Fill entire period when using --fill with periodic filter

When using `klog report --fill` and combining this with a periodic
filter such as `--this-week`, `--last-month`, or `--period`, this PR
fills the entire requested period from begin to end, rather than just
the gaps in between the first and last record.

See #411.

Author: jotaen

klog/app/cli/args/filter.go

@@ -37,7 +37,8 @@ type FilterArgs struct {
 	Tags   []klog.Tag `name:"tag" placeholder:"TAG" group:"Filter Flags:" help:"Entries that match these tags (either in the record summary or the entry summary). You can omit the leading '#'."`
 	Filter string     `name:"filter" placeholder:"EXPR" group:"Filter Flags:" help:"Entries that match this filter expression. Run 'klog info --filtering' to learn how expressions works."`
 
-	hasPartialRecordsWithShouldTotal bool // Field only for internal use
+	hasPartialRecordsWithShouldTotal bool          // Field only for internal use
+	singleShortHandFilter            period.Period // Field only for internal use
 }
 
 func (args *FilterArgs) ApplyFilter(now gotime.Time, rs []klog.Record) ([]klog.Record, app.Error) {
@@ -85,6 +86,9 @@ func (args *FilterArgs) ApplyFilter(now gotime.Time, rs []klog.Record) ([]klog.R
 		}
 		return res
 	}()
+	if len(dateRanges) == 1 {
+		args.singleShortHandFilter = dateRanges[0]
+	}
 	for _, d := range dateRanges {
 		predicates = append(predicates, filter.IsInDateRange{
 			From: d.Since(),
@@ -134,3 +138,9 @@ func (args *FilterArgs) ApplyFilter(now gotime.Time, rs []klog.Record) ([]klog.R
 	}
 	return rs, nil
 }
+
+// SinglePeriodRequested returns the corresponding period if a single short-hand
+// filter (such as --this-month or --last-week) was used.
+func (args *FilterArgs) SinglePeriodRequested() period.Period {
+	return args.singleShortHandFilter
+}

klog/app/cli/report.go

@@ -65,7 +65,12 @@ func (opt *Report) Run(ctx app.Context) app.Error {
 	aggregator := opt.aggregator()
 	recordGroups, dates := groupByDate(aggregator.DateHash, records)
 	if opt.Fill {
-		dates = allDatesRange(records[0].Date(), records[len(records)-1].Date())
+		singlePeriod := opt.FilterArgs.SinglePeriodRequested()
+		if singlePeriod != nil {
+			dates = allDatesRange(singlePeriod.Since(), singlePeriod.Until())
+		} else {
+			dates = allDatesRange(records[0].Date(), records[len(records)-1].Date())
+		}
 	}
 
 	// Table setup

klog/app/cli/report_test.go

@@ -282,6 +282,29 @@ func TestYearReport(t *testing.T) {
 `, state.printBuffer)
 }
 
+func TestPeriodicalReportWithFill(t *testing.T) {
+	state, err := NewTestingContext()._SetNow(2018, 8, 24, 0, 0)._SetRecords(`
+2018-04-02 (8h!)
+	8h
+
+2018-08-10 (5h30m!)
+	2h
+
+2018-08-23 (2h!)
+	5h20m
+`)._Run((&Report{AggregateBy: "quarter", DiffArgs: args.DiffArgs{Diff: true}, Fill: true, FilterArgs: args.FilterArgs{ThisYear: true}}).Run)
+	require.Nil(t, err)
+	assert.Equal(t, `
+           Total    Should     Diff
+2018 Q1                            
+     Q2       8h       8h!       0m
+     Q3    7h20m    7h30m!     -10m
+     Q4                            
+        ======== ========= ========
+          15h20m   15h30m!     -10m
+`, state.printBuffer)
+}
+
 func TestReportWithChart(t *testing.T) {
 	t.Run("Daily (default) aggregation", func(t *testing.T) {
 		state, err := NewTestingContext()._SetRecords(`