Test wasm-bindgen feature on CI and fix implementation

.github/workflows/test.yml

@@ -117,7 +117,6 @@ jobs:
         os: [ubuntu-latest]
         target:
           [
-            wasm32-unknown-unknown,
             wasm32-wasi,
             wasm32-unknown-emscripten,
             aarch64-apple-ios,
@@ -130,19 +129,11 @@ jobs:
         with:
           targets: ${{ matrix.target }}
       - uses: Swatinem/rust-cache@v2
-      - uses: actions/setup-node@v3
         with:
           node-version: "12"
-      - run: |
-          set -euxo pipefail
-          export RUST_BACKTRACE=1
-          curl https://rustwasm.github.io/wasm-pack/installer/init.sh -sSf \
-              | bash --noprofile --norc
-          wasm-pack --version
-        shell: bash
       - run: cargo build --target ${{ matrix.target }}  --color=always
 
-  features_check_wasm:
+  test_wasm:
     strategy:
       matrix:
         os: [ubuntu-latest]
@@ -154,10 +145,11 @@ jobs:
           targets: wasm32-unknown-unknown
       - uses: taiki-e/install-action@cargo-hack
       - uses: Swatinem/rust-cache@v2
-      - run: |
-          cargo hack check --feature-powerset --optional-deps serde,rkyv \
-            --skip default --skip __internal_bench --skip __doctest \
-            --skip iana-time-zone --skip pure-rust-locales
+      - uses: actions/setup-node@v3
+      - uses: jetli/wasm-pack-action@v0.4.0
+      # The `TZ` and `NOW` variables are used to compare the results inside the WASM environment
+      # with the host system.
+      - run: TZ="$(date +%z)" NOW="$(date +%s)" wasm-pack test --node -- --features wasmbind
 
   cross-targets:
     strategy:

src/offset/local/mod.rs

@@ -50,15 +50,34 @@ mod inner {
     not(any(target_os = "emscripten", target_os = "wasi"))
 ))]
 mod inner {
-    use crate::{FixedOffset, LocalResult, NaiveDateTime};
+    use crate::{Datelike, FixedOffset, LocalResult, NaiveDateTime, Timelike};
 
-    pub(super) fn offset_from_utc_datetime(_utc: &NaiveDateTime) -> LocalResult<FixedOffset> {
-        let offset = js_sys::Date::new_0().get_timezone_offset();
+    pub(super) fn offset_from_utc_datetime(utc: &NaiveDateTime) -> LocalResult<FixedOffset> {
+        let offset = js_sys::Date::from(utc.and_utc()).get_timezone_offset();
         LocalResult::Single(FixedOffset::west_opt((offset as i32) * 60).unwrap())
     }
 
     pub(super) fn offset_from_local_datetime(local: &NaiveDateTime) -> LocalResult<FixedOffset> {
-        offset_from_utc_datetime(local)
+        let mut year = local.year();
+        if year < 100 {
+            // The API in `js_sys` does not let us create a `Date` with negative years.
+            // And values for years from `0` to `99` map to the years `1900` to `1999`.
+            // Shift the value by a multiple of 400 years until it is `>= 100`.
+            let shift_cycles = (year - 100).div_euclid(400);
+            year -= shift_cycles * 400;
+        }
+        let js_date = js_sys::Date::new_with_year_month_day_hr_min_sec(
+            year as u32,
+            local.month0() as i32,
+            local.day() as i32,
+            local.hour() as i32,
+            local.minute() as i32,
+            local.second() as i32,
+            // ignore milliseconds, our representation of leap seconds may be problematic
+        );
+        let offset = js_date.get_timezone_offset();
+        // We always get a result, even if this time does not exist or is ambiguous.
+        LocalResult::Single(FixedOffset::west_opt((offset as i32) * 60).unwrap())
     }
 }
 
@@ -95,33 +114,9 @@ impl Local {
     }
 
     /// Returns a `DateTime` which corresponds to the current date and time.
-    #[cfg(not(all(
-        target_arch = "wasm32",
-        feature = "wasmbind",
-        not(any(target_os = "emscripten", target_os = "wasi"))
-    )))]
-    #[must_use]
     pub fn now() -> DateTime<Local> {
         Utc::now().with_timezone(&Local)
     }
-
-    /// Returns a `DateTime` which corresponds to the current date and time.
-    #[cfg(all(
-        target_arch = "wasm32",
-        feature = "wasmbind",
-        not(any(target_os = "emscripten", target_os = "wasi"))
-    ))]
-    #[must_use]
-    pub fn now() -> DateTime<Local> {
-        use super::Utc;
-        let now: DateTime<Utc> = super::Utc::now();
-
-        // Workaround missing timezone logic in `time` crate
-        let offset =
-            FixedOffset::west_opt((js_sys::Date::new_0().get_timezone_offset() as i32) * 60)
-                .unwrap();
-        DateTime::from_utc(now.naive_utc(), offset)
-    }
 }
 
 impl TimeZone for Local {

tests/wasm.rs

@@ -1,11 +1,18 @@
+//! Run this test with:
+//! `env TZ="$(date +%z)" NOW="$(date +%s)" wasm-pack test --node -- --features wasmbind`
+//!
+//! The `TZ` and `NOW` variables are used to compare the results inside the WASM environment with
+//! the host system.
+//! The check will fail if the local timezone does not match one of the timezones defined below.
+
 #![cfg(all(
     target_arch = "wasm32",
     feature = "wasmbind",
     not(any(target_os = "emscripten", target_os = "wasi"))
 ))]
 
-use self::chrono::prelude::*;
-use self::wasm_bindgen_test::*;
+use chrono::prelude::*;
+use wasm_bindgen_test::*;
 
 #[wasm_bindgen_test]
 fn now() {
@@ -52,7 +59,7 @@ fn from_is_exact() {
 
     let dt = DateTime::<Utc>::from(now.clone());
 
-    assert_eq!(now.get_time() as i64, dt.timestamp_millis_opt().unwrap());
+    assert_eq!(now.get_time() as i64, dt.timestamp_millis());
 }
 
 #[wasm_bindgen_test]
@@ -72,7 +79,7 @@ fn convert_all_parts_with_milliseconds() {
     let js_date = js_sys::Date::from(time);
 
     assert_eq!(js_date.get_utc_full_year(), 2020);
-    assert_eq!(js_date.get_utc_month(), 12);
+    assert_eq!(js_date.get_utc_month(), 11); // months are numbered 0..=11
     assert_eq!(js_date.get_utc_date(), 1);
     assert_eq!(js_date.get_utc_hours(), 3);
     assert_eq!(js_date.get_utc_minutes(), 1);