Starts adding speed command to editor

editor/cut_test.go

@@ -9,21 +9,31 @@ import (
 )
 
 var _ = Describe("Cut", func() {
-	Context("with nil cast", func() {
-		It("fails", func() {
-			err := editor.Cut(nil, 1, 2)
-			Expect(err).ToNot(Succeed())
-		})
-	})
-
-	Context("with an empty event stream", func() {
+	Describe("parameter validation", func() {
 		var data = &cast.Cast{
 			EventStream: []*cast.Event{},
 		}
 
-		It("errors", func() {
-			err := editor.Cut(data, 1, 2)
-			Expect(err).ToNot(Succeed())
+		Context("with nil cast", func() {
+			It("fails", func() {
+				err := editor.Cut(nil, 1, 2)
+				Expect(err).ToNot(Succeed())
+			})
+		})
+
+		Context("with an empty event stream", func() {
+
+			It("errors", func() {
+				err := editor.Cut(data, 1, 2)
+				Expect(err).ToNot(Succeed())
+			})
+		})
+
+		Context("with `from` > `to`", func() {
+			It("fails", func() {
+				err := editor.Cut(data, 3, 2)
+				Expect(err).ToNot(Succeed())
+			})
 		})
 	})
 
@@ -65,11 +75,6 @@ var _ = Describe("Cut", func() {
 			initialNumberOfEvents = len(data.EventStream)
 		})
 
-		It("fails if `from` > `to`", func() {
-			err = editor.Cut(data, 3, 2)
-			Expect(err).ToNot(Succeed())
-		})
-
 		Context("cutting a single frame when `from` == `to`", func() {
 			JustBeforeEach(func() {
 				err = editor.Cut(data, 1.2, 1.2)

editor/speed.go

@@ -0,0 +1,33 @@
+package editor
+
+import (
+	"github.com/pkg/errors"
+
+	"github.com/cirocosta/asciinema-edit/cast"
+)
+
+// Speed updates the cast speed by multiplying all of the
+// timestamps in a given range by a given factor.
+func Speed(c *cast.Cast, factor, from, to float64) (err error) {
+	if c == nil {
+		err = errors.Errorf("cast must not be nil")
+		return
+	}
+
+	if len(c.EventStream) == 0 {
+		err = errors.Errorf("event stream must be nonempty")
+		return
+	}
+
+	if factor > 10 || factor < 0.1 {
+		err = errors.Errorf("factor must be within 0.1 and 10 range")
+		return
+	}
+
+	if from >= to {
+		err = errors.Errorf("`from` must not be greater or equal than `to`")
+		return
+	}
+
+	return
+}

editor/speed_test.go

@@ -0,0 +1,120 @@
+package editor_test
+
+import (
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	"github.com/cirocosta/asciinema-edit/cast"
+	"github.com/cirocosta/asciinema-edit/editor"
+)
+
+var _ = Describe("Speed", func() {
+	Describe("parameter validation", func() {
+		var data *cast.Cast
+
+		BeforeEach(func() {
+			data = &cast.Cast{
+				EventStream: []*cast.Event{
+					&cast.Event{},
+				},
+			}
+		})
+
+		Context("with nil cast", func() {
+			It("fails", func() {
+				err := editor.Speed(nil, 1, 2, 3)
+				Expect(err).ToNot(Succeed())
+			})
+		})
+
+		Context("with an empty event stream", func() {
+			var data = &cast.Cast{
+				EventStream: []*cast.Event{},
+			}
+
+			It("errors", func() {
+				err := editor.Speed(data, 1, 1, 2)
+				Expect(err).ToNot(Succeed())
+			})
+		})
+
+		Context("with unusual factors", func() {
+			It("fails with factor > 10", func() {
+				err := editor.Speed(data, 12, 2, 3)
+				Expect(err).ToNot(Succeed())
+
+			})
+
+			It("fails with factor < 0.1", func() {
+				err := editor.Speed(data, 0.05, 2, 3)
+				Expect(err).ToNot(Succeed())
+			})
+		})
+
+		Context("with invalid ranges", func() {
+			It("fails with `from` == `to`", func() {
+				err := editor.Speed(data, 1, 2, 2)
+				Expect(err).ToNot(Succeed())
+			})
+
+			It("fails with `from` > `to`", func() {
+				err := editor.Speed(data, 1, 10, 2)
+				Expect(err).ToNot(Succeed())
+			})
+		})
+	})
+
+	Context("with non-empty event stream", func() {
+		var (
+			data                           *cast.Cast
+			event1, event2, event3, event4 *cast.Event
+			err                            error
+		)
+
+		BeforeEach(func() {
+			event1 = &cast.Event{
+				Time: 1,
+				Data: "event1",
+			}
+			event2 = &cast.Event{
+				Time: 2,
+				Data: "event2",
+			}
+			event3 = &cast.Event{
+				Time: 3,
+				Data: "event3",
+			}
+			event4 = &cast.Event{
+				Time: 4,
+				Data: "event4",
+			}
+
+			data = &cast.Cast{
+				EventStream: []*cast.Event{
+					event1,
+					event2,
+					event3,
+					event4,
+				},
+			}
+		})
+
+		Context("with a slowing down factor and range", func() {
+			JustBeforeEach(func() {
+				err = editor.Speed(data, 2, 1, 2)
+			})
+
+			It("succeeds", func() {
+				Expect(err).To(Succeed())
+			})
+
+			It("properly updates the timestamps", func() {
+				Skip("TODO")
+				Expect(event1.Time).To(Equal(float64(1)))
+				Expect(event2.Time).To(Equal(float64(4)))
+				Expect(event3.Time).To(Equal(float64(5)))
+				Expect(event4.Time).To(Equal(float64(6)))
+			})
+		})
+	})
+})