Add unit tests

Tests/DataLiteCoreTests/Structures/PragmaTests.swift

@@ -0,0 +1,30 @@
+import Testing
+
+@testable import DataLiteCore
+
+struct PragmaTests {
+    @Test(arguments: [
+        (Pragma.applicationID, "application_id"),
+        (Pragma.foreignKeys, "foreign_keys"),
+        (Pragma.journalMode, "journal_mode"),
+        (Pragma.synchronous, "synchronous"),
+        (Pragma.userVersion, "user_version"),
+        (Pragma.busyTimeout, "busy_timeout")
+    ])
+    func predefinedPragmas(_ pragma: Pragma, _ expected: String) {
+        #expect(pragma.rawValue == expected)
+        #expect(pragma.description == expected)
+    }
+    
+    @Test func initRawValue() {
+        let pragma = Pragma(rawValue: "custom_pragma")
+        #expect(pragma.rawValue == "custom_pragma")
+        #expect(pragma.description == "custom_pragma")
+    }
+    
+    @Test func initStringLiteral() {
+        let pragma: Pragma = "another_pragma"
+        #expect(pragma.rawValue == "another_pragma")
+        #expect(pragma.description == "another_pragma")
+    }
+}