From e91082a56f96da7a2e595c1d4bc0e68bb7831888 Mon Sep 17 00:00:00 2001
From: fuleinist <fuleinist@users.noreply.github.com>
Date: Wed, 12 Aug 2026 05:05:13 +1000
Subject: [PATCH] fix(ResultFormatter): guard
 heading/airspeed/groundspeed/mach/day/month/departureDay/arrivalDay against
 NaN (issue #494)

---
 lib/utils/result_formatter.test.ts | 54 ++++++++++++++++++++++++++++++
 lib/utils/result_formatter.ts      | 24 +++++++++++++
 2 files changed, 78 insertions(+)

diff --git a/lib/utils/result_formatter.test.ts b/lib/utils/result_formatter.test.ts
index 510c5c5..fce4381 100644
--- a/lib/utils/result_formatter.test.ts
+++ b/lib/utils/result_formatter.test.ts
@@ -95,3 +95,57 @@ describe('ResultFormatter timestamp family NaN guards', () => {
     expect(dr.formatted.items[0].value).toBe('02:08:00');
   });
 });
+
+describe('ResultFormatter numeric formatters NaN guards', () => {
+  // Non-numeric ACARS fields ('---', '***', whitespace) become NaN via
+  // Number()/parseInt(); these must disappear from formatted.items rather
+  // than surfacing as literal "NaN" strings (issue #494).
+  const cases: Array<[string, (dr: DecodeResult) => void, string]> = [
+    ['heading', (dr) => ResultFormatter.heading(dr, NaN), 'heading'],
+    ['groundspeed', (dr) => ResultFormatter.groundspeed(dr, NaN), 'groundspeed'],
+    ['airspeed', (dr) => ResultFormatter.airspeed(dr, NaN), 'airspeed'],
+    ['mach', (dr) => ResultFormatter.mach(dr, NaN), 'mach'],
+    ['day', (dr) => ResultFormatter.day(dr, NaN), 'day'],
+    ['month', (dr) => ResultFormatter.month(dr, NaN), 'month'],
+    ['departureDay', (dr) => ResultFormatter.departureDay(dr, NaN), 'departure_day'],
+    ['arrivalDay', (dr) => ResultFormatter.arrivalDay(dr, NaN), 'arrival_day'],
+  ];
+
+  test.each(cases)(
+    '%s skips NaN instead of pushing a "NaN" item',
+    (_name, invoke, rawKey) => {
+      const dr = makeDecodeResult();
+      invoke(dr);
+      expect(dr.formatted.items.length).toBe(0);
+      expect((dr.raw as Record<string, unknown>)[rawKey]).toBeUndefined();
+    },
+  );
+
+  test('heading still formats a valid value', () => {
+    const dr = makeDecodeResult();
+    ResultFormatter.heading(dr, 270);
+    expect(dr.raw.heading).toBe(270);
+    expect(dr.formatted.items[0].value).toBe('270');
+  });
+
+  test('groundspeed still formats a valid value', () => {
+    const dr = makeDecodeResult();
+    ResultFormatter.groundspeed(dr, 420);
+    expect(dr.raw.groundspeed).toBe(420);
+    expect(dr.formatted.items[0].value).toBe('420 knots');
+  });
+
+  test('mach still formats a valid value', () => {
+    const dr = makeDecodeResult();
+    ResultFormatter.mach(dr, 0.84);
+    expect(dr.raw.mach).toBe(0.84);
+    expect(dr.formatted.items[0].value).toBe('0.84 mach');
+  });
+
+  test('day still formats a valid value', () => {
+    const dr = makeDecodeResult();
+    ResultFormatter.day(dr, 12);
+    expect(dr.raw.day).toBe(12);
+    expect(dr.formatted.items[0].value).toBe('12');
+  });
+});
diff --git a/lib/utils/result_formatter.ts b/lib/utils/result_formatter.ts
index 515d4c4..1fddc18 100644
--- a/lib/utils/result_formatter.ts
+++ b/lib/utils/result_formatter.ts
@@ -303,6 +303,9 @@ export class ResultFormatter {
   }
 
   static groundspeed(decodeResult: DecodeResult, value: number) {
+    if (isNaN(value)) {
+      return;
+    }
     decodeResult.raw.groundspeed = value;
     decodeResult.formatted.items.push({
       type: 'aircraft_groundspeed',
@@ -313,6 +316,9 @@ export class ResultFormatter {
   }
 
   static airspeed(decodeResult: DecodeResult, value: number) {
+    if (isNaN(value)) {
+      return;
+    }
     decodeResult.raw.airspeed = value;
     decodeResult.formatted.items.push({
       type: 'airspeed',
@@ -323,6 +329,9 @@ export class ResultFormatter {
   }
 
   static mach(decodeResult: DecodeResult, value: number) {
+    if (isNaN(value)) {
+      return;
+    }
     decodeResult.raw.mach = value;
     decodeResult.formatted.items.push({
       type: 'mach',
@@ -363,6 +372,9 @@ export class ResultFormatter {
   }
 
   static heading(decodeResult: DecodeResult, value: number) {
+    if (isNaN(value)) {
+      return;
+    }
     decodeResult.raw.heading = value;
     decodeResult.formatted.items.push({
       type: 'heading',
@@ -460,6 +472,9 @@ export class ResultFormatter {
   }
 
   static day(decodeResult: DecodeResult, day: number) {
+    if (isNaN(day)) {
+      return;
+    }
     decodeResult.raw.day = day;
     decodeResult.formatted.items.push({
       type: 'day',
@@ -470,6 +485,9 @@ export class ResultFormatter {
   }
 
   static month(decodeResult: DecodeResult, month: number) {
+    if (isNaN(month)) {
+      return;
+    }
     decodeResult.raw.month = month;
     decodeResult.formatted.items.push({
       type: 'month',
@@ -480,6 +498,9 @@ export class ResultFormatter {
   }
 
   static departureDay(decodeResult: DecodeResult, day: number) {
+    if (isNaN(day)) {
+      return;
+    }
     decodeResult.raw.departure_day = day;
     decodeResult.formatted.items.push({
       type: 'day',
@@ -490,6 +511,9 @@ export class ResultFormatter {
   }
 
   static arrivalDay(decodeResult: DecodeResult, day: number) {
+    if (isNaN(day)) {
+      return;
+    }
     decodeResult.raw.arrival_day = day;
     decodeResult.formatted.items.push({
       type: 'day',