pana fails checking the screenshots

[Tkko]

Details:
Package: https://pub.dev/packages/pinput
pana version: 0.21.23

Steps to reproduce:

1. Add pinnput_demo.webp to root directory

2. Add screenshots field in pubspec.yaml

screenshots:
  - description: 'This screenshot shows the possible Pinput examples'
    path: pinput_demo.webp

3. Run:
   flutter packages pub global run pana --exit-code-threshold=0 --no-warning --source path ./

Output:

INFO       Running `/Users/dev/fvm/versions/stable/bin/cache/dart-sdk/bin/dart --version`...
INFO       Running `flutter --no-version-check --version --machine`...
INFO       Running `git rev-parse --show-toplevel`...
INFO       Running `flutter --no-version-check pub pub get --no-example`...
INFO       Running `flutter --no-version-check pub pub get --no-example`...
INFO       Running `flutter --no-version-check pub pub outdated --json --up-to-date --no-dev-dependencies --no-dependency-overrides`...
INFO       Analyzing package...
INFO       Running `/Users/dev/fvm/versions/stable/bin/cache/dart-sdk/bin/dart analyze --format machine lib`...
INFO       Running `webpinfo /private/var/folders/zx/9tt6jbqs325_fctz25tn65h80000gn/T/pana_gTPQxo/./pinput_demo.webp`...
'webpinfo' tool not found.INFO       Running `cwebp /private/var/folders/zx/9tt6jbqs325_fctz25tn65h80000gn/T/pana_gTPQxo/./pinput_demo.webp -o /var/folders/zx/9tt6jbqs325_fctz25tn65h80000gn/T/bcj2fn/gen/pinput_demo.webp`...
'cwebp' tool not found.INFO       Running `gif2webp /private/var/folders/zx/9tt6jbqs325_fctz25tn65h80000gn/T/pana_gTPQxo/./pinput_demo.webp -o /var/folders/zx/9tt6jbqs325_fctz25tn65h80000gn/T/bcj2fn/gen/pinput_demo.webp`...
'gif2webp' tool not found.INFO       Running `git init`...
INFO       Running `git remote add origin https://github.com/Tkko/Flutter_PinPut`...
INFO       Running `git remote show origin`...
INFO       Running `git fetch --depth 1 --no-recurse-submodules origin master`...
INFO       Running `git ls-tree -r --name-only --full-tree origin/master`...
INFO       Running `git show origin/master:example/pubspec.yaml`...
INFO       Running `git show origin/master:pubspec.yaml`...
INFO       Running `flutter --no-version-check format --output=none --set-exit-if-changed /private/var/folders/zx/9tt6jbqs325_fctz25tn65h80000gn/T/pana_gTPQxo/./lib`...

## ✗ Follow Dart file conventions (20 / 30)
### [x] 0/10 points: Provide a valid `pubspec.yaml`

<details>
<summary>
Funding URL doesn't exist.
</summary>

At the time of the analysis `https://www.buymeacoffee.com/fman` was unreachable. Make sure that the website is reachable via [`HEAD`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/HEAD) requests.
</details>

### [*] 5/5 points: Provide a valid `README.md`


### [*] 5/5 points: Provide a valid `CHANGELOG.md`


### [*] 10/10 points: Use an OSI-approved license

Detected license: `MIT`.

## ✗ Provide documentation (0 / 10)
### [x] 0/10 points: Package has an example and has no issues with screenshots

Found 4 issues. Showing the first 2:

* `/private/var/folders/zx/9tt6jbqs325_fctz25tn65h80000gn/T/pana_gTPQxo/./pinput_demo.webp`: Tried interpreting screenshot as WebP with `webpinfo "/private/var/folders/zx/9tt6jbqs325_fctz25tn65h80000gn/T/pana_gTPQxo/./pinput_demo.webp"` failed with _exit code_ `2`.
* `/private/var/folders/zx/9tt6jbqs325_fctz25tn65h80000gn/T/pana_gTPQxo/./pinput_demo.webp`: Converting screenshot with `cwebp "/private/var/folders/zx/9tt6jbqs325_fctz25tn65h80000gn/T/pana_gTPQxo/./pinput_demo.webp" -o "/var/folders/zx/9tt6jbqs325_fctz25tn65h80000gn/T/bcj2fn/gen/pinput_demo.webp"` failed with _exit code_ `2`.

## ✓ Platform support (20 / 20)
### [*] 20/20 points: Supports 6 of 6 possible platforms (**iOS**, **Android**, **Web**, **Windows**, **MacOS**, **Linux**)

* ✓ Android
* ✓ iOS
* ✓ Windows
* ✓ Linux
* ✓ MacOS
* ✓ Web

## ✓ Pass static analysis (30 / 30)
### [*] 30/30 points: code has no errors, warnings, lints, or formatting issues


## ✓ Support up-to-date dependencies (20 / 20)
### [*] 10/10 points: All of the package dependencies are supported in the latest version

|Package|Constraint|Compatible|Latest|
|:-|:-|:-|:-|
|[`flutter`]|`flutter`|0.0.0|0.0.0|
|[`smart_auth`]|`^1.0.6`|1.0.6|1.0.6|

<details><summary>Transitive dependencies</summary>

|Package|Constraint|Compatible|Latest|
|:-|:-|:-|:-|
|[`characters`]|-|1.2.1|1.2.1|
|[`collection`]|-|1.16.0|1.17.0|
|[`flutter_web_plugins`]|-|0.0.0|0.0.0|
|[`js`]|-|0.6.4|0.6.6|
|[`material_color_utilities`]|-|0.1.5|0.2.0|
|[`meta`]|-|1.8.0|1.8.0|
|[`sky_engine`]|-|0.0.99|0.0.99|
|[`vector_math`]|-|2.1.2|2.1.4|
</details>

To reproduce run `dart pub outdated --no-dev-dependencies --up-to-date --no-dependency-overrides`.

[`flutter`]: https://pub.dev/packages/flutter
[`smart_auth`]: https://pub.dev/packages/smart_auth
[`characters`]: https://pub.dev/packages/characters
[`collection`]: https://pub.dev/packages/collection
[`flutter_web_plugins`]: https://pub.dev/packages/flutter_web_plugins
[`js`]: https://pub.dev/packages/js
[`material_color_utilities`]: https://pub.dev/packages/material_color_utilities
[`meta`]: https://pub.dev/packages/meta
[`sky_engine`]: https://pub.dev/packages/sky_engine
[`vector_math`]: https://pub.dev/packages/vector_math


### [*] 10/10 points: Package supports latest stable Dart and Flutter SDKs


## ✓ Support sound null safety (20 / 20)
### [*] 20/20 points: Package and dependencies are fully migrated to null safety!


Points: 110/130.

[isoos]

I think you don't have the webp command line tools installed. On Debian/Ubuntu it is done via apt install webp.

[Tkko]

Thanks, that's correct, the message wasn't clear though

[isoos]

@szakarias: can we easily detect if the tools are installed?

[sigurdm]

I think we are detecting this:

pana/lib/src/screenshots.dart

Line 395 in eb444dd

stderr.write("'${cmdAndArgs[0]}' tool not found.");

.
We should probably use writeln instead of write.