Add testing for filepath caching

test/file-utils.spec.ts

@@ -1,6 +1,6 @@
 /* global it, expect, describe */
 
-import { loadFile, templates } from '../src/index'
+import { renderFile, loadFile, templates } from '../src/index'
 import { config } from '../src/config'
 
 var path = require('path'),
@@ -13,3 +13,39 @@ describe('File tests', () => {
     expect(templates.get(filePath)({ name: 'Ben' }, config)).toBeTruthy()
   })
 })
+
+describe('Filepath caching', () => {
+  it('Filepath caching works as expected', async () => {
+    // This test renders templates/has-include.eta with caching enabled, then checks to make sure
+    // `config.filepathCache` contains the expected result afterward
+
+    let viewsDir = path.join(__dirname, 'templates')
+
+    let templateResult = await renderFile('has-include', {}, { views: viewsDir, cache: true })
+
+    expect(templateResult).toEqual(
+      `This is the outermost template. Now we'll include a partial
+
+===========================================================
+This is a partial.
+Hi Test Runner`
+    )
+
+    // The cache is indexed by {filename, path, root, views} (JSON.stringify ignores keys with undefined as their value)
+
+    // Filepath caching is based on the premise that given the same path, includer filename, root directory, and views directory (or directories)
+    // the getPath function will always return the same result (assuming that caching is enabled and we're not expecting the templates to change)
+
+    let pathToHasInclude = `{"filename":"${viewsDir}/has-include.eta","path":"./partial","views":"${viewsDir}"}`
+
+    let pathToPartial = `{"filename":"${viewsDir}/partial.eta","path":"./simple","views":"${viewsDir}"}`
+
+    let pathToSimple = `{"path":"has-include","views":"${viewsDir}"}`
+
+    expect(config.filepathCache).toEqual({
+      [pathToHasInclude]: `${viewsDir}/partial.eta`,
+      [pathToPartial]: `${viewsDir}/simple.eta`,
+      [pathToSimple]: `${viewsDir}/has-include.eta`
+    })
+  })
+})

test/templates/has-include.eta

@@ -0,0 +1,4 @@
+This is the outermost template. Now we'll include a partial
+
+===========================================================
+<%~ includeFile('./partial') %>

test/templates/partial.eta

@@ -0,0 +1,2 @@
+This is a partial.
+<%~ includeFile('./simple', {name: 'Test Runner'}) %>