Units separated to their own block, and properly tested

test/unit/units.js

@@ -0,0 +1,48 @@
+const u = require('../../src/units')
+
+describe('Units', function() {
+
+    it('defaults', function() {
+        // check that an empty config has the default units (and nothing more)
+        const def = u.parse({})
+        Object.keys(def).length.should.equal(3)
+        def.u.should.equal(19)
+        def.cx.should.equal(18)
+        def.cy.should.equal(17)
+    })
+
+    it('units', function() {
+        // check that units can contain formulas, and reference each other
+        const res = u.parse({
+            units: {
+                a: 'cx / 2',
+                b: 'a + 1'
+            }
+        })
+        Object.keys(res).length.should.equal(5)
+        res.a.should.equal(9)
+        res.b.should.equal(10)
+        // also check that order matters, which it should
+        u.parse.bind(this, {
+            units: {
+                a: 'b + 1',
+                b: 'cx / 2'
+            }
+        }).should.throw()
+    })
+
+    it('variables', function() {
+        // check that variables work, and can override units
+        const res = u.parse({
+            units: {
+                a: 'cx / 2',
+            },
+            variables: {
+                a: 'u + 1'
+            }
+        })
+        Object.keys(res).length.should.equal(4)
+        res.a.should.equal(20)
+    })
+
+})