improve coverage

tests/node_tests/fft_1d.py

@@ -0,0 +1,68 @@
+import numpy as np
+from backend.data_types import LineData, RecordTable
+
+
+def test_fft_1d_peak_period():
+    from backend.nodes.fft_1d import FFT1D
+
+    node = FFT1D()
+
+    n = 256
+    period = 32  # pixels
+    dx = 1e-9    # 1 nm per pixel
+    t = np.arange(n, dtype=np.float64)
+    signal = np.sin(2 * np.pi * t / period)
+    profile = LineData(
+        data=signal,
+        x_axis=t * dx,
+        x_unit="m",
+        y_unit="V",
+    )
+
+    freq_line, table = node.process(profile)
+
+    assert isinstance(freq_line, LineData)
+    assert isinstance(table, RecordTable)
+    assert len(table) == 1
+    assert table[0]["quantity"] == "Peak period"
+    assert table[0]["unit"] == "m"
+
+    # Peak period should be close to 32 nm
+    expected = period * dx
+    assert abs(table[0]["value"] - expected) / expected < 0.1
+
+    # Output axis is in metres (spatial units)
+    assert freq_line.x_unit == "m"
+    # Spectrum values are non-negative magnitudes
+    assert np.all(freq_line.data >= 0)
+    # Highest spectral value corresponds to peak period
+    peak_idx = np.argmax(freq_line.data)
+    assert abs(freq_line.x_axis[peak_idx] - expected) / expected < 0.1
+
+
+def test_fft_1d_no_x_axis():
+    from backend.nodes.fft_1d import FFT1D
+
+    node = FFT1D()
+
+    # Plain numpy array without calibration — should fall back to d=1, unit="m"
+    signal = np.sin(2 * np.pi * np.arange(64) / 8)
+    freq_line, table = node.process(signal)
+
+    assert isinstance(freq_line, LineData)
+    assert len(freq_line.data) > 0
+    assert np.all(freq_line.data >= 0)
+    assert len(table) == 1
+
+
+def test_fft_1d_output_length():
+    from backend.nodes.fft_1d import FFT1D
+
+    node = FFT1D()
+
+    for n in (32, 64, 128):
+        data = np.random.default_rng(n).standard_normal(n)
+        profile = LineData(data=data, x_axis=np.arange(n, dtype=np.float64) * 1e-9, x_unit="m")
+        freq_line, _ = node.process(profile)
+        # rfft gives n//2+1 bins; DC (index 0) is removed, leaving n//2 points
+        assert len(freq_line.data) == n // 2