feat: tested several situations

__tests__/__snapshots__/arguments-as-string-spec.js.snap

@@ -0,0 +1,23 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`arguments-as-string forms a string from strings and numbers 1`] = `"foo bar 42 the last argument"`;
+
+exports[`arguments-as-string forms string from objects 1`] = `
+"{
+  \\"foo\\": {
+    \\"bar\\": 42
+  }
+} {
+  \\"name\\": \\"Joe\\"
+}"
+`;
+
+exports[`arguments-as-string handles circular references 1`] = `
+"{
+  \\"foo\\": {
+    \\"bar\\": 42
+  }
+} { cannot stringify arg 1, it has type \\"object\\" with keys name, ref }"
+`;
+
+exports[`arguments-as-string handles numbers 1`] = `"1 2 3 4 5 6"`;

__tests__/arguments-as-string-spec.js

@@ -7,4 +7,40 @@ describe('arguments-as-string', () => {
   it('is a function', () => {
     expect(typeof argumentsAsString).toBe('function')
   })
+
+  it('forms a string from strings and numbers', () => {
+    expect(argumentsAsString('foo', 'bar', 42, 'the last argument')).toMatchSnapshot()
+  })
+
+  it('forms string from objects', () => {
+    const o = {
+      foo: {
+        bar: 42
+      }
+    }
+    const p = {
+      name: 'Joe'
+    }
+    const result = argumentsAsString(o, p)
+    expect(result).toMatchSnapshot()
+  })
+
+  it('handles circular references', () => {
+    const o = {
+      foo: {
+        bar: 42
+      }
+    }
+    const p = {
+      name: 'Joe',
+    }
+    p.ref = p
+    const result = argumentsAsString(o, p)
+    expect(result).toMatchSnapshot()
+  })
+
+  it('handles numbers', () => {
+    const result = argumentsAsString(1, 2, 3, 4, 5, 6)
+    expect(result).toMatchSnapshot()
+  })
 })