Return null if put/deleteIf fails because no previous value exists

src/Storage/EtcdStorage.php

@@ -17,24 +17,35 @@ public function __construct(?ClientInterface $client = null)
         $this->client = $client ?? new Client();
     }
 
-    public function putIf(string $key, string $value, ?string $previousValue, bool $returnNewValueOnFail = false): bool|string
+    public function putIf(string $key, string $value, ?string $previousValue, bool $returnNewValueOnFail = false): bool|string|null
     {
         try {
-            return $this->client->putIf($key, $value, $previousValue ?? false, $returnNewValueOnFail);
+            $result = $this->client->putIf($key, $value, $previousValue ?? false, $returnNewValueOnFail);
         } catch (UnavailableException | DeadlineExceededException | UnknownException $e) {
             throw new StorageException($e->getMessage(), $e->getCode(), $e);
         }
+
+        if ($returnNewValueOnFail && $result === false) {
+            return null;
+        }
+
+        return $result;
     }
 
-    public function deleteIf(string $key, ?string $previousValue, bool $returnNewValueOnFail = false): bool|string
+    public function deleteIf(string $key, ?string $previousValue, bool $returnNewValueOnFail = false): bool|string|null
     {
         try {
-            return $this->client->deleteIf($key, $previousValue ?? false, $returnNewValueOnFail);
+            $result = $this->client->deleteIf($key, $previousValue ?? false, $returnNewValueOnFail);
         } catch (UnavailableException | DeadlineExceededException | UnknownException $e) {
             throw new StorageException($e->getMessage(), $e->getCode(), $e);
         }
-    }
 
+        if ($returnNewValueOnFail && $result === false) {
+            return null;
+        }
+
+        return $result;
+    }
 
     public function get(string $key): ?string
     {

src/Storage/StorageInterface.php

@@ -17,12 +17,12 @@ interface StorageInterface
      * @param string|null $previousValue The previous value to compare against. If null is provided, the comparison
      * should check that the key does not exist yet.
      * @param bool $returnNewValueOnFail if true the new value of the key should be returned if the operation fails
-     * @return bool|string true if the operation succeeded, false if it failed and `$returnNewValueOnFail` is false,
-     * otherwise the new value of the key
+     * @return bool|string|null true if the operation succeeded, false if it failed and `$returnNewValueOnFail` is
+     * false, otherwise the new value of the key
      * @throws StorageException a known, retryable error occurred
      * @throws Exception an unknown error occurred
      */
-    public function putIf(string $key, string $value, ?string $previousValue, bool $returnNewValueOnFail): bool|string;
+    public function putIf(string $key, string $value, ?string $previousValue, bool $returnNewValueOnFail): bool|string|null;
 
     /**
      * Delete if $key value matches $previous value otherwise $returnNewValueOnFail
@@ -31,12 +31,12 @@ public function putIf(string $key, string $value, ?string $previousValue, bool $
      * @param string|null $previousValue The previous value to compare against. If null is provided, the comparison
      *  should check that the key does not exist yet.
      * @param bool $returnNewValueOnFail
-     * @return bool|string true if the operation succeeded, false if it failed and `$returnNewValueOnFail` is false,
-     * otherwise the new value of the key
+     * @return bool|string|null true if the operation succeeded, false if it failed and `$returnNewValueOnFail` is
+     * false, otherwise the new value of the key
      * @throws StorageException a known, retryable error occurred
      * @throws Exception an unknown error occurred
      */
-    public function deleteIf(string $key, ?string $previousValue, bool $returnNewValueOnFail = false): bool|string;
+    public function deleteIf(string $key, ?string $previousValue, bool $returnNewValueOnFail = false): bool|string|null;
 
     /**
      * Get the value of a key

test/Storage/EtcdStorageTest.php

@@ -31,9 +31,9 @@ protected function equalToEtcdValue(?string $x): IsEqual
 
     #[TestWith(['previous_value', false])]
     #[TestWith(['previous_value', true])]
-    #[TestWith(['previous_value', "real-previous-value"])]
     #[TestWith([null, false])]
-    public function testPutIf(?string $previousValue, bool|string $result): void
+    #[TestWith([null, true])]
+    public function testPutIf(?string $previousValue, bool $result): void
     {
         $key = 'test_key';
         $value = 'test_value';
@@ -43,7 +43,28 @@ public function testPutIf(?string $previousValue, bool|string $result): void
             ->with($this->equalTo($key), $this->equalTo($value), $this->equalToEtcdValue($previousValue))
             ->willReturn($result);
 
-        $this->assertEquals($result, $this->storage->putIf($key, $value, $previousValue));
+        $this->assertSame($result, $this->storage->putIf($key, $value, $previousValue));
+    }
+
+    #[TestWith(['previous_value', false, null])]
+    #[TestWith(['previous_value', true, true])]
+    #[TestWith([null, 'real_value', 'real_value'])]
+    #[TestWith([null, true, true])]
+    public function testPutIfReturnValue(
+        ?string $previousValue,
+        bool|string $etcdResponse,
+        bool|string|null $expected,
+    ): void
+    {
+        $key = 'test_key';
+        $value = 'test_value';
+
+
+        $this->client->method('putIf')
+            ->with($this->equalTo($key), $this->equalTo($value), $this->equalToEtcdValue($previousValue))
+            ->willReturn($etcdResponse);
+
+        $this->assertSame($expected, $this->storage->putIf($key, $value, $previousValue, true));
     }
 
     public function testPutIfStorageException(): void
@@ -78,8 +99,8 @@ public function testPutIfOtherException(): void
 
     #[TestWith(['previous_value', false])]
     #[TestWith(['previous_value', true])]
-    #[TestWith(['previous_value', "real-previous-value"])]
     #[TestWith([null, false])]
+    #[TestWith([null, true])]
     public function testDeleteIf(?string $previousValue, bool|string $result): void
     {
         $key = 'test_key';
@@ -88,7 +109,26 @@ public function testDeleteIf(?string $previousValue, bool|string $result): void
             ->with($this->equalTo($key), $this->equalToEtcdValue($previousValue))
             ->willReturn($result);
 
-        $this->assertEquals($result, $this->storage->deleteIf($key, $previousValue));
+        $this->assertSame($result, $this->storage->deleteIf($key, $previousValue));
+    }
+
+    #[TestWith(['previous_value', false, null])]
+    #[TestWith(['previous_value', true, true])]
+    #[TestWith([null, 'real_value', 'real_value'])]
+    #[TestWith([null, true, true])]
+    public function testDeleteIfReturnValue(
+        ?string $previousValue,
+        bool|string $etcdResponse,
+        bool|string|null $expected,
+    ): void
+    {
+        $key = 'test_key';
+
+        $this->client->method('deleteIf')
+            ->with($this->equalTo($key), $this->equalToEtcdValue($previousValue))
+            ->willReturn($etcdResponse);
+
+        $this->assertSame($expected, $this->storage->deleteIf($key, $previousValue, true));
     }
 
     public function testDeleteIfStorageException(): void
@@ -129,7 +169,7 @@ public function testGet(?string $value)
             ->with($this->equalTo($key))
             ->willReturn($value ?? false);
 
-        $this->assertEquals($value, $this->storage->get($key));
+        $this->assertSame($value, $this->storage->get($key));
     }
 
     public function testGStorageException(): void