chore: add ChecksumCalculatorProtocol

Sources/BinaryDependencyManager/Utils/ChecksumCalculatorProtocol.swift

@@ -0,0 +1,9 @@
+
+import Foundation
+import Utils
+
+public protocol ChecksumCalculatorProtocol {
+    func calculateChecksum(fileURL: URL) throws -> String
+}
+
+extension SHA256ChecksumCalculator: ChecksumCalculatorProtocol {}

Sources/Utils/SHA256ChecksumCalculator.swift

@@ -0,0 +1,47 @@
+import Crypto
+import Foundation
+
+public struct SHA256ChecksumCalculator {
+    public init() {}
+
+    public func calculateChecksum(fileURL: URL) throws -> String {
+        // Read the file in chunks to avoid RAM usage issues
+
+        let handle: FileHandle = try FileHandle(forReadingFrom: fileURL)
+        var hasher: SHA256 = SHA256()
+
+        #if os(macOS)
+
+        while autoreleasepool(invoking: {
+            let nextChunk = handle.readData(ofLength: 1024 * 1024)
+            guard !nextChunk.isEmpty else { return false }
+            hasher.update(data: nextChunk)
+            return true
+        }) {}
+
+        #elseif os(Linux)
+
+        var eof: Bool = false
+        var nextChunk: Data
+
+        while !eof {
+            nextChunk = handle.readData(ofLength: 1024 * 1024)
+            eof = nextChunk.isEmpty
+            if !eof {
+                hasher.update(data: nextChunk)
+            }
+        }
+
+        #endif
+
+        let digest: SHA256.Digest = hasher.finalize()
+
+        return digest.hexadecimalString
+    }
+}
+
+extension SHA256.Digest {
+    fileprivate var hexadecimalString: String {
+        map { String(format: "%02hhx", $0) }.joined()
+    }
+}

Tests/BinaryDependencyManagerTests/Mocks/ChecksumCalculatorProtocolMock.swift

@@ -0,0 +1,29 @@
+import Foundation
+
+@testable import BinaryDependencyManager
+import Utils
+
+/// Mock implementation for UnarchiverProtocol for use in unit tests.
+class ChecksumCalculatorProtocolMock: ChecksumCalculatorProtocol {
+    /// Records the arguments with which unzip was called.
+    public private(set) var unzipCalls: [(archivePath: String, outputFilePath: String)] = []
+    /// If set, unzip will throw this error when called.
+    public var errorToThrow: Error?
+
+    public init(errorToThrow: Error? = nil) {
+        self.errorToThrow = errorToThrow
+    }
+
+    var checksums: [URL: String] = [:]
+    var checksumCalls: [URL] = []
+    public func calculateChecksum(fileURL: URL) throws -> String {
+        checksumCalls.append(fileURL)
+        if let errorToThrow {
+            throw errorToThrow
+        }
+        guard let checksum = checksums[fileURL] else {
+            throw GenericError("no checksum provided for \(fileURL.relativeFilePath)")
+        }
+        return checksum
+    }
+}