Agent config format 1.18

utils/file_test.go

 // Copyright 2013 Canonical Ltd.
 // Licensed under the AGPLv3, see LICENCE file for details.
 
 package utils_test
 
 import (
+        "fmt"
         "io/ioutil"
+        "os"
         "os/user"
         "path/filepath"
 
         gc "launchpad.net/gocheck"
 
         "launchpad.net/juju-core/juju/osenv"
+        jc "launchpad.net/juju-core/testing/checkers"
         "launchpad.net/juju-core/utils"
 )
 
 type fileSuite struct {
         oldHome string
 }
 
 var _ = gc.Suite(&fileSuite{})
 
 func (s *fileSuite) SetUpTest(c *gc.C) {
@@ skipping 57 matching lines @@
         _, err = f.Write([]byte("hello world"))
         c.Assert(err, gc.IsNil)
         dest := filepath.Join(dir, "dest")
 
         err = utils.CopyFile(dest, f.Name())
         c.Assert(err, gc.IsNil)
         data, err := ioutil.ReadFile(dest)
         c.Assert(err, gc.IsNil)
         c.Assert(string(data), gc.Equals, "hello world")
 }
+
+var atomicWriteFileTests = []struct {
+        summary   string
+        change    func(filename string, contents []byte) error
+        check     func(c *gc.C, fileInfo os.FileInfo)
+        expectErr string
+}{{
+        summary: "atomic file write and chmod 0644",
+        change: func(filename string, contents []byte) error {
+                return utils.AtomicWriteFile(filename, contents, 0765)
+        },
+        check: func(c *gc.C, fi os.FileInfo) {
+                c.Assert(fi.Mode(), gc.Equals, 0765)
+        },
+}, {
+        summary: "atomic file write and change",
+        change: func(filename string, contents []byte) error {
+                chmodChange := func(f *os.File) error {
+                        return f.Chmod(0700)
+                }
+                return utils.AtomicWriteFileAndChange(filename, contents, chmodChange)
+        },
+        check: func(c *gc.C, fi os.FileInfo) {
+                c.Assert(fi.Mode(), gc.Equals, 0700)
+        },
+}, {
+        summary: "atomic file write empty contents",
+        change: func(filename string, contents []byte) error {
+                nopChange := func(*os.File) error {
+                        return nil
+                }
+                return utils.AtomicWriteFileAndChange(filename, contents, nopChange)
+        },
+}, {
+        summary: "atomic file write and failing change func",
+        change: func(filename string, contents []byte) error {
+                errChange := func(*os.File) error {
+                        return fmt.Errorf("pow!")
+                }
+                return utils.AtomicWriteFileAndChange(filename, contents, errChange)
+        },
+        expectErr: "pow!",
+}}
+
+func (*fileSuite) TestAtomicWriteFile(c *gc.C) {
+        dir := c.MkDir()
+        name := "test.file"
+        path := filepath.Join(dir, name)
+        assertDirContents := func(names ...string) {
+                fis, err := ioutil.ReadDir(dir)
+                c.Assert(err, gc.IsNil)
+                c.Assert(fis, gc.HasLen, len(names))
+                for i, name := range names {
+                        c.Assert(fis[i].Name(), gc.Equals, name)
+                }
+        }
+        assertNotExist := func(path string) {
+                _, err := os.Lstat(path)
+                c.Assert(err, jc.Satisfies, os.IsNotExist)
+        }
+
+        for i, test := range atomicWriteFileTests {
+                c.Logf("test %d: %s", i, test.summary)
+                // First - test with file not already there.
+                assertDirContents()
+                assertNotExist(path)
+                contents := []byte("some\ncontents")
+
+                err := test.change(path, contents)
+                if test.expectErr == "" {
+                        c.Assert(err, gc.IsNil)
+                        data, err := ioutil.ReadFile(path)
+                        c.Assert(err, gc.IsNil)
+                        c.Assert(data, jc.DeepEquals, contents)
+                        assertDirContents(name)
+                } else {
+                        c.Assert(err, gc.ErrorMatches, test.expectErr)
+                        assertDirContents()
+                        continue
+                }
+
+                // Second - test with a file already there.
+                contents = []byte("new\ncontents")
+                err = test.change(path, contents)
+                c.Assert(err, gc.IsNil)
+                data, err = ioutil.ReadFile(path)
+                c.Assert(err, gc.IsNil)
+                c.Assert(data, jc.DeepEquals, contents)
+                assertDirContents(name)
+
+                // Remove the file to reset scenario.
+                c.Assert(os.Remove(path), gc.IsNil)
+        }
+}