diff --git a/src/collections_methods.c b/src/collections_methods.c
index 80c73b7..0667699 100644
--- a/src/collections_methods.c
+++ b/src/collections_methods.c
@@ -864,7 +864,17 @@ PHP_METHOD(Collection, isNotEmpty)
 
 PHP_METHOD(Collection, keys)
 {
-    
+    zend_array* current = COLLECTION_FETCH_EX();
+    ARRAY_NEW_EX(new_collection, current);
+    ZEND_HASH_FOREACH_BUCKET(current, Bucket* bucket)
+        zval val;
+        if (bucket->key)
+            ZVAL_STR(&val, bucket->key);
+        else
+            ZVAL_LONG(&val, bucket->h);
+        zend_hash_next_index_insert(new_collection, &val);
+    ZEND_HASH_FOREACH_END();
+    RETVAL_NEW_COLLECTION(new_collection);
 }
 
 PHP_METHOD(Collection, last)
@@ -925,7 +935,11 @@ PHP_METHOD(Collection, mapValuesTo)
 
 PHP_METHOD(Collection, max)
 {
-    
+    zend_array* current = COLLECTION_FETCH_EX();
+    zval* retval = zend_hash_minmax(current, numeric_compare_function, 1);
+    if (retval)
+        RETURN_ZVAL(retval, 0, 0);
+    RETVAL_NULL();
 }
 
 PHP_METHOD(Collection, maxBy)
@@ -940,7 +954,11 @@ PHP_METHOD(Collection, maxWith)
 
 PHP_METHOD(Collection, min)
 {
-    
+    zend_array* current = COLLECTION_FETCH_EX();
+    zval* retval = zend_hash_minmax(current, numeric_compare_function, 0);
+    if (retval)
+        RETURN_ZVAL(retval, 0, 0);
+    RETVAL_NULL();
 }
 
 PHP_METHOD(Collection, minBy)
@@ -985,7 +1003,19 @@ PHP_METHOD(Collection, minusValuesAssign)
 
 PHP_METHOD(Collection, none)
 {
-    
+    zend_fcall_info fci;
+    zend_fcall_info_cache fcc;
+    ZEND_PARSE_PARAMETERS_START(1, 1)
+        Z_PARAM_FUNC(fci, fcc)
+    ZEND_PARSE_PARAMETERS_END();
+    INIT_FCI();
+    zend_array* current = COLLECTION_FETCH_EX();
+    ZEND_HASH_FOREACH_BUCKET(current, Bucket* bucket)
+        CALLBACK_KEYVAL_INVOKE(params, bucket);
+        if (zend_is_true(&retval))
+            RETURN_FALSE;
+    ZEND_HASH_FOREACH_END();
+    RETURN_TRUE;
 }
 
 PHP_METHOD(Collection, onEach)
@@ -1199,7 +1229,12 @@ PHP_METHOD(Collection, union)
 
 PHP_METHOD(Collection, values)
 {
-    
+    zend_array* current = COLLECTION_FETCH_EX();
+    ARRAY_NEW_EX(new_collection, current);
+    ZEND_HASH_FOREACH_VAL(current, zval* val)
+        zend_hash_next_index_insert(new_collection, val);
+    ZEND_HASH_FOREACH_END();
+    RETVAL_NEW_COLLECTION(new_collection);
 }
 
 PHP_METHOD(Pair, __construct)
diff --git a/stubs/Collection.php b/stubs/Collection.php
index e893bbb..b16d0de 100644
--- a/stubs/Collection.php
+++ b/stubs/Collection.php
@@ -447,7 +447,8 @@ class Collection implements ArrayAccess, Countable
     function mapValuesTo($destination, $transform) {}
 
     /**
-     * Returns the largest element or null if there are no elements.
+     * Returns the largest element or null if there are no elements. The collection should contain
+     * only one type of numeric elements(int/double).
      *
      * @return mixed
      */
@@ -472,7 +473,8 @@ class Collection implements ArrayAccess, Countable
     function maxWith($comparator) {}
 
     /**
-     * Returns the largest element or null if there are no elements.
+     * Returns the largest element or null if there are no elements. The collection should contain
+     * only one type of numeric elements(int/double).
      *
      * @return mixed
      */
diff --git a/tests/004-all-any-none.phpt b/tests/004-all-any-none.phpt
new file mode 100644
index 0000000..e591f2c
--- /dev/null
+++ b/tests/004-all-any-none.phpt
@@ -0,0 +1,31 @@
+--TEST--
+Test Collection::all() and Collection::any().
+--FILE--
+<?php
+$collection = Collection::init(['abc' => 12, 'de' => 5, 'f' => 100]);
+$result = $collection->all(function ($value) {
+    return $value < 100;
+});
+$result1 = $collection->all(function ($value, $key) {
+    return strlen($key) < 4;
+});
+if ($result || !$result1)
+    echo 'Collection::all() failed.', PHP_EOL;
+$result = $collection->any(function ($value) {
+    return $value % 3 == 0;
+});
+$result1 = $collection->any(function ($value, $key) {
+    return strpos($key, 'g') !== false;
+});
+if (!$result || $result1)
+    echo 'Collection::any() failed.', PHP_EOL;
+$result = $collection->none(function ($value) {
+    return $value < 0;
+});
+$result1 = $collection->none(function ($value, $key) {
+    return ctype_alnum($value . $key);
+});
+if (!$result || $result1)
+    echo 'Collection::none() failed.', PHP_EOL;
+?>
+--EXPECT--
diff --git a/tests/004-all-any.phpt b/tests/004-all-any.phpt
deleted file mode 100644
index 6779d24..0000000
--- a/tests/004-all-any.phpt
+++ /dev/null
@@ -1,21 +0,0 @@
---TEST--
-Test Collection::all() and Collection::any().
---FILE--
-<?php
-$collection = Collection::init(['abc' => 12, 'de' => 5, 'f' => 100]);
-$result = $collection->all(function ($value) {
-    return $value < 100;
-});
-$result1 = $collection->all(function ($value, $key) {
-    return strlen($key) < 4;
-});
-$result2 = $collection->any(function ($value) {
-    return $value % 3 == 0;
-});
-$result3 = $collection->any(function ($value, $key) {
-    return strpos($key, 'g') !== false;
-});
-if ($result || !$result1 || !$result2 || $result3)
-    echo 'Collection::all() failed.', PHP_EOL;
-?>
---EXPECT--
diff --git a/tests/023-min-max.phpt b/tests/023-min-max.phpt
new file mode 100644
index 0000000..8c65ccb
--- /dev/null
+++ b/tests/023-min-max.phpt
@@ -0,0 +1,12 @@
+--TEST--
+Test Collection::min() and Collection::max().
+--FILE--
+<?php
+$array = [3.42, 7.15, 0.0, -4.2, 1.64];
+$collection = Collection::init($array);
+if ($collection->max() != max($array) || Collection::init()->max() != null)
+    echo 'Collection::max() failed.', PHP_EOL;
+if ($collection->min() != min($array) || Collection::init()->min() != null)
+    echo 'Collection::min() failed.', PHP_EOL;
+?>
+--EXPECT--
diff --git a/tests/024-keys-values.phpt b/tests/024-keys-values.phpt
new file mode 100644
index 0000000..61881db
--- /dev/null
+++ b/tests/024-keys-values.phpt
@@ -0,0 +1,12 @@
+--TEST--
+Test Collection::none().
+--FILE--
+<?php
+$array = ['a' => 'b', 'c' => ['d'], 10 => 'f'];
+$collection = Collection::init($array);
+if ($collection->keys()->toArray() != array_keys($array))
+    echo 'Collection::keys() failed.', PHP_EOL;
+if ($collection->values()->toArray() != array_values($array))
+    echo 'Collection::values() failed.', PHP_EOL;
+?>
+--EXPECT--