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[#130] Support for Optional Values (#143)
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* Previously, feature-flag stores returned `nil` when the value was not found
* This behavior made it impossible to distinguish between the absence of a value and a literal `nil` value
* While this distinction wasn’t important in the majority of cases, it could be sometimes
* For that reason, optional values were not supported in YMFF
* #132 / #139 changed the protocols for feature-flag stores so they throw errors instead of returning `nil` for nonexistent values
* This change made it possible to accept `nil` as a valid feature-flag value
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@yakovmanshin
yakovmanshin committed May 12, 2024
1 parent ec331f7 commit f78a313
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Showing 3 changed files with 202 additions and 55 deletions.
5 changes: 0 additions & 5 deletions Sources/YMFF/FeatureFlagResolver/FeatureFlagResolver+Error.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -23,11 +23,6 @@ extension FeatureFlagResolver {
/// The feature-flag store has thrown an error.
case storeError(any Swift.Error)

/// Currently, optional values are not supported by the `FeatureFlagResolver`.
///
/// - Note: Support for optional values will be added in [#130](https://github.com/yakovmanshin/YMFF/issues/130).
case optionalValuesNotAllowed

}

}
24 changes: 2 additions & 22 deletions Sources/YMFF/FeatureFlagResolver/FeatureFlagResolver.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -54,10 +54,7 @@ final public class FeatureFlagResolver {
extension FeatureFlagResolver: FeatureFlagResolverProtocol {

public func value<Value>(for key: FeatureFlagKey) async throws -> Value {
let retrievedValue: Value = try await retrieveFirstValue(forKey: key)
try validateValue(retrievedValue)

return retrievedValue
try await retrieveFirstValue(forKey: key)
}

public func setValue<Value>(_ newValue: Value, toMutableStoreUsing key: FeatureFlagKey) async throws {
Expand All @@ -66,8 +63,6 @@ extension FeatureFlagResolver: FeatureFlagResolverProtocol {
throw Error.noStoreAvailable
}

try validateValue(newValue)

for store in getStores() {
if
case .failure(let error) = await store.value(forKey: key) as Result<Value, _>,
Expand Down Expand Up @@ -118,10 +113,7 @@ extension FeatureFlagResolver: FeatureFlagResolverProtocol {
extension FeatureFlagResolver: SynchronousFeatureFlagResolverProtocol {

public func valueSync<Value>(for key: FeatureFlagKey) throws -> Value {
let retrievedValue: Value = try retrieveFirstValueSync(forKey: key)
try validateValue(retrievedValue)

return retrievedValue
try retrieveFirstValueSync(forKey: key)
}

public func setValueSync<Value>(_ newValue: Value, toMutableStoreUsing key: FeatureFlagKey) throws {
Expand All @@ -130,8 +122,6 @@ extension FeatureFlagResolver: SynchronousFeatureFlagResolverProtocol {
throw Error.noStoreAvailable
}

try validateValue(newValue)

for store in getSyncStores() {
if
case .failure(let error) = store.valueSync(forKey: key) as Result<Value, _>,
Expand Down Expand Up @@ -253,14 +243,4 @@ extension FeatureFlagResolver {
throw Error.valueNotFoundInStores(key: key)
}

func validateValue<Value>(_ value: Value) throws {
if valueIsOptional(value) {
throw Error.optionalValuesNotAllowed
}
}

func valueIsOptional<Value>(_ value: Value) -> Bool {
value is ExpressibleByNilLiteral
}

}
228 changes: 200 additions & 28 deletions Tests/YMFFTests/Cases/FeatureFlagResolverTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -244,33 +244,73 @@ final class FeatureFlagResolverTests: XCTestCase {
}
}

func test_value_optionalValue() async {
func test_value_optionalValue_nonNil() async {
let store = FeatureFlagStoreMock()
configuration.stores = [store]
store.value_result = .success((123 as Int?)!)
let optionalInt: Int? = 123
store.value_result = .success(optionalInt as Any)

do {
let _: Int? = try await resolver.value(for: "TEST_key1")
XCTFail("Expected an error")
} catch FeatureFlagResolver.Error.optionalValuesNotAllowed {
let value: Int? = try await resolver.value(for: "TEST_key1")

XCTAssertEqual(store.value_invocationCount, 1)
XCTAssertEqual(store.value_keys, ["TEST_key1"])
XCTAssert(type(of: value) == Optional<Int>.self)
XCTAssertEqual(value, 123)
} catch {
XCTFail("Unexpected error: \(error)")
}
}

func test_valueSync_optionalValue() {
func test_valueSync_optionalValue_nonNil() {
let store = SynchronousFeatureFlagStoreMock()
configuration.stores = [store]
store.valueSync_result = .success((123 as Int?)!)
let optionalInt: Int? = 123
store.valueSync_result = .success(optionalInt as Any)

do {
let _: Int? = try resolver.valueSync(for: "TEST_key1")
XCTFail("Expected an error")
} catch FeatureFlagResolver.Error.optionalValuesNotAllowed {
let value: Int? = try resolver.valueSync(for: "TEST_key1")

XCTAssertEqual(store.valueSync_invocationCount, 1)
XCTAssertEqual(store.valueSync_keys, ["TEST_key1"])
XCTAssert(type(of: value) == Optional<Int>.self)
XCTAssertEqual(value, 123)
} catch {
XCTFail("Unexpected error: \(error)")
}
}

func test_value_optionalValue_nil() async {
let store = FeatureFlagStoreMock()
configuration.stores = [store]
let optionalString: String? = nil
store.value_result = .success(optionalString as Any)

do {
let value: String? = try await resolver.value(for: "TEST_key1")

XCTAssertEqual(store.value_invocationCount, 1)
XCTAssertEqual(store.value_keys, ["TEST_key1"])
XCTAssert(type(of: value) == Optional<String>.self)
XCTAssertNil(value)
} catch {
XCTFail("Unexpected error: \(error)")
}
}

func test_valueSync_optionalValue_nil() {
let store = SynchronousFeatureFlagStoreMock()
configuration.stores = [store]
let optionalString: String? = nil
store.valueSync_result = .success(optionalString as Any)

do {
let value: String? = try resolver.valueSync(for: "TEST_key1")

XCTAssertEqual(store.valueSync_invocationCount, 1)
XCTAssertEqual(store.valueSync_keys, ["TEST_key1"])
XCTAssert(type(of: value) == Optional<String>.self)
XCTAssertNil(value)
} catch {
XCTFail("Unexpected error: \(error)")
}
Expand Down Expand Up @@ -438,37 +478,169 @@ final class FeatureFlagResolverTests: XCTestCase {
}
}

func test_setValue_singleMutableStore_existingValue_optionalValue() async {
func test_setValue_singleMutableStore_existingValue_nonNilToNonNil() async {
let store = MutableFeatureFlagStoreMock()
configuration.stores = [store]
store.value_result = .success("TEST_value1")
let optionalInt: Int? = 123
store.value_result = .success(optionalInt as Any)

do {
try await resolver.setValue(456 as Int?, toMutableStoreUsing: "TEST_key1")
XCTFail("Expected an error")
} catch FeatureFlagResolver.Error.optionalValuesNotAllowed {
XCTAssertEqual(store.value_invocationCount, 0)
XCTAssertTrue(store.value_keys.isEmpty)
XCTAssertEqual(store.setValue_invocationCount, 0)
XCTAssertTrue(store.setValue_keyValuePairs.isEmpty)
let newValue: Int? = 456
try await resolver.setValue(newValue, toMutableStoreUsing: "TEST_key1")

XCTAssertEqual(store.value_invocationCount, 1)
XCTAssertEqual(store.value_keys, ["TEST_key1"])
XCTAssertEqual(store.setValue_invocationCount, 1)
XCTAssertEqual(store.setValue_keyValuePairs.count, 1)
XCTAssertEqual(store.setValue_keyValuePairs[0].0, "TEST_key1")
XCTAssertEqual(store.setValue_keyValuePairs[0].1 as! Int?, 456)
} catch {
XCTFail("Unexpected error: \(error)")
}
}

func test_setValueSync_singleSyncMutableStore_existingValue_optionalValue() {
func test_setValueSync_singleSyncMutableStore_existingValue_nonNilToNonNil() {
let store = SynchronousMutableFeatureFlagStoreMock()
configuration.stores = [store]
store.valueSync_result = .success("TEST_value1")
let optionalInt: Int? = 123
store.valueSync_result = .success(optionalInt as Any)

do {
try resolver.setValueSync(456 as Int?, toMutableStoreUsing: "TEST_key1")
XCTFail("Expected an error")
} catch FeatureFlagResolver.Error.optionalValuesNotAllowed {
XCTAssertEqual(store.valueSync_invocationCount, 0)
XCTAssertTrue(store.valueSync_keys.isEmpty)
XCTAssertEqual(store.setValueSync_invocationCount, 0)
XCTAssertTrue(store.setValueSync_keyValuePairs.isEmpty)
let newValue: Int? = 456
try resolver.setValueSync(newValue, toMutableStoreUsing: "TEST_key1")

XCTAssertEqual(store.valueSync_invocationCount, 1)
XCTAssertEqual(store.valueSync_keys, ["TEST_key1"])
XCTAssertEqual(store.setValueSync_invocationCount, 1)
XCTAssertEqual(store.setValueSync_keyValuePairs.count, 1)
XCTAssertEqual(store.setValueSync_keyValuePairs[0].0, "TEST_key1")
XCTAssertEqual(store.setValueSync_keyValuePairs[0].1 as! Int?, 456)
} catch {
XCTFail("Unexpected error: \(error)")
}
}

func test_setValue_singleMutableStore_existingValue_nilToNonNil() async {
let store = MutableFeatureFlagStoreMock()
configuration.stores = [store]
let optionalInt: Int? = 123
store.value_result = .success(optionalInt as Any)

do {
let newValue: Int? = nil
try await resolver.setValue(newValue, toMutableStoreUsing: "TEST_key1")

XCTAssertEqual(store.value_invocationCount, 1)
XCTAssertEqual(store.value_keys, ["TEST_key1"])
XCTAssertEqual(store.setValue_invocationCount, 1)
XCTAssertEqual(store.setValue_keyValuePairs.count, 1)
XCTAssertEqual(store.setValue_keyValuePairs[0].0, "TEST_key1")
XCTAssertEqual(store.setValue_keyValuePairs[0].1 as! Int?, nil)
} catch {
XCTFail("Unexpected error: \(error)")
}
}

func test_setValueSync_singleSyncMutableStore_existingValue_nilToNonNil() {
let store = SynchronousMutableFeatureFlagStoreMock()
configuration.stores = [store]
let optionalInt: Int? = 123
store.valueSync_result = .success(optionalInt as Any)

do {
let newValue: Int? = nil
try resolver.setValueSync(newValue, toMutableStoreUsing: "TEST_key1")

XCTAssertEqual(store.valueSync_invocationCount, 1)
XCTAssertEqual(store.valueSync_keys, ["TEST_key1"])
XCTAssertEqual(store.setValueSync_invocationCount, 1)
XCTAssertEqual(store.setValueSync_keyValuePairs.count, 1)
XCTAssertEqual(store.setValueSync_keyValuePairs[0].0, "TEST_key1")
XCTAssertEqual(store.setValueSync_keyValuePairs[0].1 as! Int?, nil)
} catch {
XCTFail("Unexpected error: \(error)")
}
}

func test_setValue_singleMutableStore_existingValue_nonNilToNil() async {
let store = MutableFeatureFlagStoreMock()
configuration.stores = [store]
let optionalInt: Int? = nil
store.value_result = .success(optionalInt as Any)

do {
let newValue: Int? = 456
try await resolver.setValue(newValue, toMutableStoreUsing: "TEST_key1")

XCTAssertEqual(store.value_invocationCount, 1)
XCTAssertEqual(store.value_keys, ["TEST_key1"])
XCTAssertEqual(store.setValue_invocationCount, 1)
XCTAssertEqual(store.setValue_keyValuePairs.count, 1)
XCTAssertEqual(store.setValue_keyValuePairs[0].0, "TEST_key1")
XCTAssertEqual(store.setValue_keyValuePairs[0].1 as! Int?, 456)
} catch {
XCTFail("Unexpected error: \(error)")
}
}

func test_setValueSync_singleSyncMutableStore_existingValue_nonNilToNil() {
let store = SynchronousMutableFeatureFlagStoreMock()
configuration.stores = [store]
let optionalInt: Int? = nil
store.valueSync_result = .success(optionalInt as Any)

do {
let newValue: Int? = 456
try resolver.setValueSync(newValue, toMutableStoreUsing: "TEST_key1")

XCTAssertEqual(store.valueSync_invocationCount, 1)
XCTAssertEqual(store.valueSync_keys, ["TEST_key1"])
XCTAssertEqual(store.setValueSync_invocationCount, 1)
XCTAssertEqual(store.setValueSync_keyValuePairs.count, 1)
XCTAssertEqual(store.setValueSync_keyValuePairs[0].0, "TEST_key1")
XCTAssertEqual(store.setValueSync_keyValuePairs[0].1 as! Int?, 456)
} catch {
XCTFail("Unexpected error: \(error)")
}
}

func test_setValue_singleMutableStore_existingValue_nilToNil() async {
let store = MutableFeatureFlagStoreMock()
configuration.stores = [store]
let optionalInt: Int? = nil
store.value_result = .success(optionalInt as Any)

do {
let newValue: Int? = nil
try await resolver.setValue(newValue, toMutableStoreUsing: "TEST_key1")

XCTAssertEqual(store.value_invocationCount, 1)
XCTAssertEqual(store.value_keys, ["TEST_key1"])
XCTAssertEqual(store.setValue_invocationCount, 1)
XCTAssertEqual(store.setValue_keyValuePairs.count, 1)
XCTAssertEqual(store.setValue_keyValuePairs[0].0, "TEST_key1")
XCTAssertEqual(store.setValue_keyValuePairs[0].1 as! Int?, nil)
} catch {
XCTFail("Unexpected error: \(error)")
}
}

func test_setValueSync_singleSyncMutableStore_existingValue_nilToNil() {
let store = SynchronousMutableFeatureFlagStoreMock()
configuration.stores = [store]
let optionalInt: Int? = nil
store.valueSync_result = .success(optionalInt as Any)

do {
let newValue: Int? = nil
try resolver.setValueSync(newValue, toMutableStoreUsing: "TEST_key1")

XCTAssertEqual(store.valueSync_invocationCount, 1)
XCTAssertEqual(store.valueSync_keys, ["TEST_key1"])
XCTAssertEqual(store.setValueSync_invocationCount, 1)
XCTAssertEqual(store.setValueSync_keyValuePairs.count, 1)
XCTAssertEqual(store.setValueSync_keyValuePairs[0].0, "TEST_key1")
XCTAssertEqual(store.setValueSync_keyValuePairs[0].1 as! Int?, nil)
} catch {
XCTFail("Unexpected error: \(error)")
}
Expand Down

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