test(steami_screen): add basic mock tests

Add initial mock test coverage for the steami_screen driver.

## Added
- FakeDisplay backend to simulate a display device
- Basic property tests: center, radius, max_chars
- Core drawing API tests: clear, show, pixel, line, rect, text
- Text helpers: title, subtitle, value
- Widgets: bar, menu, face
- Advanced widgets smoke tests: graph, gauge, compass, watch
- Geometry helpers via public API: circle (outline and fill)
- Edge cases: empty subtitle, unknown face, invalid position fallback

Tests validate that high-level API correctly delegates to the display backend
by inspecting recorded calls.

## Notes
- Tests access the backend via `dev._d` due to runner scope limitations
- No hardware dependency (pure mock)

## Remaining work
- Validate exact layout/positions (not just call presence)
- Test scaling behavior (text scale, value rendering)
- Add snapshot/visual tests (e.g. Pillow backend)
- Add hardware tests for real displays (SSD1327, GC9A01)
- Improve coverage of edge cases (bounds, clipping, long text)

Author: Charly-sketch

lib/steami_screen/steami_screen/__init__.py

@@ -1,6 +1,5 @@
 from steami_screen.colors import rgb_to_gray4, rgb_to_rgb8, rgb_to_rgb565
-from steami_screen.gc9a01 import GC9A01Display
-from steami_screen.screen import (
+from steami_screen.device import (
     BLACK,
     BLUE,
     DARK,
@@ -12,6 +11,7 @@
     YELLOW,
     Screen,
 )
+from steami_screen.gc9a01 import GC9A01Display
 from steami_screen.sssd1327 import SSD1327Display
 
 __all__ = [

lib/steami_screen/steami_screen/screen.py lib/steami_screen/steami_screen/device.pylib/steami_screen/steami_screen/screen.py renamed to lib/steami_screen/steami_screen/device.py

@@ -0,0 +1,382 @@
+driver: steami_screen
+driver_class: Screen
+
+mock_init: |
+  class FakeDisplay:
+      def __init__(self):
+          self.calls = []
+          self.width = 128
+          self.height = 128
+
+      def fill(self, color):
+          self.calls.append(("fill", color))
+
+      def pixel(self, x, y, color):
+          self.calls.append(("pixel", x, y, color))
+
+      def text(self, text, x, y, color):
+          self.calls.append(("text", text, x, y, color))
+
+      def line(self, x1, y1, x2, y2, color):
+          self.calls.append(("line", x1, y1, x2, y2, color))
+
+      def fill_rect(self, x, y, w, h, color):
+          self.calls.append(("fill_rect", x, y, w, h, color))
+
+      def rect(self, x, y, w, h, color):
+          self.calls.append(("rect", x, y, w, h, color))
+
+      def show(self):
+          self.calls.append(("show",))
+
+      def clear_calls(self):
+          self.calls = []
+
+  dev = Screen(FakeDisplay())
+
+tests:
+  - name: "Center is computed correctly"
+    action: script
+    script: |
+      result = dev.center == (64, 64)
+    expect_true: true
+    mode: [mock]
+
+  - name: "Radius is computed correctly"
+    action: script
+    script: |
+      result = dev.radius == 64
+    expect_true: true
+    mode: [mock]
+
+  - name: "Max chars matches screen width"
+    action: script
+    script: |
+      result = dev.max_chars == 16
+    expect_true: true
+    mode: [mock]
+
+  - name: "clear calls backend fill"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.clear()
+      result = len(d.calls) == 1 and d.calls[0][0] == "fill"
+    expect_true: true
+    mode: [mock]
+
+  - name: "show calls backend show"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.show()
+      result = len(d.calls) == 1 and d.calls[0][0] == "show"
+    expect_true: true
+    mode: [mock]
+
+  - name: "pixel calls backend pixel"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.pixel(10, 20)
+      result = d.calls == [("pixel", 10, 20, (255, 255, 255))]
+    expect_true: true
+    mode: [mock]
+
+  - name: "line calls backend line"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.line(1, 2, 30, 40)
+      result = d.calls == [("line", 1, 2, 30, 40, (255, 255, 255))]
+    expect_true: true
+    mode: [mock]
+
+  - name: "rect outline uses backend rect"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.rect(5, 6, 20, 10)
+      result = d.calls == [("rect", 5, 6, 20, 10, (255, 255, 255))]
+    expect_true: true
+    mode: [mock]
+
+  - name: "rect fill uses backend fill_rect"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.rect(5, 6, 20, 10, fill=True)
+      result = d.calls == [("fill_rect", 5, 6, 20, 10, (255, 255, 255))]
+    expect_true: true
+    mode: [mock]
+
+  - name: "text at CENTER draws backend text"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.text("Hi")
+      result = len(d.calls) >= 1 and d.calls[0][0] == "text"
+    expect_true: true
+    mode: [mock]
+
+  - name: "text at explicit coordinates uses given position"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.text("Hi", at=(12, 34))
+      result = d.calls == [("text", "Hi", 12, 34, (255, 255, 255))]
+    expect_true: true
+    mode: [mock]
+
+  - name: "text scale 2 still renders text"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.text("Hi", scale=2)
+      text_calls = [c for c in d.calls if c[0] == "text"]
+      result = len(text_calls) > 0
+    expect_true: true
+    mode: [mock]
+
+  - name: "title draws text near north position"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.title("Hello")
+      text_calls = [c for c in d.calls if c[0] == "text"]
+      result = len(text_calls) == 1 and text_calls[0][1] == "Hello"
+    expect_true: true
+    mode: [mock]
+
+  - name: "subtitle with one line draws one text call"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.subtitle("Bottom")
+      text_calls = [c for c in d.calls if c[0] == "text"]
+      result = len(text_calls) == 1 and text_calls[0][1] == "Bottom"
+    expect_true: true
+    mode: [mock]
+
+  - name: "subtitle with multiple lines draws multiple text calls"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.subtitle("Line1", "Line2", "Line3")
+      text_calls = [c for c in d.calls if c[0] == "text"]
+      labels = [c[1] for c in text_calls]
+      result = len(text_calls) == 3 and labels == ["Line1", "Line2", "Line3"]
+    expect_true: true
+    mode: [mock]
+
+  - name: "subtitle with no lines does nothing"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.subtitle()
+      result = len(d.calls) == 0
+    expect_true: true
+    mode: [mock]
+
+  - name: "value draws main value"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.value(42)
+      text_calls = [c for c in d.calls if c[0] == "text"]
+      result = len(text_calls) > 0
+    expect_true: true
+    mode: [mock]
+
+  - name: "value with label draws label and value"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.value(42, label="Temp")
+      text_calls = [c for c in d.calls if c[0] == "text"]
+      labels = [c[1] for c in text_calls]
+      result = "Temp" in labels
+    expect_true: true
+    mode: [mock]
+
+  - name: "value with unit draws extra text"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.value(42, unit="C")
+      text_calls = [c for c in d.calls if c[0] == "text"]
+      labels = [c[1] for c in text_calls]
+      result = "C" in labels
+    expect_true: true
+    mode: [mock]
+
+  - name: "bar draws background and fill"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.bar(50, max_val=100)
+      fill_calls = [c for c in d.calls if c[0] == "fill_rect"]
+      result = len(fill_calls) == 2
+    expect_true: true
+    mode: [mock]
+
+  - name: "bar with zero value only draws background"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.bar(0, max_val=100)
+      fill_calls = [c for c in d.calls if c[0] == "fill_rect"]
+      result = len(fill_calls) == 1
+    expect_true: true
+    mode: [mock]
+
+  - name: "menu draws all visible items"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.menu(["A", "B", "C"], selected=1)
+      text_calls = [c for c in d.calls if c[0] == "text"]
+      labels = [c[1] for c in text_calls]
+      result = len(text_calls) == 3 and "> B" in labels
+    expect_true: true
+    mode: [mock]
+
+  - name: "face happy draws filled pixels"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.face("happy")
+      fill_calls = [c for c in d.calls if c[0] == "fill_rect"]
+      result = len(fill_calls) > 0
+    expect_true: true
+    mode: [mock]
+
+  - name: "face custom bitmap draws filled pixels"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.face((0xFF, 0x81, 0x81, 0x81, 0x81, 0x81, 0x81, 0xFF))
+      fill_calls = [c for c in d.calls if c[0] == "fill_rect"]
+      result = len(fill_calls) > 0
+    expect_true: true
+    mode: [mock]
+
+  - name: "face unknown expression does nothing"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.face("unknown")
+      result = len(d.calls) == 0
+    expect_true: true
+    mode: [mock]
+
+  - name: "graph with one point draws axes and value without crashing"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.graph([12], min_val=0, max_val=100)
+      result = len(d.calls) > 0
+    expect_true: true
+    mode: [mock]
+
+  - name: "graph with multiple points draws line segments"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.graph([10, 20, 15, 30], min_val=0, max_val=40)
+      line_calls = [c for c in d.calls if c[0] == "line"]
+      result = len(line_calls) > 0
+    expect_true: true
+    mode: [mock]
+
+  - name: "gauge draws arc and labels"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.gauge(50, min_val=0, max_val=100)
+      pixel_calls = [c for c in d.calls if c[0] == "pixel"]
+      text_calls = [c for c in d.calls if c[0] == "text"]
+      result = len(pixel_calls) > 0 and len(text_calls) > 0
+    expect_true: true
+    mode: [mock]
+
+  - name: "compass draws needle and labels"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.compass(90)
+      text_calls = [c for c in d.calls if c[0] == "text"]
+      line_calls = [c for c in d.calls if c[0] == "line"]
+      result = len(text_calls) >= 4 and len(line_calls) > 0
+    expect_true: true
+    mode: [mock]
+
+  - name: "watch draws clock face"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.watch(10, 15, 30)
+      text_calls = [c for c in d.calls if c[0] == "text"]
+      line_calls = [c for c in d.calls if c[0] == "line"]
+      result = len(text_calls) >= 4 and len(line_calls) > 0
+    expect_true: true
+    mode: [mock]
+
+  - name: "Resolve invalid cardinal falls back to center"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.text("X", at="INVALID")
+      result = len(d.calls) == 1 and d.calls[0][0] == "text"
+    expect_true: true
+    mode: [mock]
+
+  - name: "circle outline draws pixels"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.circle(64, 64, 10)
+      pixel_calls = [c for c in d.calls if c[0] == "pixel"]
+      result = len(pixel_calls) > 0
+    expect_true: true
+    mode: [mock]
+
+  - name: "circle fill draws lines"
+    action: script
+    script: |
+      d = dev._d
+      d.clear_calls()
+      dev.circle(64, 64, 10, fill=True)
+      line_calls = [c for c in d.calls if c[0] == "line"]
+      result = len(line_calls) > 0
+    expect_true: true
+    mode: [mock]