Add LocalTime.FromHoursSinceMidnight and FromMinutesSinceMidnight

Fixes #1366

(FromHoursSinceMidnight is a little less useful, but I've included it for consistency/completeness.)

src/NodaTime.Test/LocalTimeTest.Construction.cs

@@ -157,5 +157,33 @@ public void FromSecondsSinceMidnight_RangeChecks()
             Assert.Throws<ArgumentOutOfRangeException>(() => LocalTime.FromSecondsSinceMidnight(-1));
             Assert.Throws<ArgumentOutOfRangeException>(() => LocalTime.FromSecondsSinceMidnight(NodaConstants.SecondsPerDay));
         }
+
+        [Test]
+        public void FromMinutesSinceMidnight_Valid()
+        {
+            Assert.AreEqual(LocalTime.Midnight, LocalTime.FromMinutesSinceMidnight(0));
+            Assert.AreEqual(LocalTime.Midnight - Period.FromMinutes(1), LocalTime.FromMinutesSinceMidnight(NodaConstants.MinutesPerDay - 1));
+        }
+
+        [Test]
+        public void FromMinutesSinceMidnight_RangeChecks()
+        {
+            Assert.Throws<ArgumentOutOfRangeException>(() => LocalTime.FromMinutesSinceMidnight(-1));
+            Assert.Throws<ArgumentOutOfRangeException>(() => LocalTime.FromMinutesSinceMidnight(NodaConstants.MinutesPerDay));
+        }
+
+        [Test]
+        public void FromHoursSinceMidnight_Valid()
+        {
+            Assert.AreEqual(LocalTime.Midnight, LocalTime.FromHoursSinceMidnight(0));
+            Assert.AreEqual(LocalTime.Midnight - Period.FromHours(1), LocalTime.FromHoursSinceMidnight(NodaConstants.HoursPerDay - 1));
+        }
+
+        [Test]
+        public void FromHoursSinceMidnight_RangeChecks()
+        {
+            Assert.Throws<ArgumentOutOfRangeException>(() => LocalTime.FromHoursSinceMidnight(-1));
+            Assert.Throws<ArgumentOutOfRangeException>(() => LocalTime.FromHoursSinceMidnight(NodaConstants.HoursPerDay));
+        }
     }
 }

src/NodaTime/LocalTime.cs

@@ -302,6 +302,36 @@ public static LocalTime FromSecondsSinceMidnight(int seconds)
             return new LocalTime(unchecked(seconds * NanosecondsPerSecond));
         }
 
+        /// <summary>
+        /// Factory method for creating a local time from the number of minutes which have elapsed since midnight.
+        /// </summary>
+        /// <param name="minutes">The number of minutes, in the range [0, 1439]</param>
+        /// <returns>The resulting time.</returns>
+        public static LocalTime FromMinutesSinceMidnight(int minutes)
+        {
+            // Avoid the method calls which give a decent exception unless we're actually going to fail.
+            if (minutes < 0 || minutes > MinutesPerDay - 1)
+            {
+                Preconditions.CheckArgumentRange(nameof(minutes), minutes, 0, MinutesPerDay - 1);
+            }
+            return new LocalTime(unchecked(minutes * NanosecondsPerMinute));
+        }
+
+        /// <summary>
+        /// Factory method for creating a local time from the number of hours which have elapsed since midnight.
+        /// </summary>
+        /// <param name="hours">The number of hours, in the range [0, 23]</param>
+        /// <returns>The resulting time.</returns>
+        public static LocalTime FromHoursSinceMidnight(int hours)
+        {
+            // Avoid the method calls which give a decent exception unless we're actually going to fail.
+            if (hours < 0 || hours > HoursPerDay - 1)
+            {
+                Preconditions.CheckArgumentRange(nameof(hours), hours, 0, HoursPerDay - 1);
+            }
+            return new LocalTime(unchecked(hours * NanosecondsPerHour));
+        }
+
         /// <summary>
         /// Gets the hour of day of this local time, in the range 0 to 23 inclusive.
         /// </summary>