Add fixed_time_pickoff unit test

tests/dsp/processors/test_fixed_time_pickoff.py

@@ -0,0 +1,69 @@
+import numpy as np
+import pytest
+
+from pygama.dsp.errors import DSPFatal
+from pygama.dsp.processors import fixed_time_pickoff
+
+
+def test_fixed_time_pickoff():
+    """Testing function for the fixed_time_pickoff processor."""
+
+    len_wf = 20
+
+    w_in = np.ones(len_wf)
+    w_in[4] = np.nan
+    assert np.isnan(fixed_time_pickoff(w_in, 1, ord("i")))
+
+    w_in = np.ones(len_wf)
+    assert np.isnan(fixed_time_pickoff(w_in, np.nan, ord("i")))
+
+    w_in = np.ones(len_wf)
+    assert np.isnan(fixed_time_pickoff(w_in, -1, ord("i")))
+
+    w_in = np.ones(len_wf)
+    assert np.isnan(fixed_time_pickoff(w_in, len_wf, ord("i")))
+
+    with pytest.raises(DSPFatal):
+        w_in = np.ones(len_wf)
+        fixed_time_pickoff(w_in, 1.5, ord("i"))
+
+    with pytest.raises(DSPFatal):
+        w_in = np.ones(len_wf)
+        fixed_time_pickoff(w_in, 1.5, ord(" "))
+
+    # linear tests
+    w_in = np.arange(len_wf, dtype=float)
+    assert fixed_time_pickoff(w_in, 3, ord("i")) == 3
+
+    chars = ["n", "f", "c", "l", "h", "s"]
+    sols = [4, 3, 4, 3.5, 3.5, 3.5]
+
+    for char, sol in zip(chars, sols):
+        assert fixed_time_pickoff(w_in, 3.5, ord(char)) == sol
+
+    # sine wave tests
+    w_in = np.sin(np.arange(len_wf))
+
+    chars = ["n", "f", "c", "l", "h", "s"]
+    sols = [
+        0.1411200080598672,
+        0.1411200080598672,
+        -0.7568024953079282,
+        -0.08336061778208165,
+        -0.09054574599004982,
+        -0.10707938709427486,
+    ]
+
+    for char, sol in zip(chars, sols):
+        assert np.isclose(fixed_time_pickoff(w_in, 3.25, ord(char)), sol)
+
+    # last few corner cases of 'h'
+    w_in = np.sin(np.arange(len_wf))
+    ftps = [0.2, len_wf - 1.8]
+    sols = [
+        0.1806725096462211,
+        -0.6150034250096629,
+    ]
+
+    for ftp, sol in zip(ftps, sols):
+        assert np.isclose(fixed_time_pickoff(w_in, ftp, ord("h")), sol)