |};
 
-type Money = {|
-  amount: number,
-  currency: string,
+type Price = {|
+  +amount: number,
+  +currency: string,
 |};
 
 type State = {|
   selected: {
     [string]: number, // originalId: count
   },
-  price: Money,
+  price: Price,
   maxPersons: number,
   numberOfRooms: number,
   +getPersonCount: () => number,
   +actions: {|
     +selectRoom: (id: string, maxPersons: number) => void,
     +deselectRoom: (id: string, maxPersons: number) => void,
     +reset: () => void,
-    +setPrice: (price: Money) => void,
+    +setPrice: (price: Price) => void,
   |},
 |};
 
@@ -107,7 +107,7 @@ export class Provider extends React.Component<Props, State> {
       : this.state.maxPersons;
   };
 
-  setPrice = (price: Money) => {
+  setPrice = (price: Price) => {
     this.setState({ price });
   };
 

app/hotels/src/singleHotel/__tests__/HotelDetailScreen.test.js

@@ -0,0 +1,102 @@
+// @flow
+
+import * as React from 'react';
+import renderer from 'react-test-renderer';
+
+import { HotelDetailScreen } from '../HotelDetailScreen';
+
+const $fragmentRefs: any = null;
+const availableRooms = [
+  {
+    $fragmentRefs,
+    id: 'aaa',
+    incrementalPrice: [
+      {
+        amount: 500,
+        currency: 'EUR',
+      },
+      {
+        amount: 1000,
+        currency: 'EUR',
+      },
+    ],
+  },
+  {
+    $fragmentRefs,
+    id: 'bbb',
+    incrementalPrice: [
+      {
+        amount: 333,
+        currency: 'EUR',
+      },
+      {
+        amount: 666,
+        currency: 'EUR',
+      },
+    ],
+  },
+];
+
+const getComponent = (availableRooms, selected) => {
+  // $FlowExpectedError: Passing just props needed to perform test
+  return new HotelDetailScreen({
+    availableHotel: {
+      availableRooms,
+    },
+    selected,
+  });
+};
+
+describe('countBookingPrice', () => {
+  it('returns null when availableRooms are not provided', () => {
+    const NullComponent = getComponent(null, { aaa: 1 });
+
+    const UndefinedComponent = getComponent(null, { aaa: 1 });
+
+    expect(NullComponent.countBookingPrice()).toBe(null);
+    expect(UndefinedComponent.countBookingPrice()).toBe(null);
+  });
+
+  it('returns null when no room is selected', () => {
+    const ComponentA = getComponent(availableRooms, {});
+    const ComponentB = getComponent(availableRooms, { aaa: 0, bbb: 0 });
+
+    expect(ComponentA.countBookingPrice()).toBe(null);
+    expect(ComponentB.countBookingPrice()).toBe(null);
+  });
+
+  it('returns sum of selected rooms', () => {
+    const Component = getComponent(availableRooms, { aaa: 2, bbb: 1 });
+
+    expect(Component.countBookingPrice()).toEqual({
+      amount: 1333,
+      currency: 'EUR',
+    });
+  });
+
+  it('takes a currency from the first selected room', () => {
+    const czechRooms = [
+      {
+        $fragmentRefs,
+        id: 'aaa',
+        incrementalPrice: [],
+      },
+      {
+        $fragmentRefs,
+        id: 'bbb',
+        incrementalPrice: [
+          {
+            amount: 123,
+            currency: 'CZK',
+          },
+        ],
+      },
+    ];
+    const Component = getComponent(czechRooms, { bbb: 1 });
+
+    expect(Component.countBookingPrice()).toEqual({
+      amount: 123,
+      currency: 'CZK',
+    });
+  });
+});