From 7b4a9a43b0cec4889bc12375a5f030a22885c735 Mon Sep 17 00:00:00 2001
From: Bryan Housel <bryan@mapbox.com>
Date: Thu, 2 May 2019 22:59:41 -0400
Subject: [PATCH] Change `utilTagDiff` to return an object with details

---
 modules/util/util.js                 | 16 ++++++++++++++--
 modules/validations/outdated_tags.js |  4 ++--
 modules/validations/private_data.js  |  4 ++--
 test/spec/util/util.js               | 16 ++++++++++++----
 4 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/modules/util/util.js b/modules/util/util.js
index ea8d477da..a5bfc2534 100644
--- a/modules/util/util.js
+++ b/modules/util/util.js
@@ -22,10 +22,22 @@ export function utilTagDiff(oldTags, newTags) {
         var newVal = newTags[k];
 
         if (oldVal && (!newVal || newVal !== oldVal)) {
-            tagDiff.push('- ' + k + '=' + oldVal);
+            tagDiff.push({
+                type: '-',
+                key: k,
+                oldVal: oldVal,
+                newVal: newVal,
+                display: '- ' + k + '=' + oldVal
+            });
         }
         if (newVal && (!oldVal || newVal !== oldVal)) {
-            tagDiff.push('+ ' + k + '=' + newVal);
+            tagDiff.push({
+                type: '+',
+                key: k,
+                oldVal: oldVal,
+                newVal: newVal,
+                display: '+ ' + k + '=' + newVal
+            });
         }
     });
     return tagDiff;
diff --git a/modules/validations/outdated_tags.js b/modules/validations/outdated_tags.js
index d73ed0b77..e3336e68d 100644
--- a/modules/validations/outdated_tags.js
+++ b/modules/validations/outdated_tags.js
@@ -99,10 +99,10 @@ export function validationOutdatedTags() {
                 .attr('class', 'tagDiff-row')
                 .append('td')
                 .attr('class', function(d) {
-                    var klass = d.charAt(0) === '+' ? 'add' : 'remove';
+                    var klass = d.type === '+' ? 'add' : 'remove';
                     return 'tagDiff-cell tagDiff-cell-' + klass;
                 })
-                .text(function(d) { return d; });
+                .text(function(d) { return d.display; });
         }
     }
 
diff --git a/modules/validations/private_data.js b/modules/validations/private_data.js
index 972e77dec..15c6ae5b7 100644
--- a/modules/validations/private_data.js
+++ b/modules/validations/private_data.js
@@ -107,10 +107,10 @@ export function validationPrivateData() {
                 .attr('class', 'tagDiff-row')
                 .append('td')
                 .attr('class', function(d) {
-                    var klass = d.charAt(0) === '+' ? 'add' : 'remove';
+                    var klass = d.type === '+' ? 'add' : 'remove';
                     return 'tagDiff-cell tagDiff-cell-' + klass;
                 })
-                .text(function(d) { return d; });
+                .text(function(d) { return d.display; });
         }
     };
 
diff --git a/test/spec/util/util.js b/test/spec/util/util.js
index 3811273be..63b999955 100644
--- a/test/spec/util/util.js
+++ b/test/spec/util/util.js
@@ -58,10 +58,18 @@ describe('iD.util', function() {
         var newTags = { a: 'one', b: 'three', d: 'four' };
         var diff = iD.utilTagDiff(oldTags, newTags);
         expect(diff).to.have.length(4);
-        expect(diff[0]).to.eql('- b=two');    // delete-modify
-        expect(diff[1]).to.eql('+ b=three');  // insert-modify
-        expect(diff[2]).to.eql('- c=three');  // delete
-        expect(diff[3]).to.eql('+ d=four');   // insert
+        expect(diff[0]).to.eql({
+            type: '-', key: 'b', oldVal: 'two', newVal: 'three', display: '- b=two'        // delete-modify
+        });
+        expect(diff[1]).to.eql({
+            type: '+', key: 'b', oldVal: 'two', newVal: 'three', display: '+ b=three'      // insert-modify
+        });
+        expect(diff[2]).to.eql({
+            type: '-', key: 'c', oldVal: 'three', newVal: undefined, display: '- c=three'  // delete
+        });
+        expect(diff[3]).to.eql({
+            type: '+', key: 'd', oldVal: undefined, newVal: 'four', display: '+ d=four'    // insert
+        });
     });
 
     it('utilTagText', function() {