chore: merge probe-engine into probe-cli (#201)

This is how I did it:

1. `git clone https://github.com/ooni/probe-engine internal/engine`

2. ```
(cd internal/engine && git describe --tags)
v0.23.0
```

3. `nvim go.mod` (merging `go.mod` with `internal/engine/go.mod`

4. `rm -rf internal/.git internal/engine/go.{mod,sum}`

5. `git add internal/engine`

6. `find . -type f -name \*.go -exec sed -i 's@/ooni/probe-engine@/ooni/probe-cli/v3/internal/engine@g' {} \;`

7. `go build ./...` (passes)

8. `go test -race ./...` (temporary failure on RiseupVPN)

9. `go mod tidy`

10. this commit message

Once this piece of work is done, we can build a new version of `ooniprobe` that
is using `internal/engine` directly. We need to do more work to ensure all the
other functionality in `probe-engine` (e.g. making mobile packages) are still WAI.

Part of https://github.com/ooni/probe/issues/1335

internal/engine/inputprocessor_test.go

@@ -0,0 +1,166 @@
+package engine
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"github.com/ooni/probe-cli/v3/internal/engine/model"
+)
+
+type FakeInputProcessorExperiment struct {
+	Err error
+	M   []*model.Measurement
+}
+
+func (fipe *FakeInputProcessorExperiment) MeasureWithContext(
+	ctx context.Context, input string) (*model.Measurement, error) {
+	if fipe.Err != nil {
+		return nil, fipe.Err
+	}
+	m := new(model.Measurement)
+	// Here we add annotations to ensure that the input processor
+	// is MERGING annotations as opposed to overwriting them.
+	m.AddAnnotation("antani", "antani")
+	m.AddAnnotation("foo", "baz") // would be bar below
+	m.Input = model.MeasurementTarget(input)
+	fipe.M = append(fipe.M, m)
+	return m, nil
+}
+
+func TestInputProcessorMeasurementFailed(t *testing.T) {
+	expected := errors.New("mocked error")
+	ip := InputProcessor{
+		Experiment: NewInputProcessorExperimentWrapper(
+			&FakeInputProcessorExperiment{Err: expected},
+		),
+		Inputs: []model.URLInfo{{
+			URL: "https://www.kernel.org/",
+		}},
+	}
+	ctx := context.Background()
+	if err := ip.Run(ctx); !errors.Is(err, expected) {
+		t.Fatalf("not the error we expected: %+v", err)
+	}
+}
+
+type FakeInputProcessorSubmitter struct {
+	Err error
+	M   []*model.Measurement
+}
+
+func (fips *FakeInputProcessorSubmitter) Submit(
+	ctx context.Context, m *model.Measurement) error {
+	fips.M = append(fips.M, m)
+	return fips.Err
+}
+
+func TestInputProcessorSubmissionFailed(t *testing.T) {
+	fipe := &FakeInputProcessorExperiment{}
+	expected := errors.New("mocked error")
+	ip := InputProcessor{
+		Annotations: map[string]string{
+			"foo": "bar",
+		},
+		Experiment: NewInputProcessorExperimentWrapper(fipe),
+		Inputs: []model.URLInfo{{
+			URL: "https://www.kernel.org/",
+		}},
+		Options: []string{"fake=true"},
+		Submitter: NewInputProcessorSubmitterWrapper(
+			&FakeInputProcessorSubmitter{Err: expected},
+		),
+	}
+	ctx := context.Background()
+	if err := ip.Run(ctx); !errors.Is(err, expected) {
+		t.Fatalf("not the error we expected: %+v", err)
+	}
+	if len(fipe.M) != 1 {
+		t.Fatal("no measurements generated")
+	}
+	m := fipe.M[0]
+	if m.Input != "https://www.kernel.org/" {
+		t.Fatal("invalid input")
+	}
+	if len(m.Annotations) != 2 {
+		t.Fatal("invalid number of annotations")
+	}
+	if m.Annotations["foo"] != "bar" {
+		t.Fatal("invalid annotation: foo")
+	}
+	if m.Annotations["antani"] != "antani" {
+		t.Fatal("invalid annotation: antani")
+	}
+	if len(m.Options) != 1 || m.Options[0] != "fake=true" {
+		t.Fatal("options not set")
+	}
+}
+
+type FakeInputProcessorSaver struct {
+	Err error
+	M   []*model.Measurement
+}
+
+func (fips *FakeInputProcessorSaver) SaveMeasurement(m *model.Measurement) error {
+	fips.M = append(fips.M, m)
+	return fips.Err
+}
+
+func TestInputProcessorSaveOnDiskFailed(t *testing.T) {
+	expected := errors.New("mocked error")
+	ip := InputProcessor{
+		Experiment: NewInputProcessorExperimentWrapper(
+			&FakeInputProcessorExperiment{},
+		),
+		Inputs: []model.URLInfo{{
+			URL: "https://www.kernel.org/",
+		}},
+		Options: []string{"fake=true"},
+		Saver: NewInputProcessorSaverWrapper(
+			&FakeInputProcessorSaver{Err: expected},
+		),
+		Submitter: NewInputProcessorSubmitterWrapper(
+			&FakeInputProcessorSubmitter{Err: nil},
+		),
+	}
+	ctx := context.Background()
+	if err := ip.Run(ctx); !errors.Is(err, expected) {
+		t.Fatalf("not the error we expected: %+v", err)
+	}
+}
+
+func TestInputProcessorGood(t *testing.T) {
+	fipe := &FakeInputProcessorExperiment{}
+	saver := &FakeInputProcessorSaver{Err: nil}
+	submitter := &FakeInputProcessorSubmitter{Err: nil}
+	ip := InputProcessor{
+		Experiment: NewInputProcessorExperimentWrapper(fipe),
+		Inputs: []model.URLInfo{{
+			URL: "https://www.kernel.org/",
+		}, {
+			URL: "https://www.slashdot.org/",
+		}},
+		Options:   []string{"fake=true"},
+		Saver:     NewInputProcessorSaverWrapper(saver),
+		Submitter: NewInputProcessorSubmitterWrapper(submitter),
+	}
+	ctx := context.Background()
+	if err := ip.Run(ctx); err != nil {
+		t.Fatal(err)
+	}
+	if len(fipe.M) != 2 || len(saver.M) != 2 || len(submitter.M) != 2 {
+		t.Fatal("not all measurements saved")
+	}
+	if submitter.M[0].Input != "https://www.kernel.org/" {
+		t.Fatal("invalid submitter.M[0].Input")
+	}
+	if submitter.M[1].Input != "https://www.slashdot.org/" {
+		t.Fatal("invalid submitter.M[1].Input")
+	}
+	if saver.M[0].Input != "https://www.kernel.org/" {
+		t.Fatal("invalid saver.M[0].Input")
+	}
+	if saver.M[1].Input != "https://www.slashdot.org/" {
+		t.Fatal("invalid saver.M[1].Input")
+	}
+}