Add boilerplate test files to package

These are essentially the same files that are generated by Xcode when a new Swift Package is created; they shouldn’t have been deleted in the first place. Their presence (or lack thereof) does not affect the functionality of the package.

Author: AngeloStavrow

Tests/LinuxMain.swift

@@ -0,0 +1,7 @@
+import XCTest
+
+import WriteFreelyTests
+
+var tests = [XCTestCaseEntry]()
+tests += WriteFreelyTests.allTests()
+XCTMain(tests)

Tests/WriteFreelyTests/WriteFreelyTests.swift

@@ -0,0 +1,15 @@
+import XCTest
+@testable import WriteFreely
+
+final class WriteFreelyTests: XCTestCase {
+    func testExample() {
+        // This is an example of a functional test case.
+        // Use XCTAssert and related functions to verify your tests produce the correct
+        // results.
+        XCTAssertEqual(true, !false)
+    }
+
+    static var allTests = [
+        ("testExample", testExample),
+    ]
+}

Tests/WriteFreelyTests/XCTestManifests.swift

@@ -0,0 +1,9 @@
+import XCTest
+
+#if !canImport(ObjectiveC)
+public func allTests() -> [XCTestCaseEntry] {
+    return [
+        testCase(WriteFreelyTests.allTests),
+    ]
+}
+#endif