Apply variable interpolation to a task's examples and its usage. (#57)

Co-authored-by: Jens Petersohn <[email protected]>

interpolation/interpolation.go

@@ -88,6 +88,7 @@ func Tasks(tasks map[string]*task.Task, data map[string]interface{}) error {
 			&task.Summary,
 			&task.Script,
 			&task.Exec,
+			&task.Usage,
 		)
 		if err != nil {
 			return err
@@ -101,6 +102,11 @@ func Tasks(tasks map[string]*task.Task, data map[string]interface{}) error {
 			task.Env[i] = item
 		}
 
+		// interpolate a task's list of examples
+		if err := Examples(task.Examples, data); err != nil {
+			return err
+		}
+
 		// interpolate a task's before and after steps
 		if err := Optionals("before", task.Before, data); err != nil {
 			return err
@@ -112,6 +118,20 @@ func Tasks(tasks map[string]*task.Task, data map[string]interface{}) error {
 	return nil
 }
 
+// Examples interpolates the list of examples (description and command attribute) for a task
+func Examples(examples []*task.Example, data map[string]interface{}) error {
+	for i, example := range examples {
+		if err := interpolate("example-description", data, &example.Description); err != nil {
+			return err
+		}
+		if err := interpolate("example-command", data, &example.Command); err != nil {
+			return err
+		}
+		examples[i] = example
+	}
+	return nil
+}
+
 // Optionals interpolates a list of runnables (i.e. optional steps for a task or the overall robo configuration).
 func Optionals(id string, rs []*task.Runnable, data map[string]interface{}) error {
 	for i, step := range rs {

interpolation/interpolation_test.go

@@ -51,6 +51,10 @@ func TestTasks(t *testing.T) {
 		Script:  "/path/to/{{ .foo }}.sh",
 		Exec:    "{{ .foo }} World!",
 		Env:     []string{"bar={{ .foo }} World!"},
+		Usage:   "robo {{.bar}}",
+		Examples: []*task.Example{
+			{Description: "{{ .foo }} Example!", Command: "robo {{.bar}}"},
+		},
 	}
 
 	vars := map[string]interface{}{"foo": "Hello", "bar": "Bye"}
@@ -68,4 +72,7 @@ func TestTasks(t *testing.T) {
 	assert.Equal(t, "Bye", tk.After[1].Script)
 	assert.Equal(t, "Bye", tk.After[2].Exec)
 	assert.Equal(t, "bar=Hello World!", tk.Env[0])
+	assert.Equal(t, "robo Bye", tk.Usage)
+	assert.Equal(t, "Hello Example!", tk.Examples[0].Description)
+	assert.Equal(t, "robo Bye", tk.Examples[0].Command)
 }