Add tests for FeedExtensions

jcoynel · Feb 6, 2021 · 483cf83 · 483cf83
1 parent cbe9e9f
commit 483cf83
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Showing 2 changed files with 124 additions and 5 deletions.
diff --git a/Sources/AppStoreReviews/FeedExtensions.swift b/Sources/AppStoreReviews/FeedExtensions.swift
@@ -5,13 +5,13 @@ extension Feed {
     public var firstPage: Page? { Page(links.first) }
     public var lastPage: Page? { Page(links.last) }
     public var previousPage: Page? {
-        guard let currentPage = currentPage, let firstPage = firstPage, currentPage == firstPage else {
+        guard let currentPage = currentPage, let firstPage = firstPage, currentPage.page > firstPage.page else {
             return nil
         }
         return Page(links.previous)
     }
     public var nextPage: Page? {
-        guard let currentPage = currentPage, let lastPage = lastPage, currentPage == lastPage else {
+        guard let currentPage = currentPage, let lastPage = lastPage, currentPage.page < lastPage.page else {
             return nil
         }
         return Page(links.next)

diff --git a/Tests/AppStoreReviewsTests/FeedExtensionsTests.swift b/Tests/AppStoreReviewsTests/FeedExtensionsTests.swift
@@ -2,11 +2,130 @@ import XCTest
 @testable import AppStoreReviews
 
 final class FeedExtensionsTests: XCTestCase {
-    func testTODO() {
-        #warning("Not implemented")
+    func testCurrentPageIsEqualToLinksCurrentPage() {
+        let feed = testFeed(
+            links: Feed.Links(
+                alternate: fakeLink,
+                current: exampleLink(123),
+                first: exampleLink(1),
+                last: exampleLink(200),
+                previous: exampleLink(122),
+                next: exampleLink(124)))
+
+        XCTAssertEqual(feed.currentPage, expectedPage(123))
+    }
+
+    func testFirstPageIsEqualToLinksFirstPage() {
+        let feed = testFeed(
+            links: Feed.Links(
+                alternate: fakeLink,
+                current: exampleLink(123),
+                first: exampleLink(1),
+                last: exampleLink(200),
+                previous: exampleLink(122),
+                next: exampleLink(124)))
+
+        XCTAssertEqual(feed.firstPage, expectedPage(1))
+    }
+
+    func testLastPageIsEqualToLinksLastPage() {
+        let feed = testFeed(
+            links: Feed.Links(
+                alternate: fakeLink,
+                current: exampleLink(123),
+                first: exampleLink(1),
+                last: exampleLink(200),
+                previous: exampleLink(122),
+                next: exampleLink(124)))
+
+        XCTAssertEqual(feed.lastPage, expectedPage(200))
+    }
+
+    func testPreviousPageIsEqualToLinksCurrentPageMinusOne() {
+        let feed = testFeed(
+            links: Feed.Links(
+                alternate: fakeLink,
+                current: exampleLink(123),
+                first: exampleLink(1),
+                last: exampleLink(200),
+                previous: exampleLink(122),
+                next: exampleLink(124)))
+
+        XCTAssertEqual(feed.previousPage, expectedPage(122))
+    }
+
+    func testPreviousPageIsNilWhenCurrentPageIsTheFirst() {
+        let feed = testFeed(
+            links: Feed.Links(
+                alternate: fakeLink,
+                current: exampleLink(1),
+                first: exampleLink(1),
+                last: exampleLink(200),
+                previous: exampleLink(122),
+                next: exampleLink(124)))
+
+        XCTAssertNil(feed.previousPage)
+    }
+
+    func testNextPageIsEqualToLinksNextPagePlusOne() {
+        let feed = testFeed(
+            links: Feed.Links(
+                alternate: fakeLink,
+                current: exampleLink(123),
+                first: exampleLink(1),
+                last: exampleLink(200),
+                previous: exampleLink(122),
+                next: exampleLink(124)))
+
+        XCTAssertEqual(feed.nextPage, expectedPage(124))
+    }
+
+    func testNextPageIsNilWhenCurrentPageIsTheLast() {
+        let feed = testFeed(
+            links: Feed.Links(
+                alternate: fakeLink,
+                current: exampleLink(200),
+                first: exampleLink(1),
+                last: exampleLink(200),
+                previous: exampleLink(122),
+                next: exampleLink(124)))
+
+        XCTAssertNil(feed.nextPage)
     }
 
     static var allTests = [
-        ("testTODO", testTODO),
+        ("testCurrentPageIsEqualToLinksCurrentPage", testCurrentPageIsEqualToLinksCurrentPage),
+        ("testFirstPageIsEqualToLinksFirstPage", testFirstPageIsEqualToLinksFirstPage),
+        ("testLastPageIsEqualToLinksLastPage", testLastPageIsEqualToLinksLastPage),
+        ("testPreviousPageIsEqualToLinksCurrentPageMinusOne", testPreviousPageIsEqualToLinksCurrentPageMinusOne),
+        ("testPreviousPageIsNilWhenCurrentPageIsTheFirst", testPreviousPageIsNilWhenCurrentPageIsTheFirst),
+        ("testNextPageIsEqualToLinksNextPagePlusOne", testNextPageIsEqualToLinksNextPagePlusOne),
+        ("testNextPageIsNilWhenCurrentPageIsTheLast", testNextPageIsNilWhenCurrentPageIsTheLast),
     ]
 }
+
+// MARK: - Helpers
+
+private extension FeedExtensionsTests {
+    func testFeed(links: Feed.Links) -> Feed {
+        Feed(
+            author: Feed.Author(name: "", uri: fakeLink),
+            entries: [],
+            title: "",
+            rights: "",
+            updated: Date(),
+            links: links)
+    }
+
+    var fakeLink: URL {
+        URL(string: "https://56north.co")!
+    }
+
+    func exampleLink(_ pageNumber: Int) -> URL {
+        URL(string: "https://itunes.apple.com/gb/rss/customerreviews/page=\(pageNumber)/id=1510826067/sortby=mostrecent/xml?l=en&urlDesc=/customerreviews/page=\(pageNumber)/id=1510826067/sortby=mostrecent/json")!
+    }
+
+    func expectedPage(_ pageNumber: Int) -> Page {
+        try! Page(appID: 1510826067, territory: .GB, page: pageNumber)
+    }
+}