diff --git a/test/wasm_basic.js b/test/wasm_basic.js
new file mode 100644
index 0000000..57a4d61
--- /dev/null
+++ b/test/wasm_basic.js
@@ -0,0 +1,121 @@
+'use strict';
+
+const expect = require('chai').expect;
+const lib = require('../lib/index.js');
+
+describe('basic', () => {
+
+  it('typeof vcd', done => {
+    expect(lib.wasmparser).to.be.an('function');
+    done();
+  });
+
+  it('typeof vcd instance', done => {
+    expect(lib.wasmparser()).to.be.an('promise');
+    done();
+  });
+
+  it('fail: foo bar', async () => {
+    const inst = await lib.wasmparser();
+    expect(inst.write(Buffer.from(' foo bar ???'))).to.eq(true);
+    expect(inst.info).to.deep.eq({
+      stack: [{}],
+      status: 'declaration',
+      wires: {}
+    });
+  });
+
+  it('$comment', async () => {
+    const inst = await lib.wasmparser();
+    expect(inst.write(Buffer.from(
+      ' \n $comment some text $end $comment more text $end ???'
+    ))).to.eq(true);
+    expect(inst.info).to.deep.eq({
+      stack: [{}],
+      status: 'declaration',
+      wires: {}
+    });
+  });
+
+  it('$version', async () => {
+    const inst = await lib.wasmparser();
+    expect(inst.write(`
+$version Generated by VerilatedVcd $end
+$date Wed Sep 18 22:59:07 2019
+ $end
+$timescale   1ns $end
+
+  $scope   module   top    $end
+    $var wire  1 "}G clock $end
+    $scope module leaf $end
+      $var wire 64 {u counter [63:0] $end
+    $upscope $end
+    $scope module fruit $end
+      $var wire 4 u) point [3:0] $end
+    $upscope $end
+  $upscope $end
+
+  $enddefinitions $end
+`
+)).to.eq(true);
+
+    expect(inst.write(`
+
+#1
+0"}G
+#2
+1"}G
+#300
+0"}G
+b1111000000000000 {u
+#301
+b0000111100000000 {u
+#302
+b0000000011110000 {u
+#303
+b0000000000001111 {u
+`
+)).to.eq(true);
+
+    expect(inst.info).to.deep.eq({
+      status: 'simulation',
+      varId: 'u)',
+      wires: {
+        top: {
+          clock: '"}G',
+          fruit: {
+            point: 'u)'
+          },
+          leaf: {
+            counter: '{u'
+          }
+        }
+      },
+      stack: [{
+        top: {
+          clock: '"}G',
+          fruit: {
+            point: 'u)'
+          },
+          leaf: {
+            counter: '{u'
+          }
+        }
+      },
+      {
+        clock: '"}G',
+        fruit: {
+          point: 'u)'
+        },
+        leaf: {
+          counter: '{u'
+        }
+      },
+      {
+        point: 'u)'
+      }]
+    });
+  });
+});
+
+/* eslint-env mocha */