Add tests for diff formatters

pkg/components/dashdiffs/formatter_test.go

+package dashdiffs
+
+import (
+	"testing"
+
+	"github.com/grafana/grafana/pkg/components/simplejson"
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func TestDiff(t *testing.T) {
+	// Sample json docs for tests only
+	const (
+		leftJSON = `{
+			"key": "value",
+			"object": {
+				"key": "value",
+				"anotherObject": {
+					"same": "this field is the same in rightJSON",
+					"change": "this field should change in rightJSON",
+					"delete": "this field doesn't appear in rightJSON"
+				}
+			},
+			"array": [
+				"same",
+				"change",
+				"delete"
+			],
+			"embeddedArray": {
+				"array": [
+					"same",
+					"change",
+					"delete"
+				]
+			}
+		}`
+
+		rightJSON = `{
+			"key": "differentValue",
+			"object": {
+				"key": "value",
+				"newKey": "value",
+				"anotherObject": {
+					"same": "this field is the same in rightJSON",
+					"change": "this field should change in rightJSON",
+					"add": "this field is added"
+				}
+			},
+			"array": [
+				"same",
+				"changed!",
+				"add"
+			],
+			"embeddedArray": {
+				"array": [
+					"same",
+					"changed!",
+					"add"
+				]
+			}
+		}`
+	)
+
+	Convey("Testing dashboard diffs", t, func() {
+
+		// Compute the diff between the two JSON objects
+		baseData, err := simplejson.NewJson([]byte(leftJSON))
+		So(err, ShouldBeNil)
+
+		newData, err := simplejson.NewJson([]byte(rightJSON))
+		So(err, ShouldBeNil)
+
+		left, jsonDiff, err := getDiff(baseData, newData)
+		So(err, ShouldBeNil)
+
+		Convey("The JSONFormatter should produce the expected JSON tokens", func() {
+			f := NewJSONFormatter(left)
+			_, err := f.Format(jsonDiff)
+			So(err, ShouldBeNil)
+
+			// Total up the change types. If the number of different change
+			// types is correct, it means that the diff is producing correct
+			// output to the template rendered.
+			changeCounts := make(map[ChangeType]int)
+			for _, line := range f.Lines {
+				changeCounts[line.Change]++
+			}
+
+			// The expectedChangeCounts here were determined by manually
+			// looking at the JSON
+			expectedChangeCounts := map[ChangeType]int{
+				ChangeNil:       12,
+				ChangeAdded:     2,
+				ChangeDeleted:   1,
+				ChangeOld:       5,
+				ChangeNew:       5,
+				ChangeUnchanged: 5,
+			}
+			So(changeCounts, ShouldResemble, expectedChangeCounts)
+		})
+
+		Convey("The BasicFormatter should produce the expected BasicBlocks", func() {
+			f := NewBasicFormatter(left)
+			_, err := f.Format(jsonDiff)
+			So(err, ShouldBeNil)
+
+			bd := &BasicDiff{}
+			blocks := bd.Basic(f.jsonDiff.Lines)
+
+			changeCounts := make(map[ChangeType]int)
+			for _, block := range blocks {
+				for _, change := range block.Changes {
+					changeCounts[change.Change]++
+				}
+
+				for _, summary := range block.Summaries {
+					changeCounts[summary.Change]++
+				}
+
+				changeCounts[block.Change]++
+			}
+
+			expectedChangeCounts := map[ChangeType]int{
+				ChangeNil:     3,
+				ChangeAdded:   2,
+				ChangeDeleted: 1,
+				ChangeOld:     3,
+			}
+			So(changeCounts, ShouldResemble, expectedChangeCounts)
+		})
+	})
+}