dev(errors): better errors WIP

WIP of fixing https://github.com/manuelbieh/geolib/issues/203\#issuecomment-508910464

.npmrc

@@ -1 +0,0 @@
-//registry.npmjs.org/:_authToken = ${NPM_TOKEN}

src/validateCoords.test.js

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+import validateCoords from './validateCoords';
+
+const spy = jest.spyOn(console, 'error');
+
+afterEach(() => {
+    spy.mockRestore();
+});
+
+describe('validateCoords', () => {
+    it('should log errors in the console for invalid from/to coords', () => {
+        validateCoords({ from: {}, to: {} });
+        expect(spy).toHaveBeenCalledTimes(4);
+    });
+
+    it('should NOT log errors in the console for valid from/to coords', () => {
+        expect(spy).toHaveBeenCalledTimes(0);
+        let from = { lat: 1, lng: 1 };
+        let to = { lat: 2, lng: 2 };
+        validateCoords({ from, to });
+        expect(spy).toHaveBeenCalledTimes(0);
+        from = { latitude: 1, longitude: 1 };
+        to = { latitude: 2, longitude: 2 };
+        validateCoords({ from, to });
+        expect(spy).toHaveBeenCalledTimes(0);
+        from = { latitude: 1, lon: 1 };
+        to = { latitude: 2, lon: 2 };
+        validateCoords({ from, to });
+        expect(spy).toHaveBeenCalledTimes(0);
+    });
+});

src/validateCoords.ts

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+const lonKeys = ['lng', 'lon', 'longitude'];
+const latKeys = ['lat', 'latitude'];
+const typesRegex = /number|string/;
+
+const isLongValid = (arg) =>
+    !!lonKeys.find((key) => (typeof arg[key]).match(typesRegex));
+
+const isLatValid = (arg) =>
+    !!latKeys.find((key) => (typeof arg[key]).match(typesRegex));
+
+const reportInvalid = (arg, fromOrTo, latOrLong) =>
+    console.error(
+        `[geolib] -> Get distance -> ${latOrLong} invalid for object "${fromOrTo}". expected property lng, lon or longitude to be present and have type of string or number, but received:`,
+        arg
+    );
+
+const validateLong = (arg, fromOrTo) => {
+    if (!isLongValid(arg)) {
+        reportInvalid(arg, fromOrTo, 'longitude');
+    }
+};
+
+const validateLat = (arg, fromOrTo) => {
+    if (!isLatValid(arg)) {
+        reportInvalid(arg, fromOrTo, 'latitude');
+    }
+};
+
+const validateCoords = ({ from, to }) => {
+    validateLat(from, 'from');
+    validateLong(from, 'from');
+    validateLat(to, 'to');
+    validateLong(to, 'to');
+};
+
+export default validateCoords;