fix: call fs.createReadStream lazily

lib/interceptor.js

@@ -198,10 +198,12 @@ module.exports = class Interceptor {
     if (!fs) {
       throw new Error('No fs')
     }
-    const readStream = fs.createReadStream(filePath)
-    readStream.pause()
     this.filePath = filePath
-    return this.reply(statusCode, readStream, headers)
+    return this.reply(statusCode, () =>  {
+      const readStream = fs.createReadStream(filePath)
+      readStream.pause()
+      return readStream
+    }, headers)
   }
 
   // Also match request headers
@@ -453,15 +455,6 @@ module.exports = class Interceptor {
   markConsumed() {
     this.interceptionCounter++
 
-    if (
-      (this.scope.shouldPersist() || this.counter > 0) &&
-      this.interceptionCounter > 1 &&
-      this.filePath
-    ) {
-      this.body = fs.createReadStream(this.filePath)
-      this.body.pause()
-    }
-
     remove(this)
 
     if (!this.scope.shouldPersist() && this.counter < 1) {

tests/got/test_reply_with_file.js

@@ -64,6 +64,29 @@ describe('`replyWithFile()`', () => {
     scope.done()
   })
 
+  it('reply with file with persist', async () => {
+    sinon.spy(fs)
+
+    const scope = nock('http://example.test')
+      .persist()
+      .get('/')
+      .replyWithFile(200, binaryFilePath, {
+        'content-encoding': 'gzip',
+      })
+
+    const response1 = await got('http://example.test/')
+    expect(response1.statusCode).to.equal(200)
+    expect(response1.body).to.have.lengthOf(20)
+
+    const response2 = await got('http://example.test/')
+    expect(response2.statusCode).to.equal(200)
+    expect(response2.body).to.have.lengthOf(20)
+
+    expect(fs.createReadStream.callCount).to.equal(2)
+
+    scope.done()
+  })
+
   describe('with no fs', () => {
     const { Scope } = proxyquire('../../lib/scope', {
       './interceptor': proxyquire('../../lib/interceptor', {
@@ -79,4 +102,16 @@ describe('`replyWithFile()`', () => {
       ).to.throw(Error, 'No fs')
     })
   })
+
+  it('does not create ReadStream eagerly', async () => {
+    sinon.spy(fs)
+
+    nock('http://example.test')
+      .get('/')
+      .replyWithFile(200, binaryFilePath, {
+        'content-encoding': 'gzip',
+      })
+
+    expect(fs.createReadStream.callCount).to.equal(0)
+  })
 })