Rework parsing structure

tests/parser/ScriptParserTests.kt

@@ -0,0 +1,36 @@
+package parser
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertInstanceOf
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import prolog.ast.logic.Fact
+import prolog.ast.terms.Atom
+import prolog.logic.equivalent
+import kotlin.test.assertTrue
+
+class ScriptParserTests {
+    private lateinit var parser: ScriptParser
+
+    @BeforeEach
+    fun setup() {
+        parser = ScriptParser()
+    }
+
+    @Test
+    fun `parse single atom`() {
+        val input = """
+            a.
+        """.trimIndent()
+
+        val result = parser.parse(input)
+        val expected = Fact(Atom("a"))
+
+        assertEquals(1, result.size, "Should return one result")
+        assertInstanceOf(Fact::class.java, result[0], "Result should be a fact")
+        assertTrue(
+            equivalent(expected.head, result[0].head, emptyMap()),
+            "Expected fact 'a'"
+        )
+    }
+}