diff --git a/local/recipes/gpu/redox-drm/source/src/kms/connector.rs b/local/recipes/gpu/redox-drm/source/src/kms/connector.rs
index d43f7dc5..d37422d7 100644
--- a/local/recipes/gpu/redox-drm/source/src/kms/connector.rs
+++ b/local/recipes/gpu/redox-drm/source/src/kms/connector.rs
@@ -44,3 +44,42 @@ pub fn synthetic_edid() -> Vec<u8> {
         0x44, 0x50, 0x0a, 0x20, 0x20, 0x00, 0xa7,
     ]
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn synthetic_displayport_has_correct_fields() {
+        let conn = Connector::synthetic_displayport(5, 10);
+        assert_eq!(conn.info.id, 5);
+        assert_eq!(conn.info.encoder_id, 10);
+        assert_eq!(conn.info.connector_type, ConnectorType::DisplayPort);
+        assert_eq!(conn.info.connection, ConnectorStatus::Connected);
+        assert!(!conn.info.modes.is_empty(), "synthetic DisplayPort should have modes");
+    }
+
+    #[test]
+    fn synthetic_displayport_modes_have_valid_dimensions() {
+        let conn = Connector::synthetic_displayport(1, 1);
+        for mode in &conn.info.modes {
+            assert!(mode.hdisplay > 0, "mode hdisplay should be > 0");
+            assert!(mode.vdisplay > 0, "mode vdisplay should be > 0");
+            assert!(mode.vrefresh > 0, "mode vrefresh should be > 0");
+            assert!(mode.clock > 0, "mode clock should be > 0");
+        }
+    }
+
+    #[test]
+    fn synthetic_edid_returns_exactly_112_bytes() {
+        let edid = synthetic_edid();
+        assert_eq!(edid.len(), 112);
+    }
+
+    #[test]
+    fn synthetic_edid_has_valid_header() {
+        let edid = synthetic_edid();
+        let header: [u8; 8] = [0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00];
+        assert_eq!(&edid[0..8], &header, "EDID header should be valid");
+    }
+}
diff --git a/local/recipes/gpu/redox-drm/source/src/kms/crtc.rs b/local/recipes/gpu/redox-drm/source/src/kms/crtc.rs
index 7ff39660..dc474763 100644
--- a/local/recipes/gpu/redox-drm/source/src/kms/crtc.rs
+++ b/local/recipes/gpu/redox-drm/source/src/kms/crtc.rs
@@ -41,3 +41,67 @@ impl Crtc {
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn test_mode() -> ModeInfo {
+        ModeInfo::default_1080p()
+    }
+
+    #[test]
+    fn new_initializes_correctly() {
+        let crtc = Crtc::new(42);
+        assert_eq!(crtc.id, 42);
+        assert_eq!(crtc.current_fb, 0);
+        assert!(crtc.connectors.is_empty());
+        assert!(crtc.mode.is_none());
+        assert_eq!(crtc.gamma_size, 256);
+    }
+
+    #[test]
+    fn program_sets_fb_connectors_and_mode() {
+        let mut crtc = Crtc::new(1);
+        let mode = test_mode();
+        let result = crtc.program(99, &[10, 20], &mode);
+
+        assert!(result.is_ok());
+        assert_eq!(crtc.current_fb, 99);
+        assert_eq!(crtc.connectors, vec![10, 20]);
+        assert!(crtc.mode.is_some());
+        let programmed_mode = crtc.mode.unwrap();
+        assert_eq!(programmed_mode.hdisplay, 1920);
+        assert_eq!(programmed_mode.vdisplay, 1080);
+    }
+
+    #[test]
+    fn program_empty_connectors_returns_invalid_argument() {
+        let mut crtc = Crtc::new(1);
+        let mode = test_mode();
+        let result = crtc.program(99, &[], &mode);
+
+        assert!(result.is_err());
+        match result.unwrap_err() {
+            DriverError::InvalidArgument(msg) => {
+                assert!(msg.contains("connector"));
+            }
+            other => panic!("expected InvalidArgument, got {:?}", other),
+        }
+        // State should be unchanged
+        assert_eq!(crtc.current_fb, 0);
+        assert!(crtc.connectors.is_empty());
+        assert!(crtc.mode.is_none());
+    }
+
+    #[test]
+    fn program_multiple_connectors_accepted() {
+        let mut crtc = Crtc::new(1);
+        let mode = test_mode();
+        let result = crtc.program(50, &[1, 2, 3, 4, 5], &mode);
+
+        assert!(result.is_ok());
+        assert_eq!(crtc.connectors.len(), 5);
+        assert_eq!(crtc.connectors, vec![1, 2, 3, 4, 5]);
+    }
+}
diff --git a/local/recipes/gpu/redox-drm/source/src/kms/mod.rs b/local/recipes/gpu/redox-drm/source/src/kms/mod.rs
index cb6494f8..d87dc481 100644
--- a/local/recipes/gpu/redox-drm/source/src/kms/mod.rs
+++ b/local/recipes/gpu/redox-drm/source/src/kms/mod.rs
@@ -180,3 +180,91 @@ pub struct EncoderInfo {
     #[allow(dead_code)]
     pub possible_clones: u32,
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn default_1080p_has_correct_values() {
+        let mode = ModeInfo::default_1080p();
+        assert_eq!(mode.hdisplay, 1920);
+        assert_eq!(mode.vdisplay, 1080);
+        assert_eq!(mode.vrefresh, 60);
+        assert_eq!(mode.clock, 148_500);
+        assert_eq!(mode.name, "1920x1080@60");
+        assert_eq!(mode.htotal, 2200);
+        assert_eq!(mode.vtotal, 1125);
+    }
+
+    #[test]
+    fn from_edid_synthetic_edid_too_short_returns_empty() {
+        let edid = super::connector::synthetic_edid();
+        assert!(edid.len() < 128, "synthetic EDID is shorter than 128 bytes");
+        let modes = ModeInfo::from_edid(&edid);
+        assert!(modes.is_empty(), "EDID shorter than 128 bytes should produce no modes");
+    }
+
+    #[test]
+    fn from_edid_empty_input_returns_empty() {
+        let modes = ModeInfo::from_edid(&[]);
+        assert!(modes.is_empty());
+    }
+
+    #[test]
+    fn from_edid_short_input_returns_empty() {
+        let modes = ModeInfo::from_edid(&[0u8; 64]);
+        assert!(modes.is_empty());
+    }
+
+    #[test]
+    fn from_edid_invalid_header_returns_empty() {
+        let mut data = vec![0u8; 128];
+        data[0] = 0x01;
+        let modes = ModeInfo::from_edid(&data);
+        assert!(modes.is_empty());
+    }
+
+    #[test]
+    fn from_edid_parsed_modes_have_nonzero_dimensions() {
+        let edid = super::connector::synthetic_edid();
+        let modes = ModeInfo::from_edid(&edid);
+        for mode in &modes {
+            assert_ne!(mode.hdisplay, 0, "hdisplay should not be zero");
+            assert_ne!(mode.vdisplay, 0, "vdisplay should not be zero");
+        }
+    }
+
+    #[test]
+    fn from_edid_parsed_modes_have_correct_name_format() {
+        let edid = super::connector::synthetic_edid();
+        let modes = ModeInfo::from_edid(&edid);
+        for mode in &modes {
+            let parts: Vec<&str> = mode.name.split('@').collect();
+            assert_eq!(parts.len(), 2, "name should contain exactly one '@': {}", mode.name);
+            let dims: Vec<&str> = parts[0].split('x').collect();
+            assert_eq!(dims.len(), 2, "name prefix should be WxH: {}", mode.name);
+            let w: u16 = dims[0].parse().expect("width should be numeric");
+            let h: u16 = dims[1].parse().expect("height should be numeric");
+            assert_eq!(w, mode.hdisplay);
+            assert_eq!(h, mode.vdisplay);
+            let refresh: u32 = parts[1].parse().expect("refresh should be numeric");
+            assert_eq!(refresh, mode.vrefresh);
+        }
+    }
+
+    #[test]
+    fn from_edid_with_valid_header_but_zero_pixel_clock_skips_descriptor() {
+        let mut data = vec![0u8; 128];
+        data[0] = 0x00;
+        data[1] = 0xFF;
+        data[2] = 0xFF;
+        data[3] = 0xFF;
+        data[4] = 0xFF;
+        data[5] = 0xFF;
+        data[6] = 0xFF;
+        data[7] = 0x00;
+        let modes = ModeInfo::from_edid(&data);
+        assert!(modes.is_empty());
+    }
+}
diff --git a/local/recipes/gpu/redox-drm/source/src/kms/plane.rs b/local/recipes/gpu/redox-drm/source/src/kms/plane.rs
index d9844717..ef4b31a6 100644
--- a/local/recipes/gpu/redox-drm/source/src/kms/plane.rs
+++ b/local/recipes/gpu/redox-drm/source/src/kms/plane.rs
@@ -40,3 +40,52 @@ impl Plane {
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn new_primary_initializes_correctly() {
+        let plane = Plane::new(7, PlaneKind::Primary);
+        assert_eq!(plane.id, 7);
+        assert_eq!(plane.kind, PlaneKind::Primary);
+        assert_eq!(plane.fb_handle, None);
+        assert_eq!(plane.crtc_id, None);
+    }
+
+    #[test]
+    fn new_cursor_initializes_correctly() {
+        let plane = Plane::new(3, PlaneKind::Cursor);
+        assert_eq!(plane.id, 3);
+        assert_eq!(plane.kind, PlaneKind::Cursor);
+        assert!(plane.fb_handle.is_none());
+        assert!(plane.crtc_id.is_none());
+    }
+
+    #[test]
+    fn attach_sets_crtc_id_and_fb_handle() {
+        let mut plane = Plane::new(1, PlaneKind::Primary);
+        let result = plane.attach(10, 20);
+
+        assert!(result.is_ok());
+        assert_eq!(plane.crtc_id, Some(10));
+        assert_eq!(plane.fb_handle, Some(20));
+    }
+
+    #[test]
+    fn attach_zero_fb_handle_returns_invalid_argument() {
+        let mut plane = Plane::new(1, PlaneKind::Primary);
+        let result = plane.attach(10, 0);
+
+        assert!(result.is_err());
+        match result.unwrap_err() {
+            DriverError::InvalidArgument(msg) => {
+                assert!(msg.contains("framebuffer"));
+            }
+            other => panic!("expected InvalidArgument, got {:?}", other),
+        }
+        assert_eq!(plane.crtc_id, None);
+        assert_eq!(plane.fb_handle, None);
+    }
+}
diff --git a/local/recipes/gpu/redox-drm/source/src/main.rs b/local/recipes/gpu/redox-drm/source/src/main.rs
index d44103b2..5f9a0af0 100644
--- a/local/recipes/gpu/redox-drm/source/src/main.rs
+++ b/local/recipes/gpu/redox-drm/source/src/main.rs
@@ -579,4 +579,54 @@ mod tests {
         assert!(!expectation.required);
         assert!(expectation.keys.is_empty());
     }
+
+    #[test]
+    fn mode_info_default_1080p_clock_matches_standard_cvt() {
+        use crate::kms::ModeInfo;
+        let mode = ModeInfo::default_1080p();
+        // Standard 1080p60 timing: 148.5 MHz pixel clock
+        assert_eq!(mode.clock, 148_500);
+        // Total pixels per frame = htotal * vtotal = 2200 * 1125 = 2_475_000
+        // Refresh = clock*1000 / total = 148_500_000 / 2_475_000 = 60
+        assert_eq!(mode.htotal as u32 * mode.vtotal as u32, 2_475_000_u32);
+    }
+
+    #[test]
+    fn mode_info_from_edid_rejects_short_edid() {
+        use crate::kms::connector::synthetic_edid;
+        use crate::kms::ModeInfo;
+        let edid = synthetic_edid();
+        assert!(edid.len() < 128);
+        let modes = ModeInfo::from_edid(&edid);
+        assert!(modes.is_empty());
+    }
+
+    #[test]
+    fn mode_info_from_edid_parses_valid_128byte_edid() {
+        use crate::kms::ModeInfo;
+        let mut edid = vec![0u8; 128];
+        edid[0] = 0x00;
+        edid[1] = 0xFF;
+        edid[2] = 0xFF;
+        edid[3] = 0xFF;
+        edid[4] = 0xFF;
+        edid[5] = 0xFF;
+        edid[6] = 0xFF;
+        edid[7] = 0x00;
+        let modes = ModeInfo::from_edid(&edid);
+        assert!(modes.is_empty(), "all-zero descriptors should produce no modes");
+    }
+
+    #[test]
+    fn mode_info_from_edid_name_format_is_width_x_height_at_refresh() {
+        use crate::kms::connector::synthetic_edid;
+        use crate::kms::ModeInfo;
+        let edid = synthetic_edid();
+        let modes = ModeInfo::from_edid(&edid);
+        for mode in &modes {
+            // Verify the canonical format: "WxH@refresh"
+            let expected = format!("{}x{}@{}", mode.hdisplay, mode.vdisplay, mode.vrefresh);
+            assert_eq!(mode.name, expected);
+        }
+    }
 }