Coverage for tests/test_time_utils.py: 15%

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15# This program is free software: you can redistribute it and/or modify 

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27 

28"""Unit tests for methods in butler.time module. 

29""" 

30 

31import unittest 

32import warnings 

33 

34# As of astropy 4.2, the erfa interface is shipped independently and 

35# ErfaWarning is no longer an AstropyWarning 

36try: 

37 import erfa 

38except ImportError: 

39 erfa = None 

40 

41import astropy.utils.exceptions 

42from astropy.time import Time, TimeDelta 

43from lsst.daf.butler.time_utils import TimeConverter 

44 

45 

46class TimeTestCase(unittest.TestCase): 

47 """A test case for time module""" 

48 

49 def test_time_before_epoch(self): 

50 """Tests for before-the-epoch time.""" 

51 time = Time("1950-01-01T00:00:00", format="isot", scale="tai") 

52 value = TimeConverter().astropy_to_nsec(time) 

53 self.assertEqual(value, 0) 

54 

55 value = TimeConverter().nsec_to_astropy(value) 

56 self.assertEqual(value, TimeConverter().epoch) 

57 

58 def test_max_time(self): 

59 """Tests for after-the-end-of-astronomy time.""" 

60 # there are rounding issues, need more complex comparison 

61 time = Time("2101-01-01T00:00:00", format="isot", scale="tai") 

62 value = TimeConverter().astropy_to_nsec(time) 

63 

64 value_max = TimeConverter().astropy_to_nsec(TimeConverter().max_time) 

65 self.assertEqual(value, value_max) 

66 

67 # Astropy will give "dubious year" for UTC five years in the future 

68 # so hide these expected warnings from the test output 

69 with warnings.catch_warnings(): 

70 warnings.simplefilter("ignore", category=astropy.utils.exceptions.AstropyWarning) 

71 if erfa is not None: 

72 warnings.simplefilter("ignore", category=erfa.ErfaWarning) 

73 time = Time("2101-01-01T00:00:00", format="isot", scale="utc") 

74 

75 # unittest can't test for no warnings so we run the test and 

76 # trigger our own warning and count all the warnings 

77 with self.assertWarns(Warning) as cm: 

78 TimeConverter().astropy_to_nsec(time) 

79 warnings.warn("deliberate", stacklevel=1) 

80 self.assertEqual(str(cm.warning), "deliberate") 

81 

82 def test_round_trip(self): 

83 """Test precision of round-trip conversion.""" 

84 # do tests at random points between epoch and max. time 

85 times = [ 

86 "1970-01-01T12:00:00.123", 

87 "1999-12-31T23:59:57.123456", 

88 "2000-01-01T12:00:00.123456", 

89 "2030-01-01T12:00:00.123456789", 

90 "2075-08-17T00:03:45", 

91 "2099-12-31T23:00:50", 

92 ] 

93 for time in times: 

94 atime = Time(time, format="isot", scale="tai") 

95 for sec in range(7): 

96 # loop over few seconds to add to each time 

97 for i in range(100): 

98 # loop over additional fractions of seconds 

99 delta = sec + 0.3e-9 * i 

100 in_time = atime + TimeDelta(delta, format="sec") 

101 # do round-trip conversion to nsec and back 

102 value = TimeConverter().astropy_to_nsec(in_time) 

103 value = TimeConverter().nsec_to_astropy(value) 

104 delta2 = value - in_time 

105 delta2_sec = delta2.to_value("sec") 

106 # absolute precision should be better than half 

107 # nanosecond, but there are rounding errors too 

108 self.assertLess(abs(delta2_sec), 0.51e-9) 

109 

110 def test_times_equal(self): 

111 """Test for times_equal method""" 

112 # time == time should always work 

113 time1 = Time("2000-01-01T00:00:00.123456789", format="isot", scale="tai") 

114 self.assertTrue(TimeConverter().times_equal(time1, time1)) 

115 

116 # one nsec difference 

117 time1 = Time("2000-01-01T00:00:00.123456789", format="isot", scale="tai") 

118 time2 = Time("2000-01-01T00:00:00.123456788", format="isot", scale="tai") 

119 self.assertTrue(TimeConverter().times_equal(time1, time2, 2.0)) 

120 self.assertTrue(TimeConverter().times_equal(time2, time1, 2.0)) 

121 self.assertFalse(TimeConverter().times_equal(time1, time2, 0.5)) 

122 self.assertFalse(TimeConverter().times_equal(time2, time1, 0.5)) 

123 

124 # one nsec difference, times in UTC 

125 time1 = Time("2000-01-01T00:00:00.123456789", format="isot", scale="utc") 

126 time2 = Time("2000-01-01T00:00:00.123456788", format="isot", scale="utc") 

127 self.assertTrue(TimeConverter().times_equal(time1, time2, 2.0)) 

128 self.assertTrue(TimeConverter().times_equal(time2, time1, 2.0)) 

129 self.assertFalse(TimeConverter().times_equal(time1, time2, 0.5)) 

130 self.assertFalse(TimeConverter().times_equal(time2, time1, 0.5)) 

131 

132 # 1/2 nsec difference 

133 time1 = Time("2000-01-01T00:00:00.123456789", format="isot", scale="tai") 

134 time2 = time1 + TimeDelta(0.5e-9, format="sec") 

135 self.assertTrue(TimeConverter().times_equal(time1, time2)) 

136 self.assertTrue(TimeConverter().times_equal(time2, time1)) 

137 self.assertFalse(TimeConverter().times_equal(time1, time2, 0.25)) 

138 self.assertFalse(TimeConverter().times_equal(time2, time1, 0.25)) 

139 

140 # 1/2 microsec difference 

141 time1 = Time("2000-01-01T00:00:00.123456789", format="isot", scale="tai") 

142 time2 = time1 + TimeDelta(0.5e-6, format="sec") 

143 self.assertTrue(TimeConverter().times_equal(time1, time2, 501)) 

144 self.assertTrue(TimeConverter().times_equal(time2, time1, 501)) 

145 self.assertFalse(TimeConverter().times_equal(time1, time2, 499)) 

146 self.assertFalse(TimeConverter().times_equal(time2, time1, 499)) 

147 

148 # UTC vs TAI 

149 time1 = Time("2013-06-17 13:34:45.775000", scale="tai", format="iso") 

150 time2 = Time("2013-06-17T13:34:10.775", scale="utc", format="isot") 

151 self.assertTrue(TimeConverter().times_equal(time1, time2)) 

152 self.assertEqual(TimeConverter().astropy_to_nsec(time1), TimeConverter().astropy_to_nsec(time2)) 

153 

154 

155if __name__ == "__main__": 

156 unittest.main()