Expanded variable RVR regex to be more strict and account for north american style METAR (fixes #115) (#116)

Author: fkrauthan

src/command/metar/RunwayCommand.ts

@@ -12,7 +12,8 @@ import { ICommand } from "../metar";
 
 export class RunwayCommand implements ICommand {
   #genericRegex = /^(R\d{2}\w?\/)/;
-  #runwayMaxRangeRegex = /^R(\d{2}\w?)\/(\d{4})V(\d{3,4})([UDN])?(FT)?/;
+  #runwayMaxRangeRegex =
+    /^R(\d{2}\w?)\/(\d{4})V(\d{3,4})(?:([UDN])|(FT)(?:\/([UDN]))?)$/;
   #runwayRegex = /^R(\d{2}\w?)\/([MP])?(\d{4})(?:([UDN])|(FT)(?:\/([UDN]))?)$/;
   #runwayDepositRegex = /^R(\d{2}\w?)\/([/\d])([/\d])(\/\/|\d{2})(\/\/|\d{2})$/;
 
@@ -63,7 +64,10 @@ export class RunwayCommand implements ICommand {
 
       if (!matches) throw new UnexpectedParseError("Should be able to parse");
 
-      const trend = matches[4] ? as(matches[4], RunwayInfoTrend) : undefined;
+      const trend = (() => {
+        if (matches[6]) return as(matches[6], RunwayInfoTrend);
+        if (matches[4]) return as(matches[4], RunwayInfoTrend);
+      })();
       const unit = matches[5]
         ? as(matches[5], RunwayInfoUnit)
         : RunwayInfoUnit.Meters;

tests/command/metar/RunwayCommand.test.ts

@@ -98,6 +98,30 @@ describe("RunwayCommand", () => {
     });
   })();
 
+  (() => {
+    const code = "R08L/1400V1800FT/N"; // runway info range north america style
+    const metar = { runwaysInfo: [] } as unknown as IMetar;
+
+    describe(code, () => {
+      test("canParse", () => {
+        expect(command.canParse(code)).toBe(true);
+      });
+
+      test("parse", () => {
+        command.execute(metar, code);
+
+        expect(metar.runwaysInfo).toHaveLength(1);
+        expect(metar.runwaysInfo[0]).toEqual({
+          name: "08L",
+          minRange: 1400,
+          maxRange: 1800,
+          unit: RunwayInfoUnit.Feet,
+          trend: RunwayInfoTrend.NoSignificantChange,
+        });
+      });
+    });
+  })();
+
   (() => {
     const code = "R01L/0800FT"; // runway info range feet simple
     const metar = { runwaysInfo: [] } as unknown as IMetar;