Unit tests for APK version parsing & fix typo in parser

Tests/darwin-apk-tests/ApkVersionTests.swift

@@ -0,0 +1,47 @@
+/*
+ * darwin-apk © 2025 Gay Pizza Specifications
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import Testing
+@testable import darwin_apk
+
+@Test func testParseDependency() {
+  for valid in [
+    "bash",
+    "libapparmor=4.1.0-r2",
+    "python3~3.12",
+    "so:libc.musl-x86_64.so.1",
+    "!alsa-lib<1.2.14-r0",
+    "!alsa-lib>1.2.14-r0",
+    "!lld20-libs<20.1.2-r0",
+    "!lld20-libs>20.1.2-r0",
+    "!lld20<20.1.2-r0",
+    "!lld20>20.1.2-r0",
+  ] {
+    #expect(throws: Never.self, "Expected valid: \(valid)") {
+      try ApkVersionRequirement(extract: valid[...])
+    }
+  }
+}
+
+@Test func testVersionValidation() {
+  for valid in [
+    "100",
+    "1.0",
+    "0-r1",
+    "10.2.3-r100",
+    "0.0.0_git20210122-r0",
+    "0.20240527.191746-r2",
+    "9100h-r4",
+  ] {
+    #expect(ApkVersionCompare.validate(valid), "Should be valid: \(valid)")
+  }
+  for invalid in [
+    "a",
+    "0r-10",
+    "10.2.3-100",
+  ] {
+    #expect(!ApkVersionCompare.validate(invalid), "Should be invalid: \(invalid)")
+  }
+}