fix(symbol): fix toString() and add tests

Author: jedwards1211

src/symbol.spec.ts

@@ -0,0 +1,67 @@
+import * as t from './'
+import { expect } from 'chai'
+import dedent from 'dedent-js'
+
+describe(`t.symbol`, function() {
+  it(`accepts symbols`, function() {
+    t.symbol().assert(Symbol('foo'))
+    t.symbol().assert(Symbol())
+  })
+  it(`rejects everything else`, function() {
+    expect(() => t.symbol().assert(true)).to.throw(
+      t.RuntimeTypeError,
+      dedent`
+        Value must be a symbol
+
+        Expected: symbol
+
+        Actual Value: true
+
+        Actual Type: boolean`
+    )
+    expect(() => t.symbol().assert(2)).to.throw(
+      t.RuntimeTypeError,
+      dedent`
+        Value must be a symbol
+
+        Expected: symbol
+
+        Actual Value: 2
+
+        Actual Type: number`
+    )
+  })
+})
+
+describe(`t.symbol(literal)`, function() {
+  const foo = Symbol('foo')
+  const bar = Symbol()
+  it(`accepts literal value`, function() {
+    t.symbol(foo).assert(foo)
+    t.symbol(bar).assert(bar)
+  })
+  it(`rejects everything else`, function() {
+    expect(() => t.symbol(foo).assert(bar)).to.throw(
+      t.RuntimeTypeError,
+      dedent`
+        Value must be exactly typeof Symbol(foo)
+
+        Expected: typeof Symbol(foo)
+
+        Actual Value: Symbol()
+
+        Actual Type: symbol`
+    )
+    expect(() => t.symbol(foo).assert(3)).to.throw(
+      t.RuntimeTypeError,
+      dedent`
+        Value must be exactly typeof Symbol(foo)
+
+        Expected: typeof Symbol(foo)
+        
+        Actual Value: 3
+        
+        Actual Type: number`
+    )
+  })
+})

src/types/SymbolType.ts

@@ -21,6 +21,6 @@ export default class SymbolType extends Type<symbol> {
   }
 
   toString(): string {
-    return 'Symbol'
+    return 'symbol'
   }
 }