fix: MWV angles should be positive

Also add tests.

nmea.js

@@ -132,12 +132,21 @@ function fixAngle (d) {
   return result
 }
 
+function toPositiveRadians (d) {
+  return d < 0 ? d + 2 * Math.PI : d
+}
+
+function radsToPositiveDeg(r) {
+  return radsToDeg(toPositiveRadians(r))
+}
+
 module.exports = {
   toSentence: toSentence,
   radsToDeg: radsToDeg,
   msToKnots: msToKnots,
   msToKM: msToKM,
   toNmeaDegreesLatitude: toNmeaDegreesLatitude,
   toNmeaDegreesLongitude: toNmeaDegreesLongitude,
-  fixAngle: fixAngle
+  fixAngle: fixAngle,
+  radsToPositiveDeg
 }

sentences/MWVR.js

@@ -26,7 +26,7 @@ module.exports = function (app) {
     f: function (angle, speed) {
       return nmea.toSentence([
         '$INMWV',
-        nmea.radsToDeg(angle).toFixed(2),
+        nmea.radsToPositiveDeg(angle).toFixed(2),
         'R',
         speed.toFixed(2),
         'M',

sentences/MWVT.js

@@ -9,7 +9,7 @@ module.exports = function (app) {
     f: function (angle, speed) {
       return nmea.toSentence([
         '$INMWV',
-        nmea.radsToDeg(angle).toFixed(2),
+        nmea.radsToPositiveDeg(angle).toFixed(2),
         'T',
         speed.toFixed(2),
         'M',

test/MWV.js

@@ -0,0 +1,57 @@
+const assert = require('assert')
+
+const { createAppWithPlugin } = require('./testutil')
+
+describe('MWV relative', function () {
+  it('works with positive angle', done => {
+    const onEmit = (event, value) => {
+      assert.equal(value, '$INMWV,180.00,R,2.00,M,A*32')
+      done()
+    }
+    const app = createAppWithPlugin(onEmit, 'MWVR')
+    app.streambundle
+      .getSelfStream('environment.wind.angleApparent')
+      .push(Math.PI)
+    app.streambundle.getSelfStream('environment.wind.speedApparent').push(2)
+  })
+
+  it('works with negative angle', done => {
+    const onEmit = (event, value) => {
+      assert.equal(value, '$INMWV,270.00,R,2.00,M,A*3E')
+      done()
+    }
+    const app = createAppWithPlugin(onEmit, 'MWVR')
+    app.streambundle
+      .getSelfStream('environment.wind.angleApparent')
+      .push(-Math.PI / 2)
+    app.streambundle.getSelfStream('environment.wind.speedApparent').push(2)
+  })
+})
+
+describe('MWV true', function () {
+  it('works with positive angle', done => {
+    const onEmit = (event, value) => {
+      assert.equal(value, '$INMWV,180.00,T,2.00,M,A*34')
+      done()
+    }
+
+    const app = createAppWithPlugin(onEmit, 'MWVT')
+    app.streambundle
+      .getSelfStream('environment.wind.angleTrueWater')
+      .push(Math.PI)
+    app.streambundle.getSelfStream('environment.wind.speedTrue').push(2)
+  })
+
+  it('works with negative angle', done => {
+    const onEmit = (event, value) => {
+      assert.equal(value, '$INMWV,270.00,T,2.00,M,A*38')
+      done()
+    }
+
+    const app = createAppWithPlugin(onEmit, 'MWVT')
+    app.streambundle
+      .getSelfStream('environment.wind.angleTrueWater')
+      .push(-Math.PI / 2)
+    app.streambundle.getSelfStream('environment.wind.speedTrue').push(2)
+  })
+})