core: Add support for d duration unit (#3323)

* caddy: Add support for `d` duration unit

* Improvements to ParseDuration; add unit tests

Co-authored-by: Matthew Holt <mholt@users.noreply.github.com>

caddy_test.go

@@ -0,0 +1,74 @@
+// Copyright 2015 Matthew Holt and The Caddy Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package caddy
+
+import (
+	"testing"
+	"time"
+)
+
+func TestParseDuration(t *testing.T) {
+	const day = 24 * time.Hour
+	for i, tc := range []struct {
+		input  string
+		expect time.Duration
+	}{
+		{
+			input:  "3h",
+			expect: 3 * time.Hour,
+		},
+		{
+			input:  "1d",
+			expect: day,
+		},
+		{
+			input:  "1d30m",
+			expect: day + 30*time.Minute,
+		},
+		{
+			input:  "1m2d",
+			expect: time.Minute + day*2,
+		},
+		{
+			input:  "1m2d30s",
+			expect: time.Minute + day*2 + 30*time.Second,
+		},
+		{
+			input:  "1d2d",
+			expect: 3 * day,
+		},
+		{
+			input:  "1.5d",
+			expect: time.Duration(1.5 * float64(day)),
+		},
+		{
+			input:  "4m1.25d",
+			expect: 4*time.Minute + time.Duration(1.25*float64(day)),
+		},
+		{
+			input:  "-1.25d12h",
+			expect: time.Duration(-1.25*float64(day)) - 12*time.Hour,
+		},
+	} {
+		actual, err := ParseDuration(tc.input)
+		if err != nil {
+			t.Errorf("Test %d ('%s'): Got error: %v", i, tc.input, err)
+			continue
+		}
+		if actual != tc.expect {
+			t.Errorf("Test %d ('%s'): Expected=%s Actual=%s", i, tc.input, tc.expect, actual)
+		}
+	}
+}