Add roundtrip test for source location conversions.

Author: toinehartman

rascal-lsp/src/test/java/engineering/swat/rascal/lsp/util/LocationsTest.java

@@ -0,0 +1,30 @@
+package engineering.swat.rascal.lsp.util;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+import org.rascalmpl.values.IRascalValueFactory;
+import org.rascalmpl.vscode.lsp.util.locations.ColumnMaps;
+import org.rascalmpl.vscode.lsp.util.locations.Locations;
+
+public class LocationsTest {
+
+    @Test
+    public void roundtrip() {
+        var VF = IRascalValueFactory.getInstance();
+        var fileName = "PNG.bird";
+        var contents = "module images::PNG\r\n" + //
+                        "\r\n" + //
+                        "struct Signature {\r\n" + //
+                        "    u8 _ ?(== 0x89)\r\n" + //
+                        "    byte[] _[3] ?(== \"PNG\")\r\n" + //
+                        "    byte[] _[4] ?(== <0x0d, 0x0a, 0x1a, 0x0a>)\r\n" + //
+                        "}\r\n" + //
+                        "";
+        var columns = new ColumnMaps(f -> contents);
+        var in = VF.sourceLocation(fileName, 22, 119, 3, 7, 0, 1); // the structure
+        var range = Locations.toRange(in, columns);
+        var out = Locations.setRange(in, range, columns);
+        assertEquals(in, out);
+    }
+}