From dd5aeb529b8b261d6b64d3aac25f0fa55fe30df8 Mon Sep 17 00:00:00 2001
From: Teppo Kurki <teppo.kurki@iki.fi>
Date: Fri, 17 Sep 2021 23:08:27 +0300
Subject: [PATCH] fix: guard against 0 revs in propslip (#93)

Adds also minimal test for this.
---
 calcs/propslip.js | 52 ++++++++++++++++++++++++++++++++++++++++-------
 test/test.js      | 21 ++++++++++++-------
 2 files changed, 59 insertions(+), 14 deletions(-)

diff --git a/calcs/propslip.js b/calcs/propslip.js
index 3d88572..f174a59 100644
--- a/calcs/propslip.js
+++ b/calcs/propslip.js
@@ -1,5 +1,24 @@
 const _ = require('lodash')
 
+const selfData = {
+  propulsion: {
+    port: {
+      transmission: {
+        gearRatio: {
+          value: 1
+        }
+      },
+      drive: {
+        propeller: {
+          pitch: {
+            value: 1
+          }
+        }
+      }
+    }
+  }
+}
+
 module.exports = function (app, plugin) {
   return plugin.engines.map(instance => {
     return {
@@ -26,13 +45,32 @@ module.exports = function (app, plugin) {
         var pitch = app.getSelfPath(
           'propulsion.' + instance + '.drive.propeller.pitch.value'
         )
-        return [
-          {
-            path: 'propulsion.' + instance + '.drive.propeller.slip',
-            value: 1 - stw * gearRatio / (revolutions * pitch)
-          }
-        ]
-      }
+        if (revolutions > 0) {
+          return [
+            {
+              path: 'propulsion.' + instance + '.drive.propeller.slip',
+              value: 1 - stw * gearRatio / (revolutions * pitch)
+            }
+          ]
+        }
+      },
+      tests: [
+        {
+          input: [0, 1],
+          selfData,
+          expected: undefined
+        },
+        {
+          input: [2, 1],
+          selfData,
+          expected: [
+            {
+              path: 'propulsion.port.drive.propeller.slip',
+              value: 0.5
+            }
+          ]
+        }
+      ]
     }
   })
 }
diff --git a/test/test.js b/test/test.js
index 10b8697..90aa0ef 100644
--- a/test/test.js
+++ b/test/test.js
@@ -5,19 +5,21 @@ const chai = require('chai')
 chai.Should()
 chai.use(require('chai-json-equal'));
 
+let selfData = {}
+
 const app = {
-  debug: () => {},
-  getSelfPath: (path) => {}
+  debug: () => { },
+  getSelfPath: (path) => _.get(selfData, path)
 }
 
 const plugin = {
-  batteries: [ '0', '1' ],
-  engines: [ 'port' ],
+  batteries: ['0', '1'],
+  engines: ['port'],
   tanks: ['fuel'],
   air: ['outside']
 }
 
-function load_calcs () {
+function load_calcs() {
   fpath = path.join(__dirname, '../calcs')
   files = fs.readdirSync(fpath)
   return files
@@ -37,11 +39,16 @@ describe('derived data converts', function () {
 
   calcs.forEach(calci => {
     (_.isArray(calci) ? calci : [calci]).forEach(calc => {
-      if ( calc.tests ) {
+      if (calc.tests) {
         calc.tests.forEach((test, idx) => {
           it(`${calc.title}[${idx}] works`, (done) => {
+            selfData = test.selfData || {}
             let res = calc.calculator.apply(null, test.input)
-            res.should.jsonEqual(test.expected)
+            if (test.expected) {
+              res.should.jsonEqual(test.expected)
+            } else {
+              (typeof res).should.equal('undefined')
+            }
             done()
           })
         })