apt/fuelboard
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Best Value: candidate-priced fills, key copy, detail total

Browse Source
This commit is contained in:
FuelBoard Contributor
2026-10-14 10:43:12 +01:00
parent 2ed9cbf4e8
commit 3c424ab397
9 changed files with 218 additions and 80 deletions
Download Patch File Download Diff File Expand all files Collapse all files
FuelBoardTests/Tests/FuelBoardSharedTests/FuelSavingsCalculationAuditTests.swift
+97 -31
View File
@@ -82,18 +82,84 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
XCTAssertEqual(FuelSavingsFormat.distance(1, unit: .miles), DistanceUnit.miles.format(1.609344))
}
// MARK: - 2/4. The three stations from the brief
// MARK: - 2. Candidate-priced fill-up
func testPoundsFillUsesCandidatePriceForLitresAndGrossSaving() throws {
let result = try FuelSavingsCalculator.calculate(
mpg: 30,
amount: FuelSavingsFillAmount(value: 60, unit: .pounds),
baselinePricePencePerLitre: 171.9,
candidatePricePencePerLitre: 169.9,
baselineJourneyMiles: 0.879,
candidateJourneyMiles: 8.306
)
XCTAssertEqual(result.fillLitres, 60 / 1.699, accuracy: 1e-9)
XCTAssertEqual(result.grossSavingGBP, (60 / 1.699) * 0.02, accuracy: 1e-9)
XCTAssertEqual(FuelSavingsFormat.money(result.grossSavingGBP), "£0.71")
XCTAssertEqual(result.extraFuelLitres, 1.1254603476666667, accuracy: 1e-9)
XCTAssertEqual(result.extraDrivingCostGBP, 1.9121571306856667, accuracy: 1e-9)
XCTAssertEqual(result.netSavingGBP, -1.2058593084372853, accuracy: 1e-9)
XCTAssertEqual(result.headline(), "Costs £1.21 more")
}
func testPoundsExamplesScaleFromThirtyToOneHundredPounds() throws {
for (budget, expectedLitres, expectedGross) in [
(30.0, 17.657445556209535, 0.3531489111241907),
(60.0, 35.31489111241907, 0.7062978222483814),
(100.0, 58.85815185403179, 1.1771630370806357)
] {
let result = try FuelSavingsCalculator.calculate(
mpg: 30,
amount: FuelSavingsFillAmount(value: budget, unit: .pounds),
baselinePricePencePerLitre: 171.9,
candidatePricePencePerLitre: 169.9,
baselineJourneyMiles: 0,
candidateJourneyMiles: 0
)
XCTAssertEqual(result.fillLitres, expectedLitres, accuracy: 1e-8)
XCTAssertEqual(result.grossSavingGBP, expectedGross, accuracy: 1e-8)
}
}
func testCandidatePriceControlsLitresWhileBaselinePriceOnlyChangesSaving() throws {
let amount = FuelSavingsFillAmount(value: 60, unit: .pounds)
let first = try FuelSavingsCalculator.calculate(
mpg: 30, amount: amount,
baselinePricePencePerLitre: 171.9,
candidatePricePencePerLitre: 169.9,
baselineJourneyMiles: 0, candidateJourneyMiles: 0
)
let differentBaseline = try FuelSavingsCalculator.calculate(
mpg: 30, amount: amount,
baselinePricePencePerLitre: 179.9,
candidatePricePencePerLitre: 169.9,
baselineJourneyMiles: 0, candidateJourneyMiles: 0
)
let differentCandidate = try FuelSavingsCalculator.calculate(
mpg: 30, amount: amount,
baselinePricePencePerLitre: 179.9,
candidatePricePencePerLitre: 159.9,
baselineJourneyMiles: 0, candidateJourneyMiles: 0
)
XCTAssertEqual(first.fillLitres, differentBaseline.fillLitres, accuracy: 1e-12)
XCTAssertNotEqual(first.grossSavingGBP, differentBaseline.grossSavingGBP)
XCTAssertNotEqual(differentBaseline.fillLitres, differentCandidate.fillLitres)
}
// MARK: - 3/5. The three stations from the brief
func testBriefCaseTescoBradfordIsMarginallyWorseOff() throws {
let result = try briefResult(candidatePrice: 170.9, extraMiles: 2.0)
XCTAssertEqual(result.fillLitres, 34.904014, accuracy: 1e-6)
XCTAssertEqual(result.grossSavingGBP, 0.349040, accuracy: 1e-6, "1p/litre cheaper on a 34.90 L fill")
XCTAssertEqual(result.fillLitres, 35.108250, accuracy: 1e-6)
XCTAssertEqual(result.grossSavingGBP, 0.351083, accuracy: 1e-6, "£60 buys 35.11 L at the candidate price")
XCTAssertEqual(result.extraDistanceMiles, 2.0, accuracy: 1e-9)
XCTAssertEqual(result.extraDrivingCostGBP, 0.517951, accuracy: 1e-6)
XCTAssertEqual(result.netSavingGBP, -0.168911, accuracy: 1e-6)
XCTAssertEqual(result.netSavingGBP, -0.166869, accuracy: 1e-6)
XCTAssertEqual(result.status, .notWorthTheDrive)
XCTAssertEqual(result.headline(), "£0.17 worse off after travel")
XCTAssertEqual(result.headline(), "Costs £0.17 more")
}
/// The brief recorded "£0.18 worse off" for this row against a displayed
@@ -104,9 +170,9 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
/// is entirely the rounding of the distance, not of the money.
func testTheReportedEighteenPenceIsRoundedExtraDistanceNotARoundingBug() throws {
XCTAssertEqual(try briefResult(candidatePrice: 170.9, extraMiles: 2.00).headline(),
"£0.17 worse off after travel")
"Costs £0.17 more")
XCTAssertEqual(try briefResult(candidatePrice: 170.9, extraMiles: 2.05).headline(),
"£0.18 worse off after travel")
"Costs £0.18 more")
// 2.05 mi shows as "2.0 mi" at one decimal place — the same caption.
XCTAssertEqual(FuelSavingsFormat.extraTravelLabel(extraDistanceMiles: 2.05, unit: .miles),
@@ -118,13 +184,13 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
func testBriefCaseMFGHareAndHoundsIsWorseOff() throws {
let result = try briefResult(candidatePrice: 172.9, extraMiles: 2.8)
XCTAssertEqual(result.fillLitres, 34.904014, accuracy: 1e-6)
XCTAssertEqual(result.grossSavingGBP, -0.349040, accuracy: 1e-6, "1p/litre dearer costs 34.90 L × 1p")
XCTAssertEqual(result.fillLitres, 34.702140, accuracy: 1e-6)
XCTAssertEqual(result.grossSavingGBP, -0.347021, accuracy: 1e-6, "£60 buys 34.70 L at the candidate price")
XCTAssertEqual(result.extraDistanceMiles, 2.8, accuracy: 1e-9)
XCTAssertEqual(result.extraDrivingCostGBP, 0.733618, accuracy: 1e-6)
XCTAssertEqual(result.netSavingGBP, -1.082658, accuracy: 1e-6)
XCTAssertEqual(result.netSavingGBP, -1.080639, accuracy: 1e-6)
XCTAssertEqual(result.status, .notWorthTheDrive)
XCTAssertEqual(result.headline(), "£1.08 worse off after travel")
XCTAssertEqual(result.headline(), "Costs £1.08 more")
}
func testBriefCasePGGNapoleonSamePumpPriceIsTravelCostOnly() throws {
@@ -135,7 +201,7 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
XCTAssertEqual(result.netSavingGBP, -0.729375, accuracy: 1e-6,
"with no price difference the whole result is the extra driving")
XCTAssertEqual(result.status, .notWorthTheDrive)
XCTAssertEqual(result.headline(), "£0.73 worse off after travel")
XCTAssertEqual(result.headline(), "Costs £0.73 more")
}
// MARK: - 5/6. Classification, tolerance and rounding
@@ -150,15 +216,15 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
}
func testSmallSavingInsideTheToleranceIsBreakEvenNotPennies() throws {
// 171.9p vs 170.9p over a 1.23 mi delta: net +£0.0305.
// 171.9p vs 170.9p over a 1.23 mi delta: the small saving remains within tolerance.
let result = try briefResult(candidatePrice: 170.9, extraMiles: 1.23)
XCTAssertEqual(result.netSavingGBP, 0.030500, accuracy: 1e-6)
XCTAssertEqual(result.netSavingGBP, 0.03254252417853143, accuracy: 1e-9)
XCTAssertEqual(result.status, .breakEven, "±5p reads as break even rather than a meaningless £0.03")
XCTAssertEqual(result.headline(), "Break even")
}
func testBreakEvenToleranceDecidesTheClassificationAtTheBoundary() throws {
let net = -0.168911
let net = -0.166869
// A tolerance wider than the loss → break even; narrower → worse off.
let lenient = try FuelSavingsCalculator.calculate(
mpg: 30,
@@ -187,7 +253,7 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
func testMoneyIsRoundedOnlyForDisplay() throws {
// Full precision retained internally…
let result = try briefResult(candidatePrice: 172.9, extraMiles: 2.8)
XCTAssertEqual(result.netSavingGBP, -1.082658, accuracy: 1e-6)
XCTAssertEqual(result.netSavingGBP, -1.080639, accuracy: 1e-6)
XCTAssertNotEqual(result.netSavingGBP, -1.08, "the stored value must not be pre-rounded")
// …and rounded to two places only when shown.
XCTAssertEqual(FuelSavingsFormat.money(1.082658), "£1.08")
@@ -237,12 +303,12 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
baselineJourneyMiles: 2.0,
candidateJourneyMiles: 7.0
)
XCTAssertEqual(result.fillLitres, 27.416038, accuracy: 1e-6)
XCTAssertEqual(result.grossSavingGBP, 1.919123, accuracy: 1e-6)
XCTAssertEqual(result.fillLitres, 28.797696, accuracy: 1e-6)
XCTAssertEqual(result.grossSavingGBP, 2.015839, accuracy: 1e-6)
XCTAssertEqual(result.extraDrivingCostGBP, 0.701613, accuracy: 1e-6)
XCTAssertEqual(result.netSavingGBP, 1.217509, accuracy: 1e-6)
XCTAssertEqual(result.netSavingGBP, 1.314226, accuracy: 1e-6)
XCTAssertEqual(result.status, .worthTheDrive)
XCTAssertEqual(result.headline(), "£1.22 better off after travel")
XCTAssertEqual(result.headline(), "Save £1.31")
}
func testNearerCandidateIsNeverChargedExtraTravel() throws {
@@ -270,9 +336,9 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
baselineJourneyMiles: 0.8,
candidateJourneyMiles: 3.6
)
XCTAssertEqual(sixty.grossSavingGBP, -0.349040, accuracy: 1e-6, "MPG must not touch the pump saving")
XCTAssertEqual(sixty.grossSavingGBP, -0.347021, accuracy: 1e-6, "MPG must not touch the pump saving")
XCTAssertEqual(sixty.extraDrivingCostGBP, 0.366809, accuracy: 1e-6)
XCTAssertEqual(sixty.netSavingGBP, -0.715849, accuracy: 1e-6)
XCTAssertEqual(sixty.netSavingGBP, -0.713830, accuracy: 1e-6)
let fortyFive = try FuelSavingsCalculator.calculate(
mpg: 45,
@@ -283,7 +349,7 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
candidateJourneyMiles: 3.6
)
XCTAssertEqual(fortyFive.extraDrivingCostGBP, 0.489078, accuracy: 1e-6)
XCTAssertEqual(fortyFive.netSavingGBP, -0.838119, accuracy: 1e-6)
XCTAssertEqual(fortyFive.netSavingGBP, -0.836100, accuracy: 1e-6)
}
func testDifferentFillBudgetsScaleOnlyThePumpSaving() throws {
@@ -295,10 +361,10 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
baselineJourneyMiles: 0.8,
candidateJourneyMiles: 3.6
)
XCTAssertEqual(forty.fillLitres, 23.269343, accuracy: 1e-6, "£40 buys 23.27 L at 171.9p")
XCTAssertEqual(forty.grossSavingGBP, -0.232693, accuracy: 1e-6)
XCTAssertEqual(forty.fillLitres, 23.134760, accuracy: 1e-6, "£40 buys 23.13 L at the candidate price")
XCTAssertEqual(forty.grossSavingGBP, -0.231348, accuracy: 1e-6)
XCTAssertEqual(forty.extraDrivingCostGBP, 0.733618, accuracy: 1e-6, "the journey cost is budget-independent")
XCTAssertEqual(forty.netSavingGBP, -0.966311, accuracy: 1e-6)
XCTAssertEqual(forty.netSavingGBP, -0.964965, accuracy: 1e-6)
let ninety = try FuelSavingsCalculator.calculate(
mpg: 30,
@@ -308,9 +374,9 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
baselineJourneyMiles: 0.8,
candidateJourneyMiles: 3.6
)
XCTAssertEqual(ninety.fillLitres, 52.356021, accuracy: 1e-6)
XCTAssertEqual(ninety.grossSavingGBP, -0.523560, accuracy: 1e-6)
XCTAssertEqual(ninety.netSavingGBP, -1.257178, accuracy: 1e-6)
XCTAssertEqual(ninety.fillLitres, 52.053210, accuracy: 1e-6)
XCTAssertEqual(ninety.grossSavingGBP, -0.520532, accuracy: 1e-6)
XCTAssertEqual(ninety.netSavingGBP, -1.254150, accuracy: 1e-6)
}
func testFillUpInLitresIsFixedRegardlessOfPrice() throws {
@@ -370,7 +436,7 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
journey: journey(2.8),
baselineJourney: journey(0.8)
)
XCTAssertEqual(both?.result?.netSavingGBP ?? 0, -0.168911, accuracy: 1e-6)
XCTAssertEqual(both?.result?.netSavingGBP ?? 0, -0.166869, accuracy: 1e-6)
}
func testMixedRouteBasisIsReportedAsAnEstimate() {
@@ -393,7 +459,7 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
XCTAssertEqual(mixed?.result?.distanceBasis, .straightLine,
"one unmeasured leg makes the whole estimate an estimate")
XCTAssertEqual(mixed?.result?.journeyConfidence, .estimated)
XCTAssertEqual(mixed?.result?.headline(compact: true), "Approx. £0.17 worse off after travel")
XCTAssertEqual(mixed?.result?.headline(compact: true), "Approx. Costs £0.17 more")
}
func testBaselineStationIsLabelledClosestStationNotBreakEven() {