test: speed up (#1386)

Reduce redundant fixture setup, Git subprocesses, and large data copies while preserving test coverage.

Local macOS measurements against main:

| Measurement | Before | After |
| --- | ---: | ---: |
| Git package time, median of 3 alternating runs | 4.09 s | 3.48 s (-15%) |
| Allocations across 18 action-bundle cases | 489 MiB | 251 MiB (-49%) |
| Traced Git starts per checkout table run | 234 | 175 |

Reviewed-on: https://gitea.com/gitea/runner/pulls/1386
Reviewed-by: bircni <[email protected]>

act/runner/action_test.go

@@ -249,6 +249,7 @@ func TestActionRunner(t *testing.T) {
 }
 
 func TestGoActionUsesLinuxExecutablePaths(t *testing.T) {
+	actionRoot := t.TempDir()
 	for _, stage := range []string{"main", "pre", "post"} {
 		t.Run(stage, func(t *testing.T) {
 			cm := &containerMock{}
@@ -264,7 +265,7 @@ func TestGoActionUsesLinuxExecutablePaths(t *testing.T) {
 					JobContainer: cm,
 				},
 				action:       &model.Action{Runs: model.ActionRuns{Using: model.ActionRunsUsingGo, Main: "main.go", Pre: "pre.go", Post: "post.go"}},
-				actionDir:    t.TempDir(),
+				actionDir:    filepath.Join(actionRoot, stage),
 				env:          map[string]string{},
 				remoteAction: mustNewRemoteAction(t, "org/repo@ref"),
 			}
@@ -504,11 +505,21 @@ func TestExecAsDockerHoldsCloneLockForRemoteUncached(t *testing.T) {
 }
 
 func TestExecAsDockerImageChecks(t *testing.T) {
+	actionRoot := t.TempDir()
 	originalExists, originalBuild, originalContainer := ContainerImageExistsLocally, ContainerNewDockerBuildExecutor, ContainerNewContainer
 	t.Cleanup(func() {
 		ContainerImageExistsLocally, ContainerNewDockerBuildExecutor, ContainerNewContainer = originalExists, originalBuild, originalContainer
 	})
 	ContainerNewContainer = func(*container.NewContainerInput) container.ExecutionsEnvironment { return fakeContainer{} }
+	var removed bool
+	fakeDockerDaemon(t, func(writer http.ResponseWriter, request *http.Request) {
+		if request.Method == http.MethodDelete {
+			removed = true
+			_, _ = io.WriteString(writer, `[]`)
+		} else {
+			_, _ = io.WriteString(writer, `{"Architecture":"aarch64"}`)
+		}
+	})
 
 	for _, testcase := range []struct {
 		name, platform           string
@@ -529,18 +540,11 @@ func TestExecAsDockerImageChecks(t *testing.T) {
 				checks = append(checks, platform)
 				return testcase.exists && (platform == "any" || testcase.matches), nil
 			}
-			var built, removed bool
+			var built bool
+			removed = false
 			ContainerNewDockerBuildExecutor = func(container.NewDockerBuildExecutorInput) common.Executor {
 				return func(context.Context) error { built = true; return nil }
 			}
-			fakeDockerDaemon(t, func(writer http.ResponseWriter, request *http.Request) {
-				if request.Method == http.MethodDelete {
-					removed = true
-					_, _ = io.WriteString(writer, `[]`)
-				} else {
-					_, _ = io.WriteString(writer, `{"Architecture":"aarch64"}`)
-				}
-			})
 			step := &stepActionRemote{
 				Step: &model.Step{ID: "action"},
 				RunContext: &RunContext{
@@ -555,7 +559,7 @@ func TestExecAsDockerImageChecks(t *testing.T) {
 				action: &model.Action{Runs: model.ActionRuns{Using: "docker", Image: "Dockerfile"}},
 				env:    map[string]string{},
 			}
-			dir := t.TempDir()
+			dir := filepath.Join(actionRoot, testcase.name)
 			require.NoError(t, execAsDocker(t.Context(), step, "action", dir, dir, false, stepStageMain))
 			assert.Equal(t, testcase.wantChecks, checks)
 			assert.Equal(t, testcase.wantBuild, built)
@@ -727,9 +731,9 @@ func TestExecAsDockerStageEntrypoint(t *testing.T) {
 			cm.On("Close").Return(func(context.Context) error { return nil })
 
 			if tc.stage == stepStageMain {
-				require.NoError(t, runActionImpl(step, t.TempDir(), step.remoteAction)(ctx))
+				require.NoError(t, runActionImpl(step, "", step.remoteAction)(ctx))
 			} else {
-				require.NoError(t, execAsDocker(ctx, step, "action", t.TempDir(), t.TempDir(), false, tc.stage))
+				require.NoError(t, execAsDocker(ctx, step, "action", "", "", false, tc.stage))
 			}
 			if tc.warning == "" {
 				assert.Empty(t, hook.AllRecords())