Add dataurl alias of url (elastic#646)

* [Image] Change dataurl to url, dataurl is an alias for bwc

* update tests

* dataurl won't be an arg because it's aliased to url

* make url the alias, keep dataurl as the primary

* revert a pulled-out change and comment

common/functions/__tests__/image.js

@@ -14,11 +14,18 @@ describe('image', () => {
 
   describe('args', () => {
     describe('dataurl', () => {
-      it('sets the source of the image', () => {
+      it('sets the source of the image using dataurl', () => {
         const result = fn(null, { dataurl: elasticOutline });
         expect(result).to.have.property('dataurl', elasticOutline);
       });
 
+      it.skip('sets the source of the image using url', () => {
+        // This is skipped because functionWrapper doesn't use the actual
+        // interpreter and doesn't resolve aliases
+        const result = fn(null, { url: elasticOutline });
+        expect(result).to.have.property('dataurl', elasticOutline);
+      });
+
       it('defaults to the elasticLogo if not provided', () => {
         const result = fn(null);
         expect(result).to.have.property('dataurl', elasticLogo);
@@ -27,25 +34,25 @@ describe('image', () => {
 
     describe('mode', () => {
       it('sets the mode', () => {
-        it('returns an image object using a dataUrl', () => {
+        it('to contain', () => {
           const result = fn(null, { mode: 'contain' });
           expect(result).to.have.property('mode', 'contain');
         });
 
-        it('returns an image object using a dataUrl', () => {
+        it('to cover', () => {
           const result = fn(null, { mode: 'cover' });
           expect(result).to.have.property('mode', 'cover');
         });
 
-        it('returns an image object using a dataUrl', () => {
+        it('to stretch', () => {
           const result = fn(null, { mode: 'stretch' });
           expect(result).to.have.property('mode', 'stretch');
         });
-      });
 
-      it("defaults to 'contain' if not provided", () => {
-        const result = fn(null);
-        expect(result).to.have.property('mode', 'contain');
+        it("defaults to 'contain' if not provided", () => {
+          const result = fn(null);
+          expect(result).to.have.property('mode', 'contain');
+        });
       });
     });
   });

common/functions/image/image.js

@@ -15,7 +15,7 @@ export const image = () => ({
       // This was accepting dataurl, but there was no facility in fn for checking type and handling a dataurl type.
       types: ['string', 'null'],
       help: 'Base64 encoded image',
-      aliases: ['_'],
+      aliases: ['_', 'url'],
       default: elasticLogo,
     },
     mode: {
@@ -27,16 +27,16 @@ export const image = () => ({
       default: 'contain',
     },
   },
-  fn: (context, args) => {
-    if (!includes(['contain', 'cover', 'stretch'], args.mode))
+  fn: (context, { dataurl, mode }) => {
+    if (!includes(['contain', 'cover', 'stretch'], mode))
       throw '"mode" must be "contain", "cover", or "stretch"';
 
-    const mode = args.mode === 'stretch' ? '100% 100%' : args.mode;
+    const modeStyle = mode === 'stretch' ? '100% 100%' : mode;
 
     return {
       type: 'image',
-      mode,
-      dataurl: resolveWithMissingImage(args.dataurl, elasticLogo),
+      mode: modeStyle,
+      dataurl: resolveWithMissingImage(dataurl, elasticLogo),
     };
   },
 });

common/lib/resolve_dataurl.js

@@ -2,6 +2,11 @@ import { get } from 'lodash';
 import { isValid } from '../../common/lib/dataurl';
 import { missingImage } from '../../common/lib/missing_asset';
 
+/*
+ * NOTE: args.dataurl can come as an expression here.
+ * For example:
+ *   [{"type":"expression","chain":[{"type":"function","function":"asset","arguments":{"_":["..."]}}]}]
+ */
 export const resolveFromArgs = (args, defaultDataurl = null) => {
   const dataurl = get(args, 'dataurl.0', null);
   return isValid(dataurl) ? dataurl : defaultDataurl;