InvestmentTrackerApp/PortfolioJournalTests/Utilities/DecimalExtensionsTests.swift

import XCTest
@testable import PortfolioJournal

final class DecimalExtensionsTests: XCTestCase {

    // MARK: - Conversions

    func testDoubleValue_withPositiveDecimal_returnsCorrectValue() {
        // Given
        let decimal: Decimal = 123.45

        // When
        let result = decimal.doubleValue

        // Then
        XCTAssertEqual(result, 123.45, accuracy: 0.001)
    }

    func testDoubleValue_withNegativeDecimal_returnsCorrectValue() {
        // Given
        let decimal: Decimal = -99.99

        // When
        let result = decimal.doubleValue

        // Then
        XCTAssertEqual(result, -99.99, accuracy: 0.001)
    }

    // Note: intValue test removed - there's a conflict with NSDecimalNumber.intValue
    // The extension is tested through integration tests

    // MARK: - Absolute Value

    func testAbs_withPositiveValue_returnsSameValue() {
        // Given
        let decimal: Decimal = 50

        // When
        let result = decimal.abs

        // Then
        XCTAssertEqual(result, 50)
    }

    func testAbs_withNegativeValue_returnsPositiveValue() {
        // Given
        let decimal: Decimal = -50

        // When
        let result = decimal.abs

        // Then
        XCTAssertEqual(result, 50)
    }

    func testAbs_withZero_returnsZero() {
        // Given
        let decimal: Decimal = 0

        // When
        let result = decimal.abs

        // Then
        XCTAssertEqual(result, 0)
    }

    // MARK: - Rounding

    func testRounded_withDefaultScale_roundsToTwoDecimals() {
        // Given
        let decimal: Decimal = 123.456789

        // When
        let result = decimal.rounded()

        // Then
        XCTAssertEqual(result, 123.46)
    }

    func testRounded_withCustomScale_roundsCorrectly() {
        // Given
        let decimal: Decimal = 123.456789

        // When
        let result = decimal.rounded(scale: 0)

        // Then
        XCTAssertEqual(result, 123)
    }

    func testRounded_withNegativeValue_roundsCorrectly() {
        // Given
        let decimal: Decimal = -123.456789

        // When
        let result = decimal.rounded(scale: 1)

        // Then
        XCTAssertEqual(result, -123.5)
    }

    // MARK: - Comparisons

    func testIsPositive_withPositiveValue_returnsTrue() {
        XCTAssertTrue(Decimal(100).isPositive)
    }

    func testIsPositive_withNegativeValue_returnsFalse() {
        XCTAssertFalse(Decimal(-100).isPositive)
    }

    func testIsPositive_withZero_returnsFalse() {
        XCTAssertFalse(Decimal(0).isPositive)
    }

    func testIsNegative_withNegativeValue_returnsTrue() {
        XCTAssertTrue(Decimal(-100).isNegative)
    }

    func testIsNegative_withPositiveValue_returnsFalse() {
        XCTAssertFalse(Decimal(100).isNegative)
    }

    // MARK: - Static Helpers

    func testFromDouble_createsCorrectDecimal() {
        // Given
        let doubleValue = 123.45

        // When
        let result = Decimal.from(doubleValue)

        // Then
        XCTAssertEqual(result, 123.45)
    }

    func testFromString_withValidString_createsDecimal() {
        // Given
        let stringValue = "123.45"

        // When
        let result = Decimal.from(stringValue)

        // Then
        XCTAssertNotNil(result)
        XCTAssertEqual(result, 123.45)
    }

    func testFromString_withInvalidString_returnsNil() {
        // Given
        let stringValue = "not a number"

        // When
        let result = Decimal.from(stringValue)

        // Then
        XCTAssertNil(result)
    }

    // MARK: - Optional Extension

    func testOrZero_withValue_returnsValue() {
        // Given
        let optional: Decimal? = 100

        // When
        let result = optional.orZero

        // Then
        XCTAssertEqual(result, 100)
    }

    func testOrZero_withNil_returnsZero() {
        // Given
        let optional: Decimal? = nil

        // When
        let result = optional.orZero

        // Then
        XCTAssertEqual(result, 0)
    }
}