Allow shorter syntax for tasks with default configuration

Closes #194
Closes #240

Co-authored-by: Jaedle <dennis.jekubczyk@gmail.com>

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 - Expose `.TASK` variable in templates with the task name
   ([#252](https://github.com/go-task/task/issues/252)).
+- Implement short task syntax
+  ([#194](https://github.com/go-task/task/issues/194), [#240](https://github.com/go-task/task/pull/240)).
 
 # v3.0.0 - Preview 2
 

Taskfile.yml

@@ -72,15 +72,12 @@ tasks:
       - cp ./install-task.sh ./docs/install.sh
 
   ci:
-    cmds:
-      - task: go-get
-        vars: {REPO: golang.org/x/lint/golint}
-      - task: lint
-      - task: test
+    - task: go-get
+      vars: {REPO: golang.org/x/lint/golint}
+    - task: lint
+    - task: test
 
-  go-get:
-    cmds:
-      - go get -u {{.REPO}}
+  go-get: go get -u {{.REPO}}
 
   packages:
     cmds:

docs/usage.md

@@ -840,6 +840,22 @@ $ task default
 
 > The `output` option can also be specified by the `--output` or `-o` flags.
 
+## Short task syntax
+
+Starting on Task v3, you can now write tasks with a shorter syntax if they
+have the default settings (e.g. no custom `env:`, `vars:`, `silent:` , etc):
+
+```yaml
+version: '3'
+
+tasks:
+  build: go build -v -o ./app{{exeExt}} .
+
+  build:
+    - task: build
+    - ./app{{exeExt}} -h localhost -p 8080
+```
+
 ## Watch tasks
 
 If you give a `--watch` or `-w` argument, task will watch for file changes

internal/taskfile/task.go

@@ -1,5 +1,9 @@
 package taskfile
 
+import (
+	"errors"
+)
+
 // Tasks represents a group of tasks
 type Tasks map[string]*Task
 
@@ -20,5 +24,63 @@ type Task struct {
 	Silent        bool
 	Method        string
 	Prefix        string
-	IgnoreError   bool `yaml:"ignore_error"`
+	IgnoreError   bool
+}
+
+var (
+	// ErrCantUnmarshalTask is returned for invalid task YAML
+	ErrCantUnmarshalTask = errors.New("task: can't unmarshal task value")
+)
+
+func (t *Task) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var cmd Cmd
+	if err := unmarshal(&cmd); err == nil && cmd.Cmd != "" {
+		t.Cmds = append(t.Cmds, &cmd)
+		return nil
+	}
+
+	var cmds []*Cmd
+	if err := unmarshal(&cmds); err == nil && len(cmds) > 0 {
+		t.Cmds = cmds
+		return nil
+	}
+
+	var task struct {
+		Cmds          []*Cmd
+		Deps          []*Dep
+		Desc          string
+		Summary       string
+		Sources       []string
+		Generates     []string
+		Status        []string
+		Preconditions []*Precondition
+		Dir           string
+		Vars          Vars
+		Env           Vars
+		Silent        bool
+		Method        string
+		Prefix        string
+		IgnoreError   bool `yaml:"ignore_error"`
+	}
+	if err := unmarshal(&task); err == nil {
+		t.Cmds = task.Cmds
+		t.Deps = task.Deps
+		t.Desc = task.Desc
+		t.Summary = task.Summary
+		t.Sources = task.Sources
+		t.Generates = task.Generates
+		t.Status = task.Status
+		t.Preconditions = task.Preconditions
+		t.Dir = task.Dir
+		t.Vars = task.Vars
+		t.Env = task.Env
+		t.Silent = task.Silent
+		t.Method = task.Method
+		t.Prefix = task.Prefix
+		t.IgnoreError = task.IgnoreError
+
+		return nil
+	}
+
+	return ErrCantUnmarshalTask
 }

task_test.go

@@ -684,3 +684,18 @@ func TestDisplaysErrorOnUnsupportedVersion(t *testing.T) {
 	assert.Equal(t, "task: Taskfile versions prior to v2 are not supported anymore", err.Error())
 
 }
+
+func TestShortTaskNotation(t *testing.T) {
+	const dir = "testdata/short_task_notation"
+
+	var buff bytes.Buffer
+	e := task.Executor{
+		Dir:    dir,
+		Stdout: &buff,
+		Stderr: &buff,
+		Silent: true,
+	}
+	assert.NoError(t, e.Setup())
+	assert.NoError(t, e.Run(context.Background(), taskfile.Call{Task: "default"}))
+	assert.Equal(t, "string-slice-1\nstring-slice-2\nstring\n", buff.String())
+}

testdata/short_task_notation/Taskfile.yml

@@ -0,0 +1,12 @@
+version: '3'
+
+tasks:
+  default:
+    - task: string-slice
+    - task: string
+
+  string-slice:
+    - echo "string-slice-1"
+    - echo "string-slice-2"
+
+  string: echo "string"