Add a test for building a wasm crate in a workspace

Fixes rustwasm#252

tests/all/build.rs

@@ -34,3 +34,51 @@ fn it_should_build_js_hello_world_example() {
     .unwrap();
     fixture.run(cli.cmd).unwrap();
 }
+
+#[test]
+fn it_should_build_crates_in_a_workspace() {
+    let fixture = utils::fixture::Fixture::new();
+    fixture
+        .file(
+            "Cargo.toml",
+            r#"
+                [workspace]
+                members = ["./blah"]
+            "#,
+        )
+        .file(
+            "blah/Cargo.toml",
+            r#"
+                [package]
+                authors = ["The wasm-pack developers"]
+                description = "so awesome rust+wasm package"
+                license = "WTFPL"
+                name = "blah"
+                repository = "https://github.com/rustwasm/wasm-pack.git"
+                version = "0.1.0"
+
+                [lib]
+                crate-type = ["cdylib"]
+
+                [dependencies]
+                wasm-bindgen = "=0.2.21"
+            "#,
+        )
+        .file(
+            "blah/src/lib.rs",
+            r#"
+                extern crate wasm_bindgen;
+                use wasm_bindgen::prelude::*;
+
+                #[wasm_bindgen]
+                pub fn hello() -> u32 { 42 }
+            "#,
+        );
+    fixture.install_local_wasm_bindgen();
+    let cli = Cli::from_iter_safe(vec![
+        "wasm-pack",
+        "build",
+        &fixture.path.join("blah").display().to_string(),
+    ]).unwrap();
+    fixture.run(cli.cmd).unwrap();
+}