Add basic wasm32-unknown-unknown support

.github/workflows/ci.yml

@@ -112,3 +112,43 @@ jobs:
         with:
           command: run
           args: --example default
+
+  wasm-browser-test:
+    name: test wasm support for browser
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        browser:
+          - firefox
+          - chrome
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v2
+
+      - name: Install wasm-pack
+        uses: actions-rs/install@v0.1
+        with:
+          crate: wasm-pack
+          version: latest
+          use-tool-cache: true
+
+      - name: Test on browser
+        run: wasm-pack test --headless --${{ matrix.browser }} -- --no-default-features --test web
+
+  wasm-node-test:
+    name: test wasm support for node
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v2
+
+      - name: Install wasm-pack
+        uses: actions-rs/install@v0.1
+        with:
+          crate: wasm-pack
+          version: latest
+          use-tool-cache: true
+
+      - name: Test on node
+        run: wasm-pack test --node -- --no-default-features --test node

Cargo.toml

@@ -26,6 +26,12 @@ termcolor = { version = "1.0.2", optional = true }
 humantime = { version = "2.0.0", optional = true }
 atty = { version = "0.2.5", optional = true }
 
+[target.wasm32-unknown-unknown.dependencies]
+wasm-bindgen = "^0.2.64"
+
+[target.wasm32-unknown-unknown.dev-dependencies]
+wasm-bindgen-test = "^0.3.19"
+
 [[test]]
 name = "regexp_filter"
 harness = false

src/fmt/writer/mod.rs

@@ -1,5 +1,6 @@
 mod atty;
 mod termcolor;
+mod wasm;
 
 use self::atty::{is_stderr, is_stdout};
 use self::termcolor::BufferWriter;

src/fmt/writer/termcolor/shim_impl.rs

@@ -1,5 +1,7 @@
 use std::io;
 
+#[cfg(all(target_arch = "wasm32", target_vendor = "unknown"))]
+use crate::fmt::writer::wasm;
 use crate::fmt::{Target, WriteStyle};
 
 pub(in crate::fmt::writer) mod glob {}
@@ -33,6 +35,10 @@ impl BufferWriter {
         // This is so their output can be captured by `cargo test`
         let log = String::from_utf8_lossy(&buf.0);
 
+        #[cfg(all(target_arch = "wasm32", target_vendor = "unknown"))]
+        wasm::print(&log, self.target);
+
+        #[cfg(not(all(target_arch = "wasm32", target_vendor = "unknown")))]
         match self.target {
             Target::Stderr => eprint!("{}", log),
             Target::Stdout => print!("{}", log),

src/fmt/writer/wasm.rs

@@ -0,0 +1,37 @@
+//! logging functions from wasm-bindgen.
+//!
+//! Here use the one-param logging functions, all messages should be transformed
+//! to string before passing to the functions. Note that we only need this
+//! module for `wasm32-unknown-unknown` target
+#![cfg(not(feature = "termcolor"))]
+#![cfg(all(target_arch = "wasm32", target_vendor = "unknown"))]
+
+// use log::Level;
+use wasm_bindgen::prelude::*;
+
+use crate::fmt::glob::Target;
+
+pub(in crate::fmt::writer) fn print(msg: &str, t: Target) {
+    // work around for unused variable
+    let _ = t;
+
+    log(&msg);
+}
+
+#[wasm_bindgen]
+extern "C" {
+    #[wasm_bindgen(js_namespace=console)]
+    fn error(text: &str);
+
+    #[wasm_bindgen(js_namespace=console)]
+    fn info(text: &str);
+
+    #[wasm_bindgen(js_namespace=console)]
+    fn warn(text: &str);
+
+    #[wasm_bindgen(js_namespace=console)]
+    fn debug(text: &str);
+
+    #[wasm_bindgen(js_namespace=console)]
+    fn log(text: &str);
+}

tests/node.rs

@@ -0,0 +1,25 @@
+#![cfg(all(target_arch = "wasm32", target_vendor = "unknown"))]
+#![cfg(test)]
+
+use env_logger::Env;
+use log::{debug, error, info, trace, warn};
+
+use wasm_bindgen_test::*;
+
+#[wasm_bindgen_test]
+fn main() {
+    // The `Env` lets us tweak what the environment
+    // variables to read are and what the default
+    // value is if they're missing
+    let env = Env::default()
+        .filter_or("MY_LOG_LEVEL", "trace")
+        .write_style_or("MY_LOG_STYLE", "always");
+
+    env_logger::init_from_env(env);
+
+    trace!("some trace log");
+    debug!("some debug log");
+    info!("some information log");
+    warn!("some warning log");
+    error!("some error log");
+}

tests/web.rs

@@ -0,0 +1,27 @@
+#![cfg(test)]
+#![cfg(all(target_arch = "wasm32", target_vendor = "unknown"))]
+
+use env_logger::Env;
+use log::{debug, error, info, trace, warn};
+
+use wasm_bindgen_test::*;
+
+wasm_bindgen_test_configure!(run_in_browser);
+
+#[wasm_bindgen_test]
+fn main() {
+    // The `Env` lets us tweak what the environment
+    // variables to read are and what the default
+    // value is if they're missing
+    let env = Env::default()
+        .filter_or("MY_LOG_LEVEL", "trace")
+        .write_style_or("MY_LOG_STYLE", "always");
+
+    env_logger::init_from_env(env);
+
+    trace!("some trace log");
+    debug!("some debug log");
+    info!("some information log");
+    warn!("some warning log");
+    error!("some error log");
+}