fix: allow plotly_static to compile without webdriver feature selected(#402)

When checking out the repository fresh and running `cargo check` at the workspace root, compilation fails because `plotly_static` has no driver features enabled by default.

This PR makes `plotly_static` and `potly` crates compile without a webdriver requirement. However a webdriver needs to be selected to export static plots at runtime.


Signed-off-by: Mridankan Mandal <xerontitan90@gmail.com>
Signed-off-by: Andrei Gherghescu <8067229+andrei-ng@users.noreply.github.com>

---------

Signed-off-by: Mridankan Mandal <xerontitan90@gmail.com>
Signed-off-by: Andrei Gherghescu <8067229+andrei-ng@users.noreply.github.com>
Co-authored-by: RedZapdos123 <redzapdos123@example.com>
Co-authored-by: Andrei Gherghescu <8067229+andrei-ng@users.noreply.github.com>

Author: 3 people

.github/workflows/build.yml

@@ -44,6 +44,8 @@ jobs:
           components: clippy
           targets: wasm32-unknown-unknown
       # lint plotly_static for all features
+      - run: cargo check -p plotly_static
+      - run: cargo test -p plotly_static build_without_driver_feature_returns_error
       - run: cargo clippy -p plotly_static --features geckodriver,webdriver_download -- -D warnings -A deprecated
       - run: cargo clippy -p plotly_static --features chromedriver,webdriver_download -- -D warnings -A deprecated
       # lint the main library workspace for non-wasm target

plotly/Cargo.toml

@@ -88,6 +88,5 @@ image = "0.25"
 itertools = ">=0.10, <0.16"
 itertools-num = "0.1"
 ndarray = "0.17"
-plotly_static = { path = "../plotly_static" }
 rand_distr = "0.6"
 base64 = "0.22"

plotly_static/README.md

@@ -63,6 +63,7 @@ serde_json = "1.0"
 
 ### Feature Flags
 
+- To use static export at runtime, enable exactly one of the driver features below.
 - `chromedriver`: Use Chromedriver and Chrome/Chromium browser for rendering and export
 - `geckodriver`: Use Geckodriver Firefox browser for rendering for rendering and export
 - `webdriver_download`: Auto-download the chosen WebDriver binary

plotly_static/build.rs

@@ -1,3 +1,8 @@
+#![cfg_attr(
+    not(any(feature = "geckodriver", feature = "chromedriver")),
+    allow(unused)
+)]
+
 use std::env;
 use std::fs;
 use std::path::{Path, PathBuf};
@@ -12,10 +17,6 @@ use webdriver_downloader::prelude::*;
 #[cfg(all(feature = "geckodriver", feature = "chromedriver"))]
 compile_error!("Only one of 'geckodriver' or 'chromedriver' features can be enabled at a time.");
 
-// Enforce that at least one driver feature is enabled
-#[cfg(not(any(feature = "geckodriver", feature = "chromedriver")))]
-compile_error!("At least one of 'geckodriver' or 'chromedriver' features must be enabled.");
-
 #[cfg(target_os = "windows")]
 const DRIVER_EXT: &str = ".exe";
 #[cfg(not(target_os = "windows"))]

plotly_static/src/lib.rs

@@ -59,9 +59,10 @@
 //!
 //! ## Features and Dependencies
 //!
-//! ### Required Features
+//! ### Driver Features
 //!
-//! You must enable one of the following features:
+//! For compile time only, no specific feature must be provided. However, to use
+//! static export at runtime, one of the below features must be enabled.
 //!
 //! - `chromedriver`: Use Chrome/Chromium for rendering
 //! - `geckodriver`: Use Firefox for rendering
@@ -294,6 +295,7 @@ use fantoccini::{wd::Capabilities, Client, ClientBuilder};
 #[cfg(not(any(test, feature = "debug")))]
 use log::{debug, error, warn};
 use serde::Serialize;
+#[cfg(any(feature = "chromedriver", feature = "geckodriver"))]
 use serde_json::map::Map as JsonMap;
 use urlencoding::encode;
 use webdriver::WebDriver;
@@ -303,6 +305,9 @@ use crate::template::{image_export_js_script, pdf_export_js_script};
 mod template;
 mod webdriver;
 
+#[cfg(not(any(feature = "chromedriver", feature = "geckodriver")))]
+const DRIVER_FEATURE_REQUIRED: &str = "Static image export at runtime requires enabling either the 'chromedriver' or 'geckodriver' feature.";
+
 /// Supported image formats for static image export.
 ///
 /// This enum defines all the image formats that can be exported from Plotly
@@ -648,6 +653,7 @@ impl StaticExporterBuilder {
     }
 
     /// Create a new WebDriver instance based on the spawn_webdriver flag
+    #[cfg(any(feature = "chromedriver", feature = "geckodriver"))]
     fn create_webdriver(&self) -> Result<WebDriver> {
         let port = self.webdriver_port;
         let in_async = tokio::runtime::Handle::try_current().is_ok();
@@ -688,16 +694,22 @@ impl StaticExporterBuilder {
     ///     .expect("Failed to build AsyncStaticExporter");
     /// ```
     pub fn build_async(&self) -> Result<AsyncStaticExporter> {
-        let wd = self.create_webdriver()?;
-        Ok(AsyncStaticExporter {
-            webdriver_port: self.webdriver_port,
-            webdriver_url: self.webdriver_url.clone(),
-            webdriver: wd,
-            offline_mode: self.offline_mode,
-            pdf_export_timeout: self.pdf_export_timeout,
-            webdriver_browser_caps: self.webdriver_browser_caps.clone(),
-            webdriver_client: None,
-        })
+        #[cfg(not(any(feature = "chromedriver", feature = "geckodriver")))]
+        return Err(anyhow!(DRIVER_FEATURE_REQUIRED));
+
+        #[cfg(any(feature = "chromedriver", feature = "geckodriver"))]
+        {
+            let wd = self.create_webdriver()?;
+            Ok(AsyncStaticExporter {
+                webdriver_port: self.webdriver_port,
+                webdriver_url: self.webdriver_url.clone(),
+                webdriver: wd,
+                offline_mode: self.offline_mode,
+                pdf_export_timeout: self.pdf_export_timeout,
+                webdriver_browser_caps: self.webdriver_browser_caps.clone(),
+                webdriver_client: None,
+            })
+        }
     }
 }
 
@@ -927,6 +939,10 @@ pub struct AsyncStaticExporter {
     pdf_export_timeout: u32,
 
     /// Browser command-line flags (e.g., "--headless", "--no-sandbox")
+    #[cfg_attr(
+        not(any(feature = "chromedriver", feature = "geckodriver")),
+        allow(dead_code)
+    )]
     webdriver_browser_caps: Vec<String>,
 
     /// Cached WebDriver client for session reuse
@@ -1121,46 +1137,53 @@ impl AsyncStaticExporter {
     }
 
     fn build_webdriver_caps(&self) -> Result<Capabilities> {
-        // Define browser capabilities (copied to avoid reordering existing code)
-        let mut caps = JsonMap::new();
-        let mut browser_opts = JsonMap::new();
-        let browser_args = self.webdriver_browser_caps.clone();
-
-        browser_opts.insert("args".to_string(), serde_json::json!(browser_args));
-
-        // Add Chrome binary capability if BROWSER_PATH is set
-        #[cfg(feature = "chromedriver")]
-        if let Ok(chrome_path) = std::env::var("BROWSER_PATH") {
-            browser_opts.insert("binary".to_string(), serde_json::json!(chrome_path));
-            debug!("Added Chrome binary capability: {chrome_path}");
-        }
-        // Add Firefox binary capability if BROWSER_PATH is set
-        #[cfg(feature = "geckodriver")]
-        if let Ok(firefox_path) = std::env::var("BROWSER_PATH") {
-            browser_opts.insert("binary".to_string(), serde_json::json!(firefox_path));
-            debug!("Added Firefox binary capability: {firefox_path}");
-        }
-
-        // Add Firefox-specific preferences for CI environments
-        #[cfg(feature = "geckodriver")]
+        #[cfg(not(any(feature = "chromedriver", feature = "geckodriver")))]
         {
-            let prefs = common::get_firefox_ci_preferences();
-            browser_opts.insert("prefs".to_string(), serde_json::json!(prefs));
-            debug!("Added Firefox preferences for CI compatibility");
+            Err(anyhow!(DRIVER_FEATURE_REQUIRED))
         }
+        #[cfg(any(feature = "chromedriver", feature = "geckodriver"))]
+        {
+            // Define browser capabilities (copied to avoid reordering existing code)
+            let mut caps = JsonMap::new();
+            let mut browser_opts = JsonMap::new();
+            let browser_args = self.webdriver_browser_caps.clone();
+
+            browser_opts.insert("args".to_string(), serde_json::json!(browser_args));
+
+            // Add Chrome binary capability if BROWSER_PATH is set
+            #[cfg(feature = "chromedriver")]
+            if let Ok(chrome_path) = std::env::var("BROWSER_PATH") {
+                browser_opts.insert("binary".to_string(), serde_json::json!(chrome_path));
+                debug!("Added Chrome binary capability: {chrome_path}");
+            }
+            // Add Firefox binary capability if BROWSER_PATH is set
+            #[cfg(feature = "geckodriver")]
+            if let Ok(firefox_path) = std::env::var("BROWSER_PATH") {
+                browser_opts.insert("binary".to_string(), serde_json::json!(firefox_path));
+                debug!("Added Firefox binary capability: {firefox_path}");
+            }
 
-        caps.insert(
-            "browserName".to_string(),
-            serde_json::json!(get_browser_name()),
-        );
-        caps.insert(
-            get_options_key().to_string(),
-            serde_json::json!(browser_opts),
-        );
+            // Add Firefox-specific preferences for CI environments
+            #[cfg(feature = "geckodriver")]
+            {
+                let prefs = common::get_firefox_ci_preferences();
+                browser_opts.insert("prefs".to_string(), serde_json::json!(prefs));
+                debug!("Added Firefox preferences for CI compatibility");
+            }
+
+            caps.insert(
+                "browserName".to_string(),
+                serde_json::json!(get_browser_name()),
+            );
+            caps.insert(
+                get_options_key().to_string(),
+                serde_json::json!(browser_opts),
+            );
 
-        debug!("WebDriver capabilities: {caps:?}");
+            debug!("WebDriver capabilities: {caps:?}");
 
-        Ok(caps)
+            Ok(caps)
+        }
     }
 
     #[cfg(target_os = "windows")]
@@ -1334,6 +1357,15 @@ mod tests {
         let _ = env_logger::try_init();
     }
 
+    #[test]
+    #[cfg(not(any(feature = "chromedriver", feature = "geckodriver")))]
+    fn build_without_driver_feature_returns_error() {
+        match StaticExporterBuilder::default().build_async() {
+            Err(e) => assert_eq!(e.to_string(), DRIVER_FEATURE_REQUIRED),
+            Ok(_) => panic!("expected build to fail without a driver feature"),
+        }
+    }
+
     // Helper to generate unique ports for parallel tests
     #[cfg(not(feature = "debug"))]
     fn get_unique_port() -> u32 {