fix: print version number that updater.writeVersion returns

Closes expo-community/standard-version-expo#18.
Closes expo-community/standard-version-expo#10.

lib/lifecycles/bump.js

@@ -149,15 +149,17 @@ function updateConfigs (args, newVersion) {
 
       if (!stat.isFile()) return
       const contents = fs.readFileSync(configPath, 'utf8')
+      const newContents = updater.updater.writeVersion(contents, newVersion)
+      const realNewVersion = updater.updater.readVersion(newContents)
       checkpoint(
         args,
         'bumping version in ' + updater.filename + ' from %s to %s',
-        [updater.updater.readVersion(contents), newVersion]
+        [updater.updater.readVersion(contents), realNewVersion]
       )
       writeFile(
         args,
         configPath,
-        updater.updater.writeVersion(contents, newVersion)
+        newContents
       )
       // flag any config files that we modify the version # for
       // as having been updated.

package.json

@@ -66,6 +66,7 @@
     "mockery": "^2.1.0",
     "nyc": "^14.1.1",
     "shelljs": "^0.8.4",
-    "std-mocks": "^1.0.1"
+    "std-mocks": "^1.0.1",
+    "strip-ansi": "^6.0.0"
   }
 }

test/core.spec.js

@@ -9,6 +9,7 @@ const { Readable } = require('stream')
 const mockFS = require('mock-fs')
 const mockery = require('mockery')
 const stdMocks = require('std-mocks')
+const stripAnsi = require('strip-ansi')
 
 const cli = require('../command')
 const formatCommitMessage = require('../lib/format-commit-message')
@@ -526,6 +527,37 @@ describe('standard-version', function () {
       })
       fs.readFileSync('VERSION_TRACKER.txt', 'utf-8').should.equal('1.1.0')
     })
+
+    it('displays the new version from custom bumper with --dry-run', async function () {
+      const updater = 'increment-updater.js'
+      const updaterModule = require('./mocks/updater/increment-updater')
+      mock({
+        bump: 'minor',
+        fs: {
+          'increment-version.txt': fs.readFileSync(
+            './test/mocks/increment-version.txt'
+          )
+        }
+      })
+      mockery.registerMock(resolve(process.cwd(), updater), updaterModule)
+
+      const origInfo = console.info
+      const capturedOutput = []
+      console.info = (...args) => {
+        capturedOutput.push(...args)
+        origInfo(...args)
+      }
+      try {
+        await exec({
+          bumpFiles: [{ filename: 'increment-version.txt', updater: 'increment-updater.js' }],
+          dryRun: true
+        })
+        const logOutput = capturedOutput.join(' ')
+        stripAnsi(logOutput).should.include('bumping version in increment-version.txt from 1 to 2')
+      } finally {
+        console.info = origInfo
+      }
+    })
   })
 
   describe('custom `packageFiles` support', function () {

test/mocks/increment-version.txt

@@ -0,0 +1 @@
+1

test/mocks/updater/increment-updater.js

@@ -0,0 +1,7 @@
+module.exports.readVersion = function (contents) {
+  return Number.parseInt(contents)
+}
+
+module.exports.writeVersion = function (contents, version) {
+  return this.readVersion(contents) + 1
+}