Add snapshot tests

.gitattributes

@@ -1 +1,2 @@
 *.webidl linguist-vendored
+*.snap linguist-generated

crates/cli-support/Cargo.toml

@@ -28,3 +28,6 @@ wasm-bindgen-threads-xform = { path = '../threads-xform', version = '=0.2.92' }
 wasm-bindgen-wasm-conventions = { path = '../wasm-conventions', version = '=0.2.92' }
 wasm-bindgen-wasm-interpreter = { path = "../wasm-interpreter", version = '=0.2.92' }
 unicode-ident = "1.0.5"
+
+[dev-dependencies]
+insta = "1.39.0"

crates/cli-support/tests/common/mod.rs

@@ -0,0 +1,69 @@
+#[macro_export]
+#[allow(unused)]
+macro_rules! test_output_snapshot {
+    ($name:ident, $start_output:literal, $init:expr) => {
+        #[test]
+        fn $name() {
+            use std::path::PathBuf;
+            use wasm_bindgen_cli_support::Bindgen;
+
+            let mut bindgen = Bindgen::new();
+            $init(&mut bindgen);
+            bindgen.input_path(WASM.concat());
+
+            let output = bindgen.generate_output().unwrap();
+            let mut settings = insta::Settings::clone_current();
+            settings.set_snapshot_suffix(
+                PathBuf::from(WASM[1])
+                    .file_stem()
+                    .unwrap()
+                    .to_str()
+                    .unwrap(),
+            );
+            settings.set_prepend_module_to_snapshot(false);
+            if $start_output {
+                settings.bind(|| insta::assert_snapshot!(output.start().unwrap()));
+            } else {
+                settings.bind(|| insta::assert_snapshot!(output.js()));
+            }
+        }
+    };
+}
+#[macro_export]
+#[allow(unused)]
+macro_rules! test_output_empty {
+    ($name:ident, $start_output:literal, $init:expr) => {
+        #[test]
+        fn $name() {
+            use wasm_bindgen_cli_support::Bindgen;
+
+            let mut bindgen = Bindgen::new();
+            $init(&mut bindgen);
+            bindgen.input_path(WASM.concat());
+
+            let output = bindgen.generate_output().unwrap();
+            if $start_output {
+                assert!(output.start().is_none());
+            } else {
+                assert!(output.js().is_empty());
+            }
+        }
+    };
+}
+#[macro_export]
+#[allow(unused)]
+macro_rules! test_output_error {
+    ($name:ident, $init:expr) => {
+        #[test]
+        fn $name() {
+            use wasm_bindgen_cli_support::Bindgen;
+
+            let mut bindgen = Bindgen::new();
+            $init(&mut bindgen);
+            bindgen.input_path(WASM.concat());
+
+            let output = bindgen.generate_output();
+            assert!(output.is_err());
+        }
+    };
+}