test(ssd1327): Improve mock scenarios beyond smoke tests. (#301)

* test(ssd1327): Improve mock scenarios beyond smoke tests.

* test(ssd1327): Fix Copilot review comments on mock tests.

Author: nedseb

.gitignore

@@ -10,3 +10,4 @@ CLAUDE.md
 .build/
 .venv/
 .claude/
+.codex

tests/fake_machine/framebuf_stub.py

@@ -18,13 +18,54 @@ def fill(self, col):
             self.buffer[i] = val
 
     def pixel(self, x, y, col=None):
-        pass
+        # GS4_HMSB: 2 pixels per byte, high nibble first
+        idx = (y * self.width + x) // 2
+        if col is None:
+            byte = self.buffer[idx]
+            return (byte >> 4) & 0x0F if x % 2 == 0 else byte & 0x0F
+        byte = self.buffer[idx]
+        if x % 2 == 0:
+            self.buffer[idx] = ((col & 0x0F) << 4) | (byte & 0x0F)
+        else:
+            self.buffer[idx] = (byte & 0xF0) | (col & 0x0F)
 
     def text(self, string, x, y, col=15):
         pass
 
     def line(self, x1, y1, x2, y2, col):
-        pass
+        # Bresenham's line algorithm (simplified)
+        dx = abs(x2 - x1)
+        dy = abs(y2 - y1)
+        sx = 1 if x1 < x2 else -1
+        sy = 1 if y1 < y2 else -1
+        err = dx - dy
+        while True:
+            self.pixel(x1, y1, col)
+            if x1 == x2 and y1 == y2:
+                break
+            e2 = 2 * err
+            if e2 > -dy:
+                err -= dy
+                x1 += sx
+            if e2 < dx:
+                err += dx
+                y1 += sy
 
     def scroll(self, dx, dy):
-        pass
+        # Shift buffer content by (dx, dy) pixels
+        buf_size = self.width * self.height // 2
+        new_buf = bytearray(buf_size)
+        for y in range(self.height):
+            for x in range(self.width):
+                src_x = x - dx
+                src_y = y - dy
+                if 0 <= src_x < self.width and 0 <= src_y < self.height:
+                    col = self.pixel(src_x, src_y)
+                    # Write to new buffer directly
+                    idx = (y * self.width + x) // 2
+                    byte = new_buf[idx]
+                    if x % 2 == 0:
+                        new_buf[idx] = (col << 4) | (byte & 0x0F)
+                    else:
+                        new_buf[idx] = (byte & 0xF0) | (col & 0x0F)
+        self.buffer[:] = new_buf

tests/scenarios/ssd1327.yaml

@@ -18,6 +18,8 @@ hardware_init: |
   dev = WS_OLED_128X128_SPI(spi, dc, res, cs)
 
 tests:
+  # ----- Mock: Smoke tests -----
+
   - name: "Fill black does not crash"
     action: call
     method: fill
@@ -36,28 +38,184 @@ tests:
     args: ["Test", 0, 0, 15]
     mode: [mock]
 
-  - name: "Power off does not crash"
+  - name: "Show does not crash"
+    action: call
+    method: show
+    mode: [mock]
+
+  # ----- Mock: Verify power_off sends correct commands -----
+
+  - name: "Power off sends FN_SELECT_A disable and DISP off"
     action: script
     script: |
+      i2c.clear_write_log()
       dev.power_off()
-      result = True
+      log = i2c.get_write_log()
+      cmds = [data[1] for reg, data in log if reg is None and len(data) == 2 and data[0] == 0x80]
+      # Expect: SET_FN_SELECT_A (0xAB), 0x00 (disable VDD), SET_DISP (0xAE)
+      result = cmds == [0xAB, 0x00, 0xAE]
     expect_true: true
     mode: [mock]
 
-  - name: "Power on does not crash"
+  # ----- Mock: Verify power_on sends correct commands -----
+
+  - name: "Power on sends FN_SELECT_A enable and DISP on"
     action: script
     script: |
-      dev.power_off()
+      i2c.clear_write_log()
       dev.power_on()
-      result = True
+      log = i2c.get_write_log()
+      cmds = [data[1] for reg, data in log if reg is None and len(data) == 2 and data[0] == 0x80]
+      # Expect: SET_FN_SELECT_A (0xAB), 0x01 (enable VDD), SET_DISP|0x01 (0xAF)
+      result = cmds == [0xAB, 0x01, 0xAF]
     expect_true: true
     mode: [mock]
 
-  - name: "Show does not crash"
-    action: call
-    method: show
+  # ----- Mock: Verify contrast command -----
+
+  - name: "Contrast sends SET_CONTRAST with value"
+    action: script
+    script: |
+      i2c.clear_write_log()
+      dev.contrast(200)
+      log = i2c.get_write_log()
+      cmds = [data[1] for reg, data in log if reg is None and len(data) == 2 and data[0] == 0x80]
+      result = cmds == [0x81, 200]
+    expect_true: true
+    mode: [mock]
+
+  # ----- Mock: Verify invert commands -----
+
+  - name: "Invert on sends SET_DISP_MODE inverted"
+    action: script
+    script: |
+      i2c.clear_write_log()
+      dev.invert(True)
+      log = i2c.get_write_log()
+      cmds = [data[1] for reg, data in log if reg is None and len(data) == 2 and data[0] == 0x80]
+      # SET_DISP_MODE (0xA4) | 0x03 = 0xA7 (inverted)
+      result = cmds == [0xA7]
+    expect_true: true
+    mode: [mock]
+
+  - name: "Invert off sends SET_DISP_MODE normal"
+    action: script
+    script: |
+      i2c.clear_write_log()
+      dev.invert(False)
+      log = i2c.get_write_log()
+      cmds = [data[1] for reg, data in log if reg is None and len(data) == 2 and data[0] == 0x80]
+      # SET_DISP_MODE (0xA4) = normal
+      result = cmds == [0xA4]
+    expect_true: true
     mode: [mock]
 
+  # ----- Mock: Verify rotate commands -----
+
+  - name: "Rotate sends offset and remap commands"
+    action: script
+    script: |
+      i2c.clear_write_log()
+      dev.rotate(True)
+      log = i2c.get_write_log()
+      cmds = [data[1] for reg, data in log if reg is None and len(data) == 2 and data[0] == 0x80]
+      # power_off + SET_DISP_OFFSET, 128, SET_SEG_REMAP, 0x42 + power_on
+      expected = [0xAB, 0x00, 0xAE, 0xA2, 128, 0xA0, 0x42, 0xAB, 0x01, 0xAF]
+      result = cmds == expected
+    expect_true: true
+    mode: [mock]
+
+  # ----- Mock: Verify show sends column/row addr + data -----
+
+  - name: "Show sends column and row address then data"
+    action: script
+    script: |
+      i2c.clear_write_log()
+      dev.show()
+      log = i2c.get_write_log()
+      cmds = [data[1] for reg, data in log if reg is None and len(data) == 2 and data[0] == 0x80]
+      # SET_COL_ADDR (0x15), col_start, col_end, SET_ROW_ADDR (0x75), row_start, row_end
+      expected_prefix = [0x15, 0x00, 0x3F, 0x75, 0x00, 0x7F]
+      # Check data was sent (writevto with 0x40 prefix) with correct payload size
+      data_writes = [data for reg, data in log if reg is None and len(data) > 2 and data[0] == 0x40]
+      expected_payload = (dev.width * dev.height) // 2
+      result = (
+          cmds[:6] == expected_prefix
+          and len(data_writes) > 0
+          and len(data_writes[0]) - 1 == expected_payload
+      )
+    expect_true: true
+    mode: [mock]
+
+  # ----- Mock: Verify pixel buffer -----
+
+  - name: "Pixel modifies framebuffer"
+    action: script
+    script: |
+      dev.fill(0)
+      dev.pixel(10, 20, 15)
+      result = dev.framebuf.pixel(10, 20) == 15
+    expect_true: true
+    mode: [mock]
+
+  - name: "Fill sets all pixels"
+    action: script
+    script: |
+      dev.fill(7)
+      result = (
+          dev.framebuf.pixel(0, 0) == 7
+          and dev.framebuf.pixel(63, 63) == 7
+          and dev.framebuf.pixel(127, 0) == 7
+          and dev.framebuf.pixel(0, 127) == 7
+          and dev.framebuf.pixel(127, 127) == 7
+      )
+    expect_true: true
+    mode: [mock]
+
+  # ----- Mock: Verify init_display sends expected command sequence -----
+
+  - name: "Init display sends unlock then display off then display on"
+    action: script
+    script: |
+      i2c.clear_write_log()
+      dev.init_display()
+      log = i2c.get_write_log()
+      cmds = [data[1] for reg, data in log if reg is None and len(data) == 2 and data[0] == 0x80]
+      # First command must be SET_COMMAND_LOCK (0xFD), then unlock (0x12)
+      # Then SET_DISP (0xAE = off), and last command must be SET_DISP|0x01 (0xAF = on)
+      result = cmds[0] == 0xFD and cmds[1] == 0x12 and cmds[2] == 0xAE and cmds[-1] == 0xAF
+    expect_true: true
+    mode: [mock]
+
+  # ----- Mock: Verify line draws on framebuffer -----
+
+  - name: "Line modifies framebuffer"
+    action: script
+    script: |
+      dev.fill(0)
+      dev.line(0, 0, 10, 0, 15)
+      # At least the start pixel should be set
+      result = dev.framebuf.pixel(0, 0) == 15
+    expect_true: true
+    mode: [mock]
+
+  # ----- Mock: Verify scroll moves framebuffer content -----
+
+  - name: "Scroll shifts pixel position"
+    action: script
+    script: |
+      dev.fill(0)
+      dev.pixel(5, 0, 15)
+      dev.scroll(1, 0)
+      # Pixel should have moved from (5,0) to (6,0)
+      moved = dev.framebuf.pixel(6, 0) == 15
+      cleared = dev.framebuf.pixel(5, 0) == 0
+      result = moved and cleared
+    expect_true: true
+    mode: [mock]
+
+  # ----- Hardware -----
+
   - name: "Display white screen"
     action: hardware_script
     script: |