Fix ::delete method to return true also if key does not exists

README.md

@@ -87,6 +87,12 @@ It is a bad decision?
 I leave the decision to you :-D
 I think this method is not necessary, but I decided to leave it there for the sake of completeness.
 
+### The return value of the `Class::delete()` method
+
+As always in WordPress there is no real standard between API (f**k), and the `Class::delete()` method is another example about this.
+The `\remove_theme_mod()` is the only function that does not return anything, all the other functions return `true` if the value has been deleted or `false` if the value does not exist.
+Now, to make this more similar to the PSR-16 specification, the `Class::delete()` method return `true` if the value has been deleted and if the value does not exist, the only way to return a false value is to provide an empty string as the key.
+
 ## Basic Usage
 
 Remember that the maximum length of the key used for [transients](https://developer.wordpress.org/reference/functions/set_transient/) is <=172 characters, more characters will rise an Exception.

src/Cache.php

@@ -50,6 +50,14 @@ public function update(string $key, $value, ?int $ttl = null): bool
 
     public function delete(string $key): bool
     {
+        if (empty($key)) {
+            return false;
+        }
+
+        if (!$this->get($key)) {
+            return true;
+        }
+
         return \wp_cache_delete($key, $this->group);
     }
 
@@ -112,10 +120,9 @@ public function getMultiple(iterable $keys, $default = null): iterable
 
     public function deleteMultiple(iterable $keys): bool
     {
-        $newValues = $this->iteratorToArray($keys);
-        $result = \wp_cache_delete_multiple($newValues, $this->group);
-        foreach ($result as $value) {
-            if (!$value) {
+        /** @var string $key */
+        foreach ($keys as $key) {
+            if (!$this->delete($key)) {
                 return false;
             }
         }

src/MultipleTrait.php

@@ -34,10 +34,9 @@ public function deleteMultiple(iterable $keys): bool
     {
         /** @var string[] $keys */
         foreach ($keys as $key) {
-            if ($this->delete($key)) {
-                continue;
+            if (!$this->delete($key)) {
+                return false;
             }
-            return false;
         }
 
         return true;

src/Option.php

@@ -50,6 +50,14 @@ public function update(string $key, $value): bool
      */
     public function delete(string $key): bool
     {
+        if (empty($key)) {
+            return false;
+        }
+
+        if (!$this->get($key)) {
+            return true;
+        }
+
         return \delete_option($key);
     }
 }

src/Transient.php

@@ -43,7 +43,14 @@ public function update(string $key, $value, ?int $ttl = null): bool
 
     public function delete(string $key): bool
     {
-        $this->assertKeyLength($key);
+        if (empty($key)) {
+            return false;
+        }
+
+        if (!$this->get($key)) {
+            return true;
+        }
+
         return \delete_transient($key);
     }
 }

tests/src/CommonTrait.php

@@ -108,10 +108,28 @@ public function deleteMultiple(iterable $keys, iterable $expected = [])
     /**
      * @test
      */
-    public function deleteMultipleReturnFalse()
+    public function deleteMultipleReturnTrueWithNotExistentValue()
     {
         $this->assertNull($this->makeInstance()->get('key1'));
         $this->assertNull($this->makeInstance()->get('key3'));
-        $this->assertFalse($this->makeInstance()->deleteMultiple(['key1', 'key3']), '');
+        $this->assertTrue($this->makeInstance()->deleteMultiple(['key1', 'key3']), '');
+    }
+
+    /**
+     * @test
+     * @todo In the future make this test pass
+     */
+    public function deleteNotExistingValue()
+    {
+        $this->assertTrue($this->makeInstance()->delete('key1'), '');
+    }
+
+    /**
+     * @test
+     */
+    public function deleteFromEmptyKeyShouldReturnFalse()
+    {
+        $this->assertFalse($this->makeInstance()->delete(''), '');
+        $this->assertFalse($this->makeInstance()->deleteMultiple(['']), '');
     }
 }

tests/src/ModTestTrait.php

@@ -79,4 +79,13 @@ public function deleteMultipleReturnFalse()
         // Deleting a theme mod will always return true even if the mod doesn't exist
         $this->assertTrue($this->makeInstance()->deleteMultiple(['key1', 'key3']), '');
     }
+
+    /**
+     * @test
+     */
+    public function deleteFromEmptyKeyShouldReturnFalse()
+    {
+        $this->assertTrue($this->makeInstance()->delete(''), '');
+        $this->assertTrue($this->makeInstance()->deleteMultiple(['']), '');
+    }
 }

tests/src/TestCase.php

@@ -172,6 +172,7 @@ protected function _after() {
         $this->store = [];
         $this->set_return_value = true;
         $this->delete_return_value = true;
+        $this->ttl = 0;
 //        $this->prophet->checkPredictions();
     }