test: cover the front ends of the explorer

.github/workflows/ci.yml

@@ -69,7 +69,7 @@ jobs:
           python-version: ${{ matrix.python-version }}
           cache: pip
       - name: Install dependencies
-        run: pip install -e ".[dev,export]"
+        run: pip install -e ".[dev,export,notebook]"
       - name: Prepare test cases
         run: cd tests/cases && for f in *.tgz; do tar -xzvf "$f"; done
       - name: Run tests

fdsreader/explorer/cli.py

@@ -123,12 +123,18 @@ def render_slice(fields, state, height, width, ramp):
 def save_figure(fields, state, series, path, height, width):
     """Write the current view to an image or an animation, using matplotlib."""
     try:
-        import matplotlib
-
-        matplotlib.use("Agg")
-        import matplotlib.pyplot as plt
+        # A figure with its own Agg canvas, rather than pyplot, leaves the backend of the process alone, e.g. when
+        # this is called from a notebook
+        from matplotlib.backends.backend_agg import FigureCanvasAgg
+        from matplotlib.figure import Figure
     except ModuleNotFoundError:
         raise SystemExit(f'{PROG}: --save needs matplotlib: pip install "fdsreader[notebook]"')
+
+    def new_figure(**kwargs):
+        fig = Figure(**kwargs)
+        FigureCanvasAgg(fig)
+        return fig
+
     from .plots import plot_series, plot_slice
 
     field = state.field(fields)
@@ -140,7 +146,8 @@ def save_figure(fields, state, series, path, height, width):
         from matplotlib import animation
 
         steps = range(0, len(field.times), max(1, len(field.times) // 120))
-        fig, ax = plt.subplots()
+        fig = new_figure()
+        ax = fig.subplots()
 
         def draw(step):
             ax.clear()
@@ -164,12 +171,11 @@ def draw(step):
             anim.save(str(path), writer=writer)
         except Exception as exc:
             raise SystemExit(f"{PROG}: could not write {path}: {exc}")
-        plt.close(fig)
         return f"wrote {path} ({len(list(steps))} frames)"
 
-    panels = (1 if field is None else 1) + (1 if series else 0)
-    fig, axes = plt.subplots(1, max(1, panels), figsize=(7 * max(1, panels), 5.5))
-    axes = np.atleast_1d(axes)
+    panels = (0 if field is None else 1) + (1 if series else 0)
+    fig = new_figure(figsize=(7 * max(1, panels), 5.5))
+    axes = np.atleast_1d(fig.subplots(1, max(1, panels)))
     at = 0
     if field is not None:
         timestep = state.clamp(fields)
@@ -191,7 +197,6 @@ def draw(step):
         plot_series(series, ax=axes[at], cursor_time=state.time(fields) if field is not None else None)
     fig.tight_layout()
     fig.savefig(str(path), dpi=150)
-    plt.close(fig)
     return f"wrote {path}"
 
 

fdsreader/explorer/notebook.py

@@ -667,9 +667,10 @@ def _on_simulation_loaded(self, sim):
             self._setup_fields(sim)
             return
 
-        self.summary.value = self._overview()
-        self._setup_fields(sim)  # also positions the time bar
-        self._refresh_curves()
+        self._setup_fields(sim)  # also positions the time bar, and draws the curves when there is a slice
+        self.summary.value = self._overview()  # after the fields, so it can count the slices
+        if not self.fields:
+            self._refresh_curves()
 
     def _overview(self):
         """Short HTML summary: what is in this simulation, at a glance."""

tests/explorer/conftest.py

@@ -55,15 +55,12 @@ def __init__(self, nx=8, ny=16, n_t=3, quantity="TEMPERATURE", unit="C"):
         self.unit = unit
         self.times = np.linspace(0.0, 2.0, n_t)
         self.axes = ("y", "z")
-        self.coords = {"x": np.array([0.0]),
-                       "y": np.linspace(-2.0, 2.0, nx),
-                       "z": np.linspace(0.0, 8.0, ny)}
+        self.coords = {"x": np.array([0.0]), "y": np.linspace(-2.0, 2.0, nx), "z": np.linspace(0.0, 8.0, ny)}
         self.shape = (nx, ny)
         # a blob that rises and grows, so frames differ both in where the heat is and
         # in how hot it gets -- which is what makes a per-step colour scale visible
         yy, zz = np.meshgrid(self.coords["y"], self.coords["z"], indexing="ij")
-        self._frames = [20 + (150 + 180 * k) * np.exp(-(yy ** 2) - (zz - 1 - 2 * k) ** 2)
-                        for k in range(n_t)]
+        self._frames = [20 + (150 + 180 * k) * np.exp(-(yy**2) - (zz - 1 - 2 * k) ** 2) for k in range(n_t)]
 
     def frame(self, timestep):
         return self._frames[timestep]
@@ -90,12 +87,26 @@ def fake_field():
 def fake_series():
     times = np.linspace(0.0, 4.0, 21)
     return [
-        {"label": "DEVC  A — TEMPERATURE [C]", "name": "A", "times": times,
-         "values": 20 + 10 * times, "quantity": "TEMPERATURE", "unit": "C",
-         "source": "device", "device": None},
-        {"label": "DEVC  B — TEMPERATURE [C]", "name": "B", "times": times,
-         "values": 20 + 4 * times ** 2, "quantity": "TEMPERATURE", "unit": "C",
-         "source": "device", "device": None},
+        {
+            "label": "DEVC  A — TEMPERATURE [C]",
+            "name": "A",
+            "times": times,
+            "values": 20 + 10 * times,
+            "quantity": "TEMPERATURE",
+            "unit": "C",
+            "source": "device",
+            "device": None,
+        },
+        {
+            "label": "DEVC  B — TEMPERATURE [C]",
+            "name": "B",
+            "times": times,
+            "values": 20 + 4 * times**2,
+            "quantity": "TEMPERATURE",
+            "unit": "C",
+            "source": "device",
+            "device": None,
+        },
     ]
 
 
@@ -110,9 +121,7 @@ def devc_without_data(request, tmp_path):
     root = tmp_path / request.param
     root.mkdir()
     (root / "c.smv").write_text(
-        "CHID\n c\n\n"
-        "CSVF\n devc\n c_devc.csv\n\n"
-        "DEVICE\n TC % TEMPERATURE\n 1.0 0.0 1.0 0.0 0.0 1.0\n"
+        "CHID\n c\n\nCSVF\n devc\n c_devc.csv\n\nDEVICE\n TC % TEMPERATURE\n 1.0 0.0 1.0 0.0 0.0 1.0\n"
     )
     if request.param == "empty":
         (root / "c_devc.csv").write_text("")
@@ -149,3 +158,24 @@ def devc_line_case(tmp_path):
     (root / "c_devc.csv").write_text("s,C\nTime,TC\n0.0,20.0\n1.0,30.0\n2.0,45.0\n")
     (root / "c_line.csv").write_text("m,C\nHeight,LINE\n0.5,100.0\n1.5,200.0\n")
     return root
+
+
+@pytest.fixture
+def app(monkeypatch, fake_field, fake_series):
+    """An interactive application over one field shown twice and two curves."""
+    from explorer_helpers import FakeSim
+
+    from fdsreader.explorer import tui
+
+    monkeypatch.setattr(tui, "fields_of", lambda sim: [fake_field, fake_field])
+    monkeypatch.setattr(tui, "build_series", lambda sim: fake_series)
+    return tui.Interactive(FakeSim())
+
+
+@pytest.fixture
+def agg():
+    """Draw on the Agg backend, so no display is needed, and close every figure afterwards."""
+    plt = pytest.importorskip("matplotlib.pyplot")
+    plt.switch_backend("Agg")
+    yield plt
+    plt.close("all")

tests/explorer/explorer_helpers.py

@@ -0,0 +1,17 @@
+"""Helpers shared by the explorer tests."""
+
+from fdsreader.explorer.cli import main
+
+
+class FakeSim:
+    """Just enough of a simulation for the interactive front end when fields and series are patched in."""
+
+    chid = "fake"
+    root_path = "."
+
+
+def run(capsys, *argv):
+    """Run the CLI and return (exit status, stdout, stderr)."""
+    status = main([str(a) for a in argv])
+    captured = capsys.readouterr()
+    return status, captured.out, captured.err

tests/explorer/test_cli.py

@@ -3,15 +3,7 @@
 import json
 
 import pytest
-
-from fdsreader.explorer.cli import main
-
-
-def run(capsys, *argv):
-    """Run the CLI and return (exit status, stdout, stderr)."""
-    status = main([str(a) for a in argv])
-    captured = capsys.readouterr()
-    return status, captured.out, captured.err
+from explorer_helpers import run
 
 
 def test_overview(tiny_case, capsys):
@@ -40,7 +32,7 @@ def test_curve_is_drawn_with_axes_and_a_legend(tiny_case, capsys):
     assert lines[0].startswith("       100 |")
     assert lines[0].rstrip().endswith("*")
     assert lines[0].split("|", 1)[1].startswith(" ")
-    assert lines[-4].startswith("        20 |*")   # and the bottom row starts at t = 0
+    assert lines[-4].startswith("        20 |*")  # and the bottom row starts at t = 0
     assert lines[-3].startswith("          +---")  # then the axis rule
     assert "t [s]" in lines[-2]
     assert lines[-1] == "  *  DEVC  TC_1 — TEMPERATURE [C]"
@@ -59,8 +51,7 @@ def test_mixed_units_are_flagged(tiny_case, capsys):
 
 def test_cursor_is_drawn_at_the_requested_time(tiny_case, capsys):
     _, without, _ = run(capsys, tiny_case, "--curve", "TC_1", "--width", "20")
-    _, with_cursor, _ = run(capsys, tiny_case, "--curve", "TC_1", "--width", "20",
-                            "--time", "5")
+    _, with_cursor, _ = run(capsys, tiny_case, "--curve", "TC_1", "--width", "20", "--time", "5")
     assert with_cursor.count("|") > without.count("|")