engine

out := bytes.Buffer{}
errOut := bytes.Buffer{}

eng := setupEngine(&out, &errOut)

ctx := context.TODO()

fn := fnfile.FnDef{
	Name: "test",
	Do: fnfile.Do{
		Steps: fnfile.Steps{
			fnfile.DeferSpec{
				Do: fnfile.Do{
					Steps: fnfile.Steps{
						fnfile.Sh{
							Run: `echo "defer 1: Sub steps of a defer step..."`,
						},
						fnfile.Sh{
							Run: `echo "defer 1: run sequentially"`,
						},
					},
				},
			},
			fnfile.DeferSpec{
				Do: fnfile.Do{
					Steps: fnfile.Steps{
						fnfile.Sh{
							Run: `echo "defer 2: Deferred function calls are executed in Last In First Out order. This should show up first."`,
						},
					},
				},
			},
			fnfile.Sh{
				Run: `echo "Hello, World"`,
			},
		},
	},
}

panicOnError(eng.Run(ctx, fn))

fmt.Print(out.String())

Output:

Hello, World
defer 2: Deferred function calls are executed in Last In First Out order. This should show up first.
defer 1: Sub steps of a defer step...
defer 1: run sequentially

out := bytes.Buffer{}
errOut := bytes.Buffer{}

eng := setupEngine(&out, &errOut)

ctx := context.TODO()

fn := fnfile.FnDef{
	Name: "test",
	Do: fnfile.Do{
		Steps: fnfile.Steps{
			fnfile.Sh{
				Run: `echo "one"`,
			},
			fnfile.Do{
				Steps: fnfile.Steps{
					fnfile.Sh{
						Run: `echo "nested two"`,
					},
				},
			},
			fnfile.Sh{
				Run: `echo "three"`,
			},
		},
	},
}

panicOnError(eng.Run(ctx, fn))

fmt.Println(out.String())

Output:

one
nested two
three

out := bytes.Buffer{}
errOut := bytes.Buffer{}

eng := setupEngine(&out, &errOut)

ctx := context.TODO()

fn := fnfile.FnDef{
	Name: "test",
	Do: fnfile.Do{
		Steps: fnfile.Steps{
			fnfile.Sh{
				Run: `echo "hello"`,
			},
		},
	},
}

panicOnError(eng.Run(ctx, fn))

fmt.Println(out.String())

Output:

hello

out := bytes.Buffer{}
errOut := bytes.Buffer{}

eng := setupEngine(&out, &errOut)

ctx := context.TODO()

fn := fnfile.FnDef{
	Name: "test",
	Do: fnfile.Do{
		Steps: fnfile.Steps{
			fnfile.Sh{
				Run: `echo "first"`,
			},
			fnfile.Sh{
				Run: `false`,
			},
			fnfile.Sh{
				Run: `echo "last"`,
			},
		},
	},
}

err := eng.Run(ctx, fn)

fmt.Printf("result: %s, error: %s", strings.TrimSpace(out.String()), err)

Output:

result: first, error: 1 error occurred:
	* running sh [false]: exit status 1