Pull request: 2504 querylog interval

Merge in DNS/adguard-home from 2504-querylog-ivl to master

Updates #2504.

Squashed commit of the following:

commit 5d15a6f735cd195fc81c8af909b56fbc7db1fe21
Merge: 8cd5c30d 97073d0d
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Thu Jul 1 18:45:10 2021 +0300

    Merge branch 'master' into 2504-querylog-ivl

commit 8cd5c30de6f72d4b12162dbc9e3d90132795fe94
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Thu Jul 1 18:35:50 2021 +0300

    client: fix fmt

commit e95d462c31d886bacec0735acc567fec7c962149
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Thu Jul 1 17:58:06 2021 +0300

    home: imp code

commit 48737b249c52a997a4f34dac45fbaf699477b007
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Thu Jul 1 17:23:18 2021 +0300

    home: imp duration

commit 44f5dc3d3ada5120d74caa24cace9a253b8f15d3
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Thu Jul 1 16:55:31 2021 +0300

    home: imp code, docs

commit bb2826521b7e5d248ce2ab686528219c312b8ba2
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Thu Jul 1 16:11:40 2021 +0300

    all: imp code, docs

commit d688aed1f340807a8bac8807c263956b0fc16f5b
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Thu Jul 1 13:49:42 2021 +0300

    all: change querylog interval setting format

internal/home/duration_test.go

@@ -12,6 +12,50 @@ import (
 	yaml "gopkg.in/yaml.v2"
 )
 
+func TestDuration_String(t *testing.T) {
+	testCases := []struct {
+		name string
+		val  time.Duration
+	}{{
+		name: "1s",
+		val:  time.Second,
+	}, {
+		name: "1m",
+		val:  time.Minute,
+	}, {
+		name: "1h",
+		val:  time.Hour,
+	}, {
+		name: "1m1s",
+		val:  time.Minute + time.Second,
+	}, {
+		name: "1h1m",
+		val:  time.Hour + time.Minute,
+	}, {
+		name: "1h0m1s",
+		val:  time.Hour + time.Second,
+	}, {
+		name: "1ms",
+		val:  time.Millisecond,
+	}, {
+		name: "1h0m0.001s",
+		val:  time.Hour + time.Millisecond,
+	}, {
+		name: "1.001s",
+		val:  time.Second + time.Millisecond,
+	}, {
+		name: "1m1.001s",
+		val:  time.Minute + time.Second + time.Millisecond,
+	}}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			d := Duration{Duration: tc.val}
+			assert.Equal(t, tc.name, d.String())
+		})
+	}
+}
+
 // durationEncodingTester is a helper struct to simplify testing different
 // Duration marshalling and unmarshalling cases.
 type durationEncodingTester struct {