Move unit tests FormatJsonTest.php to a dedicated file in unit tests
authorAmir Sarabadani <Ladsgroup@gmail.com>
Sun, 7 Jul 2019 22:23:30 +0000 (00:23 +0200)
committerKosta Harlan <kharlan@wikimedia.org>
Mon, 8 Jul 2019 01:35:40 +0000 (21:35 -0400)
Out of 140 tests of this file, 131 one of them are pure unit test
Let's keep the 9 in the original file and move the rest

Bug: T87781
Change-Id: I86dfe17f794c615048b3c20487b0e84d38d13b93

tests/phpunit/includes/json/FormatJsonTest.php
tests/phpunit/unit/includes/json/FormatJsonUnitTest.php [new file with mode: 0644]

index a6adf34..1a99775 100644 (file)
@@ -5,179 +5,6 @@
  */
 class FormatJsonTest extends MediaWikiTestCase {
 
-       public static function provideEncoderPrettyPrinting() {
-               return [
-                       // Four spaces
-                       [ true, '    ' ],
-                       [ '    ', '    ' ],
-                       // Two spaces
-                       [ '  ', '  ' ],
-                       // One tab
-                       [ "\t", "\t" ],
-               ];
-       }
-
-       /**
-        * @dataProvider provideEncoderPrettyPrinting
-        */
-       public function testEncoderPrettyPrinting( $pretty, $expectedIndent ) {
-               $obj = [
-                       'emptyObject' => new stdClass,
-                       'emptyArray' => [],
-                       'string' => 'foobar\\',
-                       'filledArray' => [
-                               [
-                                       123,
-                                       456,
-                               ],
-                               // Nested json works without problems
-                               '"7":["8",{"9":"10"}]',
-                               // Whitespace clean up doesn't touch strings that look alike
-                               "{\n\t\"emptyObject\": {\n\t},\n\t\"emptyArray\": [ ]\n}",
-                       ],
-               ];
-
-               // No trailing whitespace, no trailing linefeed
-               $json = '{
-       "emptyObject": {},
-       "emptyArray": [],
-       "string": "foobar\\\\",
-       "filledArray": [
-               [
-                       123,
-                       456
-               ],
-               "\"7\":[\"8\",{\"9\":\"10\"}]",
-               "{\n\t\"emptyObject\": {\n\t},\n\t\"emptyArray\": [ ]\n}"
-       ]
-}';
-
-               $json = str_replace( "\r", '', $json ); // Windows compat
-               $json = str_replace( "\t", $expectedIndent, $json );
-               $this->assertSame( $json, FormatJson::encode( $obj, $pretty ) );
-       }
-
-       public static function provideEncodeDefault() {
-               return self::getEncodeTestCases( [] );
-       }
-
-       /**
-        * @dataProvider provideEncodeDefault
-        */
-       public function testEncodeDefault( $from, $to ) {
-               $this->assertSame( $to, FormatJson::encode( $from ) );
-       }
-
-       public static function provideEncodeUtf8() {
-               return self::getEncodeTestCases( [ 'unicode' ] );
-       }
-
-       /**
-        * @dataProvider provideEncodeUtf8
-        */
-       public function testEncodeUtf8( $from, $to ) {
-               $this->assertSame( $to, FormatJson::encode( $from, false, FormatJson::UTF8_OK ) );
-       }
-
-       public static function provideEncodeXmlMeta() {
-               return self::getEncodeTestCases( [ 'xmlmeta' ] );
-       }
-
-       /**
-        * @dataProvider provideEncodeXmlMeta
-        */
-       public function testEncodeXmlMeta( $from, $to ) {
-               $this->assertSame( $to, FormatJson::encode( $from, false, FormatJson::XMLMETA_OK ) );
-       }
-
-       public static function provideEncodeAllOk() {
-               return self::getEncodeTestCases( [ 'unicode', 'xmlmeta' ] );
-       }
-
-       /**
-        * @dataProvider provideEncodeAllOk
-        */
-       public function testEncodeAllOk( $from, $to ) {
-               $this->assertSame( $to, FormatJson::encode( $from, false, FormatJson::ALL_OK ) );
-       }
-
-       public function testEncodePhpBug46944() {
-               $this->assertNotEquals(
-                       '\ud840\udc00',
-                       strtolower( FormatJson::encode( "\xf0\xa0\x80\x80" ) ),
-                       'Test encoding an broken json_encode character (U+20000)'
-               );
-       }
-
-       public function testEncodeFail() {
-               // Set up a recursive object that can't be encoded.
-               $a = new stdClass;
-               $b = new stdClass;
-               $a->b = $b;
-               $b->a = $a;
-               $this->assertFalse( FormatJson::encode( $a ) );
-       }
-
-       public function testDecodeReturnType() {
-               $this->assertInternalType(
-                       'object',
-                       FormatJson::decode( '{"Name": "Cheeso", "Rank": 7}' ),
-                       'Default to object'
-               );
-
-               $this->assertInternalType(
-                       'array',
-                       FormatJson::decode( '{"Name": "Cheeso", "Rank": 7}', true ),
-                       'Optional array'
-               );
-       }
-
-       public static function provideParse() {
-               return [
-                       [ null ],
-                       [ true ],
-                       [ false ],
-                       [ 0 ],
-                       [ 1 ],
-                       [ 1.2 ],
-                       [ '' ],
-                       [ 'str' ],
-                       [ [ 0, 1, 2 ] ],
-                       [ [ 'a' => 'b' ] ],
-                       [ [ 'a' => 'b' ] ],
-                       [ [ 'a' => 'b', 'x' => [ 'c' => 'd' ] ] ],
-               ];
-       }
-
-       /**
-        * Recursively convert arrays into stdClass
-        * @param array|string|bool|int|float|null $value
-        * @return stdClass|string|bool|int|float|null
-        */
-       public static function toObject( $value ) {
-               return !is_array( $value ) ? $value : (object)array_map( __METHOD__, $value );
-       }
-
-       /**
-        * @dataProvider provideParse
-        * @param mixed $value
-        */
-       public function testParse( $value ) {
-               $expected = self::toObject( $value );
-               $json = FormatJson::encode( $expected, false, FormatJson::ALL_OK );
-               $this->assertJson( $json );
-
-               $st = FormatJson::parse( $json );
-               $this->assertInstanceOf( Status::class, $st );
-               $this->assertTrue( $st->isGood() );
-               $this->assertEquals( $expected, $st->getValue() );
-
-               $st = FormatJson::parse( $json, FormatJson::FORCE_ASSOC );
-               $this->assertInstanceOf( Status::class, $st );
-               $this->assertTrue( $st->isGood() );
-               $this->assertEquals( $value, $st->getValue() );
-       }
-
        /**
         * Test data for testParseTryFixing.
         *
@@ -252,185 +79,4 @@ class FormatJsonTest extends MediaWikiTestCase {
                }
        }
 
-       public static function provideParseErrors() {
-               return [
-                       [ 'aaa' ],
-                       [ '{"j": 1 ] }' ],
-               ];
-       }
-
-       /**
-        * @dataProvider provideParseErrors
-        * @param mixed $value
-        */
-       public function testParseErrors( $value ) {
-               $st = FormatJson::parse( $value );
-               $this->assertInstanceOf( Status::class, $st );
-               $this->assertFalse( $st->isOK() );
-       }
-
-       public function provideStripComments() {
-               return [
-                       [ '{"a":"b"}', '{"a":"b"}' ],
-                       [ "{\"a\":\"b\"}\n", "{\"a\":\"b\"}\n" ],
-                       [ '/*c*/{"c":"b"}', '{"c":"b"}' ],
-                       [ '{"a":"c"}/*c*/', '{"a":"c"}' ],
-                       [ '/*c//d*/{"c":"b"}', '{"c":"b"}' ],
-                       [ '{/*c*/"c":"b"}', '{"c":"b"}' ],
-                       [ "/*\nc\r\n*/{\"c\":\"b\"}", '{"c":"b"}' ],
-                       [ "//c\n{\"c\":\"b\"}", '{"c":"b"}' ],
-                       [ "//c\r\n{\"c\":\"b\"}", '{"c":"b"}' ],
-                       [ '{"a":"c"}//c', '{"a":"c"}' ],
-                       [ "{\"a-c\"://c\n\"b\"}", '{"a-c":"b"}' ],
-                       [ '{"/*a":"b"}', '{"/*a":"b"}' ],
-                       [ '{"a":"//b"}', '{"a":"//b"}' ],
-                       [ '{"a":"b/*c*/"}', '{"a":"b/*c*/"}' ],
-                       [ "{\"\\\"/*a\":\"b\"}", "{\"\\\"/*a\":\"b\"}" ],
-                       [ '', '' ],
-                       [ '/*c', '' ],
-                       [ '//c', '' ],
-                       [ '"http://example.com"', '"http://example.com"' ],
-                       [ "\0", "\0" ],
-                       [ '"Blåbærsyltetøy"', '"Blåbærsyltetøy"' ],
-               ];
-       }
-
-       /**
-        * @covers FormatJson::stripComments
-        * @dataProvider provideStripComments
-        * @param string $json
-        * @param string $expect
-        */
-       public function testStripComments( $json, $expect ) {
-               $this->assertSame( $expect, FormatJson::stripComments( $json ) );
-       }
-
-       public function provideParseStripComments() {
-               return [
-                       [ '/* blah */true', true ],
-                       [ "// blah \ntrue", true ],
-                       [ '[ "a" , /* blah */ "b" ]', [ 'a', 'b' ] ],
-               ];
-       }
-
-       /**
-        * @covers FormatJson::parse
-        * @covers FormatJson::stripComments
-        * @dataProvider provideParseStripComments
-        * @param string $json
-        * @param mixed $expect
-        */
-       public function testParseStripComments( $json, $expect ) {
-               $st = FormatJson::parse( $json, FormatJson::STRIP_COMMENTS );
-               $this->assertInstanceOf( Status::class, $st );
-               $this->assertTrue( $st->isGood() );
-               $this->assertEquals( $expect, $st->getValue() );
-       }
-
-       /**
-        * Generate a set of test cases for a particular combination of encoder options.
-        *
-        * @param array $unescapedGroups List of character groups to leave unescaped
-        * @return array Arrays of unencoded strings and corresponding encoded strings
-        */
-       private static function getEncodeTestCases( array $unescapedGroups ) {
-               $groups = [
-                       'always' => [
-                               // Forward slash (always unescaped)
-                               '/' => '/',
-
-                               // Control characters
-                               "\0" => '\u0000',
-                               "\x08" => '\b',
-                               "\t" => '\t',
-                               "\n" => '\n',
-                               "\r" => '\r',
-                               "\f" => '\f',
-                               "\x1f" => '\u001f', // representative example
-
-                               // Double quotes
-                               '"' => '\"',
-
-                               // Backslashes
-                               '\\' => '\\\\',
-                               '\\\\' => '\\\\\\\\',
-                               '\\u00e9' => '\\\u00e9', // security check for Unicode unescaping
-
-                               // Line terminators
-                               "\xe2\x80\xa8" => '\u2028',
-                               "\xe2\x80\xa9" => '\u2029',
-                       ],
-                       'unicode' => [
-                               "\xc3\xa9" => '\u00e9',
-                               "\xf0\x9d\x92\x9e" => '\ud835\udc9e', // U+1D49E, outside the BMP
-                       ],
-                       'xmlmeta' => [
-                               '<' => '\u003C', // JSON_HEX_TAG uses uppercase hex digits
-                               '>' => '\u003E',
-                               '&' => '\u0026',
-                       ],
-               ];
-
-               $cases = [];
-               foreach ( $groups as $name => $rules ) {
-                       $leaveUnescaped = in_array( $name, $unescapedGroups );
-                       foreach ( $rules as $from => $to ) {
-                               $cases[] = [ $from, '"' . ( $leaveUnescaped ? $from : $to ) . '"' ];
-                       }
-               }
-
-               return $cases;
-       }
-
-       public function provideEmptyJsonKeyStrings() {
-               return [
-                       [
-                               '{"":"foo"}',
-                               '{"":"foo"}',
-                               ''
-                       ],
-                       [
-                               '{"_empty_":"foo"}',
-                               '{"_empty_":"foo"}',
-                               '_empty_' ],
-                       [
-                               '{"\u005F\u0065\u006D\u0070\u0074\u0079\u005F":"foo"}',
-                               '{"_empty_":"foo"}',
-                               '_empty_'
-                       ],
-                       [
-                               '{"_empty_":"bar","":"foo"}',
-                               '{"_empty_":"bar","":"foo"}',
-                               ''
-                       ],
-                       [
-                               '{"":"bar","_empty_":"foo"}',
-                               '{"":"bar","_empty_":"foo"}',
-                               '_empty_'
-                       ]
-               ];
-       }
-
-       /**
-        * @covers FormatJson::encode
-        * @covers FormatJson::decode
-        * @dataProvider provideEmptyJsonKeyStrings
-        * @param string $json
-        *
-        * Decoding behavior with empty keys can be surprising.
-        * See https://phabricator.wikimedia.org/T206411
-        */
-       public function testEmptyJsonKeyArray( $json, $expect, $php71Name ) {
-               // Decoding to array is consistent across supported PHP versions
-               $this->assertSame( $expect, FormatJson::encode(
-                       FormatJson::decode( $json, true ) ) );
-
-               // Decoding to object differs between supported PHP versions
-               $obj = FormatJson::decode( $json );
-               if ( version_compare( PHP_VERSION, '7.1', '<' ) ) {
-                       $this->assertEquals( 'foo', $obj->_empty_ );
-               } else {
-                       $this->assertEquals( 'foo', $obj->{$php71Name} );
-               }
-       }
 }
diff --git a/tests/phpunit/unit/includes/json/FormatJsonUnitTest.php b/tests/phpunit/unit/includes/json/FormatJsonUnitTest.php
new file mode 100644 (file)
index 0000000..58ad495
--- /dev/null
@@ -0,0 +1,362 @@
+<?php
+
+/**
+ * @covers FormatJson
+ */
+class FormatJsonUnitTest extends MediaWikiUnitTestCase {
+
+       public static function provideEncoderPrettyPrinting() {
+               return [
+                       // Four spaces
+                       [ true, '    ' ],
+                       [ '    ', '    ' ],
+                       // Two spaces
+                       [ '  ', '  ' ],
+                       // One tab
+                       [ "\t", "\t" ],
+               ];
+       }
+
+       /**
+        * @dataProvider provideEncoderPrettyPrinting
+        */
+       public function testEncoderPrettyPrinting( $pretty, $expectedIndent ) {
+               $obj = [
+                       'emptyObject' => new stdClass,
+                       'emptyArray' => [],
+                       'string' => 'foobar\\',
+                       'filledArray' => [
+                               [
+                                       123,
+                                       456,
+                               ],
+                               // Nested json works without problems
+                               '"7":["8",{"9":"10"}]',
+                               // Whitespace clean up doesn't touch strings that look alike
+                               "{\n\t\"emptyObject\": {\n\t},\n\t\"emptyArray\": [ ]\n}",
+                       ],
+               ];
+
+               // No trailing whitespace, no trailing linefeed
+               $json = '{
+       "emptyObject": {},
+       "emptyArray": [],
+       "string": "foobar\\\\",
+       "filledArray": [
+               [
+                       123,
+                       456
+               ],
+               "\"7\":[\"8\",{\"9\":\"10\"}]",
+               "{\n\t\"emptyObject\": {\n\t},\n\t\"emptyArray\": [ ]\n}"
+       ]
+}';
+
+               $json = str_replace( "\r", '', $json ); // Windows compat
+               $json = str_replace( "\t", $expectedIndent, $json );
+               $this->assertSame( $json, FormatJson::encode( $obj, $pretty ) );
+       }
+
+       public static function provideEncodeDefault() {
+               return self::getEncodeTestCases( [] );
+       }
+
+       /**
+        * @dataProvider provideEncodeDefault
+        */
+       public function testEncodeDefault( $from, $to ) {
+               $this->assertSame( $to, FormatJson::encode( $from ) );
+       }
+
+       public static function provideEncodeUtf8() {
+               return self::getEncodeTestCases( [ 'unicode' ] );
+       }
+
+       /**
+        * @dataProvider provideEncodeUtf8
+        */
+       public function testEncodeUtf8( $from, $to ) {
+               $this->assertSame( $to, FormatJson::encode( $from, false, FormatJson::UTF8_OK ) );
+       }
+
+       public static function provideEncodeXmlMeta() {
+               return self::getEncodeTestCases( [ 'xmlmeta' ] );
+       }
+
+       /**
+        * @dataProvider provideEncodeXmlMeta
+        */
+       public function testEncodeXmlMeta( $from, $to ) {
+               $this->assertSame( $to, FormatJson::encode( $from, false, FormatJson::XMLMETA_OK ) );
+       }
+
+       public static function provideEncodeAllOk() {
+               return self::getEncodeTestCases( [ 'unicode', 'xmlmeta' ] );
+       }
+
+       /**
+        * @dataProvider provideEncodeAllOk
+        */
+       public function testEncodeAllOk( $from, $to ) {
+               $this->assertSame( $to, FormatJson::encode( $from, false, FormatJson::ALL_OK ) );
+       }
+
+       public function testEncodePhpBug46944() {
+               $this->assertNotEquals(
+                       '\ud840\udc00',
+                       strtolower( FormatJson::encode( "\xf0\xa0\x80\x80" ) ),
+                       'Test encoding an broken json_encode character (U+20000)'
+               );
+       }
+
+       public function testEncodeFail() {
+               // Set up a recursive object that can't be encoded.
+               $a = new stdClass;
+               $b = new stdClass;
+               $a->b = $b;
+               $b->a = $a;
+               $this->assertFalse( FormatJson::encode( $a ) );
+       }
+
+       public function testDecodeReturnType() {
+               $this->assertInternalType(
+                       'object',
+                       FormatJson::decode( '{"Name": "Cheeso", "Rank": 7}' ),
+                       'Default to object'
+               );
+
+               $this->assertInternalType(
+                       'array',
+                       FormatJson::decode( '{"Name": "Cheeso", "Rank": 7}', true ),
+                       'Optional array'
+               );
+       }
+
+       public static function provideParse() {
+               return [
+                       [ null ],
+                       [ true ],
+                       [ false ],
+                       [ 0 ],
+                       [ 1 ],
+                       [ 1.2 ],
+                       [ '' ],
+                       [ 'str' ],
+                       [ [ 0, 1, 2 ] ],
+                       [ [ 'a' => 'b' ] ],
+                       [ [ 'a' => 'b' ] ],
+                       [ [ 'a' => 'b', 'x' => [ 'c' => 'd' ] ] ],
+               ];
+       }
+
+       /**
+        * Recursively convert arrays into stdClass
+        * @param array|string|bool|int|float|null $value
+        * @return stdClass|string|bool|int|float|null
+        */
+       public static function toObject( $value ) {
+               return !is_array( $value ) ? $value : (object)array_map( __METHOD__, $value );
+       }
+
+       /**
+        * @dataProvider provideParse
+        * @param mixed $value
+        */
+       public function testParse( $value ) {
+               $expected = self::toObject( $value );
+               $json = FormatJson::encode( $expected, false, FormatJson::ALL_OK );
+               $this->assertJson( $json );
+
+               $st = FormatJson::parse( $json );
+               $this->assertInstanceOf( Status::class, $st );
+               $this->assertTrue( $st->isGood() );
+               $this->assertEquals( $expected, $st->getValue() );
+
+               $st = FormatJson::parse( $json, FormatJson::FORCE_ASSOC );
+               $this->assertInstanceOf( Status::class, $st );
+               $this->assertTrue( $st->isGood() );
+               $this->assertEquals( $value, $st->getValue() );
+       }
+
+       public static function provideParseErrors() {
+               return [
+                       [ 'aaa' ],
+                       [ '{"j": 1 ] }' ],
+               ];
+       }
+
+       /**
+        * @dataProvider provideParseErrors
+        * @param mixed $value
+        */
+       public function testParseErrors( $value ) {
+               $st = FormatJson::parse( $value );
+               $this->assertInstanceOf( Status::class, $st );
+               $this->assertFalse( $st->isOK() );
+       }
+
+       public function provideStripComments() {
+               return [
+                       [ '{"a":"b"}', '{"a":"b"}' ],
+                       [ "{\"a\":\"b\"}\n", "{\"a\":\"b\"}\n" ],
+                       [ '/*c*/{"c":"b"}', '{"c":"b"}' ],
+                       [ '{"a":"c"}/*c*/', '{"a":"c"}' ],
+                       [ '/*c//d*/{"c":"b"}', '{"c":"b"}' ],
+                       [ '{/*c*/"c":"b"}', '{"c":"b"}' ],
+                       [ "/*\nc\r\n*/{\"c\":\"b\"}", '{"c":"b"}' ],
+                       [ "//c\n{\"c\":\"b\"}", '{"c":"b"}' ],
+                       [ "//c\r\n{\"c\":\"b\"}", '{"c":"b"}' ],
+                       [ '{"a":"c"}//c', '{"a":"c"}' ],
+                       [ "{\"a-c\"://c\n\"b\"}", '{"a-c":"b"}' ],
+                       [ '{"/*a":"b"}', '{"/*a":"b"}' ],
+                       [ '{"a":"//b"}', '{"a":"//b"}' ],
+                       [ '{"a":"b/*c*/"}', '{"a":"b/*c*/"}' ],
+                       [ "{\"\\\"/*a\":\"b\"}", "{\"\\\"/*a\":\"b\"}" ],
+                       [ '', '' ],
+                       [ '/*c', '' ],
+                       [ '//c', '' ],
+                       [ '"http://example.com"', '"http://example.com"' ],
+                       [ "\0", "\0" ],
+                       [ '"Blåbærsyltetøy"', '"Blåbærsyltetøy"' ],
+               ];
+       }
+
+       /**
+        * @covers FormatJson::stripComments
+        * @dataProvider provideStripComments
+        * @param string $json
+        * @param string $expect
+        */
+       public function testStripComments( $json, $expect ) {
+               $this->assertSame( $expect, FormatJson::stripComments( $json ) );
+       }
+
+       public function provideParseStripComments() {
+               return [
+                       [ '/* blah */true', true ],
+                       [ "// blah \ntrue", true ],
+                       [ '[ "a" , /* blah */ "b" ]', [ 'a', 'b' ] ],
+               ];
+       }
+
+       /**
+        * @covers FormatJson::parse
+        * @covers FormatJson::stripComments
+        * @dataProvider provideParseStripComments
+        * @param string $json
+        * @param mixed $expect
+        */
+       public function testParseStripComments( $json, $expect ) {
+               $st = FormatJson::parse( $json, FormatJson::STRIP_COMMENTS );
+               $this->assertInstanceOf( Status::class, $st );
+               $this->assertTrue( $st->isGood() );
+               $this->assertEquals( $expect, $st->getValue() );
+       }
+
+       /**
+        * Generate a set of test cases for a particular combination of encoder options.
+        *
+        * @param array $unescapedGroups List of character groups to leave unescaped
+        * @return array Arrays of unencoded strings and corresponding encoded strings
+        */
+       private static function getEncodeTestCases( array $unescapedGroups ) {
+               $groups = [
+                       'always' => [
+                               // Forward slash (always unescaped)
+                               '/' => '/',
+
+                               // Control characters
+                               "\0" => '\u0000',
+                               "\x08" => '\b',
+                               "\t" => '\t',
+                               "\n" => '\n',
+                               "\r" => '\r',
+                               "\f" => '\f',
+                               "\x1f" => '\u001f', // representative example
+
+                               // Double quotes
+                               '"' => '\"',
+
+                               // Backslashes
+                               '\\' => '\\\\',
+                               '\\\\' => '\\\\\\\\',
+                               '\\u00e9' => '\\\u00e9', // security check for Unicode unescaping
+
+                               // Line terminators
+                               "\xe2\x80\xa8" => '\u2028',
+                               "\xe2\x80\xa9" => '\u2029',
+                       ],
+                       'unicode' => [
+                               "\xc3\xa9" => '\u00e9',
+                               "\xf0\x9d\x92\x9e" => '\ud835\udc9e', // U+1D49E, outside the BMP
+                       ],
+                       'xmlmeta' => [
+                               '<' => '\u003C', // JSON_HEX_TAG uses uppercase hex digits
+                               '>' => '\u003E',
+                               '&' => '\u0026',
+                       ],
+               ];
+
+               $cases = [];
+               foreach ( $groups as $name => $rules ) {
+                       $leaveUnescaped = in_array( $name, $unescapedGroups );
+                       foreach ( $rules as $from => $to ) {
+                               $cases[] = [ $from, '"' . ( $leaveUnescaped ? $from : $to ) . '"' ];
+                       }
+               }
+
+               return $cases;
+       }
+
+       public function provideEmptyJsonKeyStrings() {
+               return [
+                       [
+                               '{"":"foo"}',
+                               '{"":"foo"}',
+                               ''
+                       ],
+                       [
+                               '{"_empty_":"foo"}',
+                               '{"_empty_":"foo"}',
+                               '_empty_' ],
+                       [
+                               '{"\u005F\u0065\u006D\u0070\u0074\u0079\u005F":"foo"}',
+                               '{"_empty_":"foo"}',
+                               '_empty_'
+                       ],
+                       [
+                               '{"_empty_":"bar","":"foo"}',
+                               '{"_empty_":"bar","":"foo"}',
+                               ''
+                       ],
+                       [
+                               '{"":"bar","_empty_":"foo"}',
+                               '{"":"bar","_empty_":"foo"}',
+                               '_empty_'
+                       ]
+               ];
+       }
+
+       /**
+        * @covers FormatJson::encode
+        * @covers FormatJson::decode
+        * @dataProvider provideEmptyJsonKeyStrings
+        * @param string $json
+        *
+        * Decoding behavior with empty keys can be surprising.
+        * See https://phabricator.wikimedia.org/T206411
+        */
+       public function testEmptyJsonKeyArray( $json, $expect, $php71Name ) {
+               // Decoding to array is consistent across supported PHP versions
+               $this->assertSame( $expect, FormatJson::encode(
+                       FormatJson::decode( $json, true ) ) );
+
+               // Decoding to object differs between supported PHP versions
+               $obj = FormatJson::decode( $json );
+               if ( version_compare( PHP_VERSION, '7.1', '<' ) ) {
+                       $this->assertEquals( 'foo', $obj->_empty_ );
+               } else {
+                       $this->assertEquals( 'foo', $obj->{$php71Name} );
+               }
+       }
+}