From 902f0d3ac49ba7e608d5a8b2a55407bbacd1c646 Mon Sep 17 00:00:00 2001
From: Andrey Nering <andrey.nering@gmail.com>
Date: Sat, 9 Feb 2019 10:41:19 -0200
Subject: [PATCH] Don't persist new checksum on the disk if dry mode is enabled

Fixes #166
---
 CHANGELOG.md                       |  5 ++++-
 internal/status/checksum.go        |  9 ++++++---
 status.go                          | 17 +++++++++--------
 task.go                            |  4 ++--
 task_test.go                       | 26 ++++++++++++++++++++++++++
 testdata/dry_checksum/Taskfile.yml |  9 +++++++++
 testdata/dry_checksum/source.txt   |  1 +
 7 files changed, 57 insertions(+), 14 deletions(-)
 create mode 100644 testdata/dry_checksum/Taskfile.yml
 create mode 100644 testdata/dry_checksum/source.txt

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 48542457..059ec4f4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,7 +6,10 @@
   by prefixing it with `:`
   ([#161](https://github.com/go-task/task/issues/161), [#172](https://github.com/go-task/task/issues/172)),
 - Add flag to override the `output` option
-  ([#173](https://github.com/go-task/task/pull/173)).
+  ([#173](https://github.com/go-task/task/pull/173));
+- Fix bug where Task was persisting the new checksum on the disk when the Dry
+  Mode is enabled
+  ([#166](https://github.com/go-task/task/issues/166)).
 
 ## v2.3.0 - 2019-01-02
 
diff --git a/internal/status/checksum.go b/internal/status/checksum.go
index 00798a0c..44331047 100644
--- a/internal/status/checksum.go
+++ b/internal/status/checksum.go
@@ -17,6 +17,7 @@ type Checksum struct {
 	Dir     string
 	Task    string
 	Sources []string
+	Dry     bool
 }
 
 // IsUpToDate implements the Checker interface
@@ -36,9 +37,11 @@ func (c *Checksum) IsUpToDate() (bool, error) {
 		return false, nil
 	}
 
-	_ = os.MkdirAll(filepath.Join(c.Dir, ".task", "checksum"), 0755)
-	if err = ioutil.WriteFile(checksumFile, []byte(newMd5+"\n"), 0644); err != nil {
-		return false, err
+	if !c.Dry {
+		_ = os.MkdirAll(filepath.Join(c.Dir, ".task", "checksum"), 0755)
+		if err = ioutil.WriteFile(checksumFile, []byte(newMd5+"\n"), 0644); err != nil {
+			return false, err
+		}
 	}
 	return oldMd5 == newMd5, nil
 }
diff --git a/status.go b/status.go
index 9bee76a4..173be34b 100644
--- a/status.go
+++ b/status.go
@@ -16,7 +16,7 @@ func (e *Executor) Status(ctx context.Context, calls ...taskfile.Call) error {
 		if err != nil {
 			return err
 		}
-		isUpToDate, err := isTaskUpToDate(ctx, t)
+		isUpToDate, err := e.isTaskUpToDate(ctx, t)
 		if err != nil {
 			return err
 		}
@@ -27,12 +27,12 @@ func (e *Executor) Status(ctx context.Context, calls ...taskfile.Call) error {
 	return nil
 }
 
-func isTaskUpToDate(ctx context.Context, t *taskfile.Task) (bool, error) {
+func (e *Executor) isTaskUpToDate(ctx context.Context, t *taskfile.Task) (bool, error) {
 	if len(t.Status) > 0 {
-		return isTaskUpToDateStatus(ctx, t)
+		return e.isTaskUpToDateStatus(ctx, t)
 	}
 
-	checker, err := getStatusChecker(t)
+	checker, err := e.getStatusChecker(t)
 	if err != nil {
 		return false, err
 	}
@@ -40,15 +40,15 @@ func isTaskUpToDate(ctx context.Context, t *taskfile.Task) (bool, error) {
 	return checker.IsUpToDate()
 }
 
-func statusOnError(t *taskfile.Task) error {
-	checker, err := getStatusChecker(t)
+func (e *Executor) statusOnError(t *taskfile.Task) error {
+	checker, err := e.getStatusChecker(t)
 	if err != nil {
 		return err
 	}
 	return checker.OnError()
 }
 
-func getStatusChecker(t *taskfile.Task) (status.Checker, error) {
+func (e *Executor) getStatusChecker(t *taskfile.Task) (status.Checker, error) {
 	switch t.Method {
 	case "", "timestamp":
 		return &status.Timestamp{
@@ -61,6 +61,7 @@ func getStatusChecker(t *taskfile.Task) (status.Checker, error) {
 			Dir:     t.Dir,
 			Task:    t.Task,
 			Sources: t.Sources,
+			Dry:     e.Dry,
 		}, nil
 	case "none":
 		return status.None{}, nil
@@ -69,7 +70,7 @@ func getStatusChecker(t *taskfile.Task) (status.Checker, error) {
 	}
 }
 
-func isTaskUpToDateStatus(ctx context.Context, t *taskfile.Task) (bool, error) {
+func (e *Executor) isTaskUpToDateStatus(ctx context.Context, t *taskfile.Task) (bool, error) {
 	for _, s := range t.Status {
 		err := execext.RunCommand(ctx, &execext.RunCommandOptions{
 			Command: s,
diff --git a/task.go b/task.go
index 7ea05731..1632d6d6 100644
--- a/task.go
+++ b/task.go
@@ -181,7 +181,7 @@ func (e *Executor) RunTask(ctx context.Context, call taskfile.Call) error {
 	}
 
 	if !e.Force {
-		upToDate, err := isTaskUpToDate(ctx, t)
+		upToDate, err := e.isTaskUpToDate(ctx, t)
 		if err != nil {
 			return err
 		}
@@ -195,7 +195,7 @@ func (e *Executor) RunTask(ctx context.Context, call taskfile.Call) error {
 
 	for i := range t.Cmds {
 		if err := e.runCommand(ctx, t, call, i); err != nil {
-			if err2 := statusOnError(t); err2 != nil {
+			if err2 := e.statusOnError(t); err2 != nil {
 				e.Logger.VerboseErrf("task: error cleaning status on error: %v", err2)
 			}
 
diff --git a/task_test.go b/task_test.go
index e2072865..f3d8ed75 100644
--- a/task_test.go
+++ b/task_test.go
@@ -473,6 +473,32 @@ func TestDry(t *testing.T) {
 	}
 }
 
+// TestDryChecksum tests if the checksum file is not being written to disk
+// if the dry mode is enabled.
+func TestDryChecksum(t *testing.T) {
+	const dir = "testdata/dry_checksum"
+
+	checksumFile := filepath.Join(dir, ".task/checksum/default")
+	_ = os.Remove(checksumFile)
+
+	e := task.Executor{
+		Dir:    dir,
+		Stdout: ioutil.Discard,
+		Stderr: ioutil.Discard,
+		Dry:    true,
+	}
+	assert.NoError(t, e.Setup())
+	assert.NoError(t, e.Run(context.Background(), taskfile.Call{Task: "default"}))
+
+	_, err := os.Stat(checksumFile)
+	assert.Error(t, err, "checksum file should not exist")
+
+	e.Dry = false
+	assert.NoError(t, e.Run(context.Background(), taskfile.Call{Task: "default"}))
+	_, err = os.Stat(checksumFile)
+	assert.NoError(t, err, "checksum file should exist")
+}
+
 func TestIncludes(t *testing.T) {
 	tt := fileContentTest{
 		Dir:       "testdata/includes",
diff --git a/testdata/dry_checksum/Taskfile.yml b/testdata/dry_checksum/Taskfile.yml
new file mode 100644
index 00000000..057816b3
--- /dev/null
+++ b/testdata/dry_checksum/Taskfile.yml
@@ -0,0 +1,9 @@
+version: '2'
+
+tasks:
+  default:
+    cmds:
+      - echo "Working..."
+    sources:
+      - source.txt
+    method: checksum
diff --git a/testdata/dry_checksum/source.txt b/testdata/dry_checksum/source.txt
new file mode 100644
index 00000000..9ed25742
--- /dev/null
+++ b/testdata/dry_checksum/source.txt
@@ -0,0 +1 @@
+Something...