From 62712e8a4cee7c1165fc318955efe48d0e123eaf Mon Sep 17 00:00:00 2001
From: Axel Gross <axel.gross@digiconcept.net>
Date: Wed, 22 Nov 2017 12:09:13 +0100
Subject: [PATCH 1/2] Prototype diff formatting for discussion

Feature request:

It would be good to be able to see not only that actual and expected results are different,
but also one would like to see in which way they differ.

I couldnt find a way to extend leo for diffing in plugin-kind of way. So I started prototyping.

This commit prototypes a possible implementation with the following properties
* Because the relevant different depends on the type of matcher,
  each matcher supporting diffs (see SameMatcher) gets a $differ method to be called by the formatter
* also the matcher adds a "diff" to the format template vars
* on match, the abstract matcher adds the differ to match the result iff the result is unexpected
* Formatter reads and prints the $diff member from the matcher
* diffing is actually not implemented, that probably should be plugged in using a thirdparty lib

This indicates
* leo probably should not force diff calculation on users
* there should be a kind of extension point to add a differ implementation

So this bears the questions:
* is there a way already to hook in diffing?
* is there a better place than Matcher/Match/Formatter ?
** should diff calculation happen when matching or when formatting
* where/how would I register a Differ?
* should the Differ be added as mix-in on the Matchers?
---
 src/Formatter/Formatter.php     | 1 +
 src/Matcher/AbstractMatcher.php | 7 ++++++-
 src/Matcher/SameMatcher.php     | 6 +++++-
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/Formatter/Formatter.php b/src/Formatter/Formatter.php
index 68ad935..b742210 100644
--- a/src/Formatter/Formatter.php
+++ b/src/Formatter/Formatter.php
@@ -98,6 +98,7 @@ protected function getTemplateVars(TemplateInterface $template)
         $vars = [
             'expected' => $this->match->getExpected(),
             'actual' => $this->match->getActual(),
+            'diff' => is_callable($this->match->differ)?call_user_func($this->match->differ, $this->match->getActual(), $this->match->getExpected()):""
         ];
 
         if ($tplVars = $template->getTemplateVars()) {
diff --git a/src/Matcher/AbstractMatcher.php b/src/Matcher/AbstractMatcher.php
index 033ff79..57d9889 100644
--- a/src/Matcher/AbstractMatcher.php
+++ b/src/Matcher/AbstractMatcher.php
@@ -31,8 +31,13 @@ public function match($actual = '')
     {
         $isMatch = $this->doMatch($actual);
         $isNegated = $this->isNegated();
+        $fulfillsExpectation = ($isMatch xor $isNegated);
 
-        return new Match($isMatch xor $isNegated, $this->expected, $actual, $isNegated);
+        $match = new Match($fulfillsExpectation, $this->expected, $actual, $isNegated);
+        if ((!$fulfillsExpectation) && method_exists($this, "differ")) {
+            $match->differ = [$this, "differ"];
+        }
+        return $match;
     }
 
     /**
diff --git a/src/Matcher/SameMatcher.php b/src/Matcher/SameMatcher.php
index 62a64dc..118c249 100644
--- a/src/Matcher/SameMatcher.php
+++ b/src/Matcher/SameMatcher.php
@@ -11,6 +11,10 @@
  */
 class SameMatcher extends AbstractMatcher
 {
+    public function differ($actual, $expected) {
+        return "THE CALCULATED DIFF";
+    }
+
     /**
      * Match if the actual value is identical to the expected value using an ===
      * comparison.
@@ -31,7 +35,7 @@ public function doMatch($actual)
     public function getDefaultTemplate()
     {
         return new ArrayTemplate([
-            'default' => 'Expected {{actual}} to be identical to {{expected}}',
+            'default' => 'Expected {{actual}} to be identical to {{expected}}. Difference: {{diff}}',
             'negated' => 'Expected {{actual}} not to be identical to {{expected}}',
         ]);
     }

From 12c7082700c04ec2d1e33afc8e34412e821e7421 Mon Sep 17 00:00:00 2001
From: Axel Gross <axel.gross@iaeste.at>
Date: Wed, 5 Feb 2020 16:07:10 +0100
Subject: [PATCH 2/2] Make specs happy

---
 src/Formatter/Formatter.php | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
 mode change 100644 => 100755 src/Formatter/Formatter.php

diff --git a/src/Formatter/Formatter.php b/src/Formatter/Formatter.php
old mode 100644
new mode 100755
index b742210..f1164db
--- a/src/Formatter/Formatter.php
+++ b/src/Formatter/Formatter.php
@@ -95,10 +95,11 @@ public function objectToString($obj)
      */
     protected function getTemplateVars(TemplateInterface $template)
     {
+        $differExists = (property_exists($this->match, "differ") && is_callable($this->match->differ));
         $vars = [
             'expected' => $this->match->getExpected(),
             'actual' => $this->match->getActual(),
-            'diff' => is_callable($this->match->differ)?call_user_func($this->match->differ, $this->match->getActual(), $this->match->getExpected()):""
+            'diff' => $differExists?call_user_func($this->match->differ, $this->match->getActual(), $this->match->getExpected()):"",
         ];
 
         if ($tplVars = $template->getTemplateVars()) {