Examples

This page walks through the built-in examples shipped with pypts. They are located under src/pypts/examples/ and src/pypts/example_tests.py.

Sinewave Validation Example

This example demonstrates the complete pypts workflow — from a test method that produces a matplotlib plot, through the recipe YAML that wires the step up, to the HTML report that embeds the chart automatically.

What it does

1. A Python test method generates a 60 Hz sinewave, analyses its frequency content with an FFT, and saves a two-panel plot (time domain + spectrum) to a temporary PNG file.

2. The recipe step maps the returned image path with type: image so the framework copies the file into the report directory.

3. The HTML report embeds the chart at the bottom of the page, captioned with the step name and PASS/FAIL result.

Test method (example_tests.py)

import tempfile
import numpy as np
import matplotlib
matplotlib.use('Agg')          # non-interactive backend — safe in a test thread
import matplotlib.pyplot as plt

def generate_sinewave(frequency=60, duration=1.0, tolerance=1.0):
    sampling_rate = frequency * 10
    t    = np.linspace(0, duration, int(sampling_rate * duration), endpoint=False)
    data = np.sin(2 * np.pi * frequency * t)

    # FFT analysis
    fft_result = np.fft.fft(data)
    fft_freq   = np.fft.fftfreq(len(data), 1 / sampling_rate)
    magnitude  = np.abs(fft_result[: len(fft_result) // 2])
    freq_bins  = fft_freq[: len(fft_freq) // 2]
    detected   = abs(freq_bins[np.argmax(magnitude)])
    test_passed = abs(detected - frequency) <= tolerance

    # Build plot
    fig, (ax1, ax2) = plt.subplots(2, 1, figsize=(10, 6))
    ax1.plot(t, data, linewidth=0.8)
    ax1.set(xlabel="Time (s)", ylabel="Amplitude",
            title=f"Sinewave — {frequency} Hz")
    ax1.grid(True, alpha=0.3)

    ax2.plot(freq_bins, magnitude, linewidth=0.8)
    ax2.axvline(detected, color="red", linestyle="--",
                label=f"Peak: {detected:.1f} Hz")
    ax2.set(xlabel="Frequency (Hz)", ylabel="Magnitude", title="FFT Spectrum")
    ax2.legend()
    ax2.grid(True, alpha=0.3)

    plt.tight_layout()
    tmp = tempfile.NamedTemporaryFile(suffix="_sinewave.png", delete=False)
    fig.savefig(tmp.name, dpi=100, bbox_inches="tight")
    plt.close(fig)

    return {"passed": test_passed, "chart": tmp.name}

Key points:

• matplotlib.use('Agg') must be called before importing pyplot — the Agg backend renders to a file without opening a display window, which is required inside a test thread.

• tempfile.NamedTemporaryFile(delete=False) creates the file in the OS temporary directory and keeps it on disk after the function returns. The framework copies it into the report directory, so the caller does not need to manage the temporary file’s lifetime.

• The method returns a plain dict. The chart key holds the absolute path to the PNG; passed is the boolean verdict.

Recipe step (Minimal_setup_recipe.yml)

- steptype: PythonModuleStep
  step_name: Sinewave test (60 Hz)
  description: >
    Generate a 60 Hz sinewave, validate it via FFT,
    and attach the plot to the report.
  action_type: method
  module: example_tests.py
  method_name: generate_sinewave
  input_mapping:
    frequency: {type: direct, value: 60}
    tolerance: {type: direct, value: 1.0}
  output_mapping:
    passed: {type: passfail}   # PASS when frequency error ≤ tolerance
    chart:  {type: image}      # PNG copied into report and embedded in HTML

The type: image mapping tells pypts to:

1. Copy the file at chart’s path into <report_dir>/img/.

2. Record the relative path in the CSV report (image_paths column).

3. Embed the image in the Images section at the bottom of the HTML report, with the step name and result as a caption.

Note

type: image does not affect the step’s pass/fail verdict. The verdict comes from the passed: {type: passfail} mapping. Both output keys are independent.

HTML report output

After the recipe runs, the HTML report (pts_reports/report_<timestamp>.html) contains an Images section at the bottom:

<figure>
  <img src="img/<step_id>_<filename>_sinewave.png">
  <figcaption>
    <strong>Step:</strong> Sinewave test (60 Hz) —
    <strong>Result:</strong> PASS
  </figcaption>
</figure>

The img/ subdirectory sits next to the HTML file so the report is self-contained and portable — copy the whole pts_reports/ folder to share it.

Where to find the example files

File	Role
src/pypts/example_tests.py	Test methods (main example set)
src/pypts/recipes/simple_recipe.yml	Reference recipe with all output mapping types
src/pypts/examples/environment_setup_tools/Minimal_setup/	Minimal (file-based) setup example
src/pypts/examples/environment_setup_tools/Package_based_setup/	Package-based setup example