refactor: extract RunContext Executor in JobExecutor (#984)

This splits the executor from the RunContext into its own function
called newJobExecutor.
We defined an interface called jobInfo which is implemented by the RunContext.
This enables better unit testing because only a small interface needs to
be mocked.

This is a preparation for implementing pre and post actions.

Co-authored-by: Björn Brauer <bjoern.brauer@new-work.se>
Co-authored-by: Marcus Noll <marcus.noll@new-work.se>
Co-authored-by: Jonas Holland <jonas.holland@new-work.se>
Co-authored-by: Robert Kowalski <robert.kowalski@new-work.se>
Co-authored-by: Markus Wolf <markus.wolf@new-work.se>

Co-authored-by: Björn Brauer <bjoern.brauer@new-work.se>
Co-authored-by: Marcus Noll <marcus.noll@new-work.se>
Co-authored-by: Jonas Holland <jonas.holland@new-work.se>
Co-authored-by: Robert Kowalski <robert.kowalski@new-work.se>
Co-authored-by: Markus Wolf <markus.wolf@new-work.se>

act/runner/job_executor.go

@@ -0,0 +1,71 @@
+package runner
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/nektos/act/pkg/common"
+	"github.com/nektos/act/pkg/model"
+)
+
+type jobInfo interface {
+	matrix() map[string]interface{}
+	steps() []*model.Step
+	startContainer() common.Executor
+	stopContainer() common.Executor
+	closeContainer() common.Executor
+	newStepExecutor(step *model.Step) common.Executor
+	interpolateOutputs() common.Executor
+	result(result string)
+}
+
+func newJobExecutor(info jobInfo) common.Executor {
+	steps := make([]common.Executor, 0)
+
+	steps = append(steps, func(ctx context.Context) error {
+		if len(info.matrix()) > 0 {
+			common.Logger(ctx).Infof("\U0001F9EA  Matrix: %v", info.matrix())
+		}
+		return nil
+	})
+
+	steps = append(steps, info.startContainer())
+
+	for i, step := range info.steps() {
+		if step.ID == "" {
+			step.ID = fmt.Sprintf("%d", i)
+		}
+		stepExec := info.newStepExecutor(step)
+		steps = append(steps, func(ctx context.Context) error {
+			err := stepExec(ctx)
+			if err != nil {
+				common.Logger(ctx).Errorf("%v", err)
+				common.SetJobError(ctx, err)
+			} else if ctx.Err() != nil {
+				common.Logger(ctx).Errorf("%v", ctx.Err())
+				common.SetJobError(ctx, ctx.Err())
+			}
+			return nil
+		})
+	}
+	steps = append(steps, func(ctx context.Context) error {
+		err := info.stopContainer()(ctx)
+		if err != nil {
+			return err
+		}
+
+		jobError := common.JobError(ctx)
+		if jobError != nil {
+			info.result("failure")
+		} else {
+			info.result("success")
+		}
+
+		return nil
+	})
+
+	return common.NewPipelineExecutor(steps...).Finally(info.interpolateOutputs()).Finally(func(ctx context.Context) error {
+		info.closeContainer()
+		return nil
+	})
+}