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Fix failing duplicate identifier detection #375

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Fix failing duplicate identifier detection #375

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b2efc81
Add tests that show failing duplicate identifier detection
teameh Oct 8, 2020
c1f8a49
Fix failing duplicate identity detection
teameh Oct 8, 2020
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Expand Up @@ -6,6 +6,7 @@ All notable changes to this project will be documented in this file.
#### Master

* Added support of mutable CellViewModels.
* Fixes failing duplicate identity detection

## [4.0.1](https://github.com/RxSwiftCommunity/RxDataSources/releases/tag/4.0.1)

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16 changes: 16 additions & 0 deletions Sources/Differentiator/Diff.swift
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Expand Up @@ -199,11 +199,19 @@ public enum Diff {
dictionary[key] = i
}

var finalKeys = Set<OptimizedIdentity<Identity>>()

for (i, items) in finalItemCache.enumerated() {
for j in 0 ..< items.count {
let item = items[j]
var identity = item.identity
let key = OptimizedIdentity(&identity)

if finalKeys.contains(key) {
throw Error.duplicateItem(item: item)
}
finalKeys.insert(key)

guard let initialItemPathIndex = dictionary[key] else {
continue
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@teameh teameh Oct 8, 2020 •
edited
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The problem here is that if the item was not present in the initial sections, we always continue and it's never checked if the finalSections contain items with duplicate identifiers!

}
Expand Down Expand Up @@ -518,8 +526,16 @@ public enum Diff {
var initialSectionData = ContiguousArray<SectionAssociatedData>(repeating: SectionAssociatedData.initial, count: initialSections.count)
var finalSectionData = ContiguousArray<SectionAssociatedData>(repeating: SectionAssociatedData.initial, count: finalSections.count)

var finalSectionIdentities = Set<Section.Identity>()

for (i, section) in finalSections.enumerated() {
finalSectionData[i].itemCount = finalSections[i].items.count

if finalSectionIdentities.contains(section.identity) {
throw Error.duplicateSection(section: section)
}
finalSectionIdentities.insert(section.identity)

guard let initialSectionIndex = initialSectionIndexes[section.identity] else {
continue
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Same here, we need to not only look in the initialSectionIndexes but also store the identity in an extra Set (any better data types for this use case?) and check if the final sections don't contain any duplicates

}
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106 changes: 100 additions & 6 deletions Tests/RxDataSourcesTests/AlgorithmTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -320,8 +320,77 @@ extension AlgorithmTests {

// errors
extension AlgorithmTests {
func testThrowsErrorOnDuplicateItem() {
let initial: [s] = [
func testThrowsErrorOnDuplicateItem_inInitialSections() {
let sections: [s] = [
s(1, [
i(1111, ""),
i(1111, "")
])
]

do {
_ = try Diff.differencesForSectionedView(initialSections: sections, finalSections: sections)
XCTFail("Should throw exception")
}
catch let exception {
guard case let .duplicateItem(item) = exception as! Diff.Error else {
XCTFail("Not required error")
return
}

XCTAssertEqual(item as! i, i(1111, ""))
}
}

func testThrowsErrorOnDuplicateItem_inFinalSections() {
let final: [s] = [
s(1, [
i(1111, ""),
i(1111, "")
])
]

do {
_ = try Diff.differencesForSectionedView(initialSections: [], finalSections: final)
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Without the fix this will not throw

XCTFail("Should throw exception")
}
catch let exception {
guard case let .duplicateItem(item) = exception as! Diff.Error else {
XCTFail("Not required error")
return
}

XCTAssertEqual(item as! i, i(1111, ""))
}
}

func testThrowsErrorOnDuplicateItemInDifferentSection_inInitialSections() {
let sections: [s] = [
s(1, [
i(1111, "")
]),
s(2, [
i(1111, "")
])

]

do {
_ = try Diff.differencesForSectionedView(initialSections: sections, finalSections: sections)
XCTFail("Should throw exception")
}
catch let exception {
guard case let .duplicateItem(item) = exception as! Diff.Error else {
XCTFail("Not required error")
return
}

XCTAssertEqual(item as! i, i(1111, ""))
}
}

func testThrowsErrorOnDuplicateItemInDifferentSection_inFinalSections() {
let final: [s] = [
s(1, [
i(1111, "")
]),
Expand All @@ -332,7 +401,7 @@ extension AlgorithmTests {
]

do {
_ = try Diff.differencesForSectionedView(initialSections: initial, finalSections: initial)
_ = try Diff.differencesForSectionedView(initialSections: [], finalSections: final)
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Without the fix this will not throw

XCTFail("Should throw exception")
}
catch let exception {
Expand All @@ -345,8 +414,33 @@ extension AlgorithmTests {
}
}

func testThrowsErrorOnDuplicateSection() {
let initial: [s] = [
func testThrowsErrorOnDuplicateSection_inInitialSections() {
let sections: [s] = [
s(1, [
i(1111, "")
]),
s(1, [
i(1112, "")
])
]

do {
_ = try Diff.differencesForSectionedView(initialSections: sections, finalSections: sections)
XCTFail("Should throw exception")
}
catch let exception {
guard case let .duplicateSection(section) = exception as! Diff.Error else {
XCTFail("Not required error")
return
}

XCTAssertEqual(section as! s, s(1, [
i(1112, "")
]))
}
}
func testThrowsErrorOnDuplicateSection_inFinalSections() {
let final: [s] = [
s(1, [
i(1111, "")
]),
Expand All @@ -357,7 +451,7 @@ extension AlgorithmTests {
]

do {
_ = try Diff.differencesForSectionedView(initialSections: initial, finalSections: initial)
_ = try Diff.differencesForSectionedView(initialSections: [], finalSections: final)
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Without the fix this will not throw

XCTFail("Should throw exception")
}
catch let exception {
Expand Down