fsPromises.readFile ignores encoding option

[Legends]

• Version: v10.0.0-nightly20180309099e621648
• Platform: Win10 x64
• Subsystem: ?

var fs = require('fs/promises'); 
fs.readFile(path,"utf8").then((data)=>...

data will be of type string, when specifying the encoding in the method call, but with the latest version (v10.0.0-nightly20180309099e621648) I have to data.toString("utf8") again, to get the result as string.

By design?

[benjamingr]

Looks like a bug to me, fs.readFileSync returns a string for the same call.

[benjamingr]

Can reproduce locally

> await fsPromises.readFile('v8_build_config.json', 'utf-8')
<Buffer 7b 22 76 38 5f 74 61 72 67 65 74 5f 63 70 75 22 3a 20 22 78 36 34 22 2c 20 22 69 73 5f 63 66 69 22 3a 20 66 61 6c 73 65 2c 20 22 74 61 72 67 65 74 5f ... >
> fs.readFileSync('v8_build_config.json', 'utf-8')
'{"v8_target_cpu": "x64", "is_cfi": false, "target_cpu": "x64", "is_ubsan_vptr": false, "is_gcov_coverage": false, "dcheck_always_on": false, "is_component_build": false, "is_asan": false, "is_debug": false, "v8_enable_i18n_support": true, "is_msan": false, "is_tsan": false, "v8_use_snapshot": true, "v8_enable_verify_predictable": false}'

Note this works correctly when calling util.promisify on fs.readFile

[benjamingr]

Looks like the encoding handling is missing in fs/promises and it is simply ignored https://github.com/nodejs/node/blob/master/lib/fs.js#L403-L405

https://github.com/nodejs/node/blob/master/lib/fs/promises.js#L132 ignores options passed in.

[benjamingr]

Going to tackle this one