Implement resumable download queue (T-301)

core/downloader/task_test.go

@@ -0,0 +1,89 @@
+package downloader
+
+import (
+	"errors"
+	"path/filepath"
+	"testing"
+)
+
+func TestTaskValidateAndDerivedPaths(t *testing.T) {
+	task := validTaskForTest()
+	if err := task.Validate(); err != nil {
+		t.Fatalf("Validate() error = %v", err)
+	}
+	paths, err := DeriveTaskPaths(filepath.Join(t.TempDir(), "downloads"), task.RequestID)
+	if err != nil {
+		t.Fatalf("DeriveTaskPaths() error = %v", err)
+	}
+	for _, path := range []string{
+		paths.Metadata,
+		paths.Backup,
+		paths.Part,
+		paths.Completed,
+	} {
+		relative, err := filepath.Rel(paths.Root, path)
+		if err != nil || relative == ".." {
+			t.Fatalf("derived path escapes root: %s", path)
+		}
+	}
+}
+
+func TestTaskRejectsInvalidFields(t *testing.T) {
+	tests := []struct {
+		name   string
+		mutate func(*Task)
+	}{
+		{name: "request id", mutate: func(task *Task) { task.RequestID = "../escape" }},
+		{name: "app id", mutate: func(task *Task) { task.AppID = "Bad App" }},
+		{name: "URL", mutate: func(task *Task) { task.URL = "http://example.invalid/app.zip" }},
+		{name: "state", mutate: func(task *Task) { task.Status = "unknown" }},
+		{name: "negative done", mutate: func(task *Task) { task.Done = -1 }},
+		{name: "done exceeds total", mutate: func(task *Task) { task.Done = task.Total + 1 }},
+		{name: "unknown total value", mutate: func(task *Task) {
+			task.TotalKnown = false
+			task.Total = 10
+		}},
+		{name: "weak etag", mutate: func(task *Task) {
+			task.Validator = EntityValidator{ETag: `W/"weak"`}
+		}},
+		{name: "failed without code", mutate: func(task *Task) {
+			task.Status = StatusFailed
+			task.ErrorCode = ""
+		}},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			task := validTaskForTest()
+			test.mutate(&task)
+			if err := task.Validate(); !errors.Is(err, ErrInvalidTask) {
+				t.Fatalf("Validate() error = %v, want %v", err, ErrInvalidTask)
+			}
+		})
+	}
+}
+
+func TestValidatorsMatchRejectsDifferentKinds(t *testing.T) {
+	expected := EntityValidator{ETag: `"v1"`}
+	if validatorsMatch(expected, EntityValidator{LastModified: "Wed, 16 Jul 2026 10:00:00 GMT"}) {
+		t.Fatal("ETag unexpectedly matched Last-Modified")
+	}
+	if validatorsMatch(expected, EntityValidator{ETag: `"v2"`}) {
+		t.Fatal("different ETags matched")
+	}
+	if !validatorsMatch(expected, EntityValidator{}) {
+		t.Fatal("absent response validator should not contradict If-Range")
+	}
+}
+
+func validTaskForTest() Task {
+	return Task{
+		SchemaVersion: TaskSchemaVersion,
+		RequestID:     "request-001",
+		AppID:         "json-parser",
+		URL:           "https://download.invalid/json-parser.zip",
+		Status:        StatusQueued,
+		TotalKnown:    true,
+		Total:         42,
+		CreatedAt:     "2026-07-16T00:00:00Z",
+	}
+}