Issue #519: Allow includes to be optional

docs/usage.md

@@ -154,6 +154,24 @@ includes:
 > This was a deliberate decision to keep use and implementation simple.
 > If you disagree, open an GitHub issue and explain your use case. =)
 
+### Optional includes
+
+Includes marked as optional will allow Task to continue execution as normal if
+the included file is missing.
+
+```yaml
+version: '3'
+
+includes:
+  tests:
+    taskfile: ./tests/Taskfile.yml
+    optional: true
+tasks:
+  greet:
+    cmds:
+      - echo "This command can still be successfully executed if ./tests/Taskfile.yml does not exist"
+```
+
 ## Task directory
 
 By default, tasks will be executed in the directory where the Taskfile is

task_test.go

@@ -755,6 +755,41 @@ func TestIncludesCallingRoot(t *testing.T) {
 	tt.Run(t)
 }
 
+func TestIncludesOptional(t *testing.T) {
+  tt := fileContentTest{
+    Dir:       "testdata/includes_optional",
+    Target:    "default",
+	  TrimSpace: true,
+	  Files: map[string]string{
+		  "called_dep.txt": "called_dep",
+	  }}
+  tt.Run(t)
+}
+
+func TestIncludesOptionalImplicitFalse(t *testing.T) {
+	e := task.Executor{
+		Dir:    "testdata/includes_optional_implicit_false",
+		Stdout: ioutil.Discard,
+		Stderr: ioutil.Discard,
+	}
+
+	err := e.Setup()
+	assert.Error(t, err)
+	assert.Equal(t, "stat testdata/includes_optional_implicit_false/TaskfileOptional.yml: no such file or directory", err.Error())
+}
+
+func TestIncludesOptionalExplicitFalse(t *testing.T) {
+	e := task.Executor{
+		Dir:    "testdata/includes_optional_explicit_false",
+		Stdout: ioutil.Discard,
+		Stderr: ioutil.Discard,
+	}
+
+	err := e.Setup()
+	assert.Error(t, err)
+	assert.Equal(t, "stat testdata/includes_optional_explicit_false/TaskfileOptional.yml: no such file or directory", err.Error())
+}
+
 func TestSummary(t *testing.T) {
 	const dir = "testdata/summary"
 

taskfile/included_taskfile.go

@@ -10,6 +10,7 @@ import (
 type IncludedTaskfile struct {
 	Taskfile       string
 	Dir            string
+	Optional       bool
 	AdvancedImport bool
 }
 
@@ -92,12 +93,14 @@ func (it *IncludedTaskfile) UnmarshalYAML(unmarshal func(interface{}) error) err
 	var includedTaskfile struct {
 		Taskfile string
 		Dir      string
+		Optional bool
 	}
 	if err := unmarshal(&includedTaskfile); err != nil {
 		return err
 	}
-	it.Dir = includedTaskfile.Dir
 	it.Taskfile = includedTaskfile.Taskfile
+	it.Dir = includedTaskfile.Dir
+	it.Optional = includedTaskfile.Optional
 	it.AdvancedImport = true
 	return nil
 }

taskfile/read/taskfile.go

@@ -42,6 +42,7 @@ func Taskfile(dir string, entrypoint string) (*taskfile.Taskfile, error) {
 			includedTask = taskfile.IncludedTaskfile{
 				Taskfile:       tr.Replace(includedTask.Taskfile),
 				Dir:            tr.Replace(includedTask.Dir),
+				Optional:       includedTask.Optional,
 				AdvancedImport: includedTask.AdvancedImport,
 			}
 			if err := tr.Err(); err != nil {
@@ -56,6 +57,9 @@ func Taskfile(dir string, entrypoint string) (*taskfile.Taskfile, error) {
 		}
 
 		info, err := os.Stat(path)
+		if err != nil && includedTask.Optional {
+			return nil
+		}
 		if err != nil {
 			return err
 		}

testdata/includes_optional/.gitignore

@@ -0,0 +1 @@
+*.txt

testdata/includes_optional/Taskfile.yml

@@ -0,0 +1,11 @@
+version: '3'
+
+includes:
+  included:
+    taskfile: TaskfileOptional.yml
+    optional: true
+
+tasks:
+  default:
+    cmds:
+      - echo "called_dep" > called_dep.txt

testdata/includes_optional_explicit_false/Taskfile.yml

@@ -0,0 +1,11 @@
+version: '3'
+
+includes:
+  included:
+    taskfile: TaskfileOptional.yml
+    optional: false
+
+tasks:
+  default:
+    cmds:
+      - echo "Hello, world!"

testdata/includes_optional_implicit_false/Taskfile.yml

@@ -0,0 +1,9 @@
+version: '3'
+
+includes:
+  included: TaskfileOptional.yml
+
+tasks:
+  default:
+    cmds:
+      - echo "Hello, world!"