buildstep: keep what one command of an ask writes into the caches for its later commands, so vet, unit tests and the integration compile build each package once; the shared cache stays unchanged (issue 1921, try speed S2)

2026-10-25 00:58:46 +02:00
parent bc16740feb
commit cb548a6a58
3 changed files with 260 additions and 10 deletions
@@ -64,3 +64,39 @@ func TestARunStepReachesNothingAndLeavesTheCachesUnchanged(t *testing.T) {
 		t.Fatalf("the step's write to its workspace did not stay (status %d, %s%s): %q %v", r.Status, r.Stderr, r.Err, b, err)
 	}
 }
+
+// 1921/S2: in one ask (one cache layer), a second go build of the same package does not compile it again, and the
+// shared cache is unchanged afterwards.
+func TestASecondBuildOfTheAskFindsTheFirstsCompiledAndTheSharedCacheIsUnchanged(t *testing.T) {
+	if _, err := exec.LookPath(Bubblewrap); err != nil {
+		t.Fatalf("bubblewrap is not installed here (issue 1309): %v", err)
+	}
+	goBin, err := exec.LookPath("go")
+	if err != nil {
+		t.Fatal(err)
+	}
+	root := t.TempDir()
+	shared := filepath.Join(root, "gobuild")
+	if err := os.MkdirAll(shared, 0o700); err != nil {
+		t.Fatal(err)
+	}
+	workspace := filepath.Join(root, "ws")
+	tree := filepath.Join(workspace, "tree")
+	writeFile(t, tree, "go.mod", "module probe\n\ngo 1.22\n")
+	writeFile(t, tree, "probe.go", "package probe\n\nfunc Probe() int { return 42 }\n")
+	run := Isolated(forgekey.ExecRunnerFor(0), Isolation{Workspace: workspace, Caches: []string{shared},
+		CacheLayer: filepath.Join(workspace, "cachelayer"), ReadOnly: []string{filepath.Dir(filepath.Dir(goBin))}})
+	env := []string{"PATH=" + filepath.Dir(goBin) + ":/usr/bin:/bin", "GOCACHE=" + shared, "GOTOOLCHAIN=local", "GOFLAGS=-mod=mod"}
+	for i, want := range []bool{true, false} {
+		r := run(context.Background(), env, "go", "-C", tree, "build", "-x", "./...")
+		if r.Status != 0 || r.Err != "" {
+			t.Fatalf("build %d: status %d %s\n%s", i+1, r.Status, r.Err, r.Stderr)
+		}
+		if compiled := strings.Contains(r.Stderr, "/compile "); compiled != want {
+			t.Errorf("build %d compiled the package: %v, want %v\n%s", i+1, compiled, want, r.Stderr)
+		}
+	}
+	if entries, _ := os.ReadDir(shared); len(entries) != 0 {
+		t.Errorf("the shared cache was written: %d entries", len(entries))
+	}
+}