feat(raster): IO abstraction with godal implementation; cgo Dockerfile

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

internal/raster/io_test.go

@@ -0,0 +1,61 @@
+package raster
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestWindows(t *testing.T) {
+	tests := []struct {
+		name       string
+		w, h, size int
+		want       []Window
+	}{
+		{
+			name: "10x10 size4 tiles into 9 windows",
+			w:    10, h: 10, size: 4,
+			want: []Window{
+				{X: 0, Y: 0, Width: 4, Height: 4},
+				{X: 4, Y: 0, Width: 4, Height: 4},
+				{X: 8, Y: 0, Width: 2, Height: 4},
+				{X: 0, Y: 4, Width: 4, Height: 4},
+				{X: 4, Y: 4, Width: 4, Height: 4},
+				{X: 8, Y: 4, Width: 2, Height: 4},
+				{X: 0, Y: 8, Width: 4, Height: 2},
+				{X: 4, Y: 8, Width: 4, Height: 2},
+				{X: 8, Y: 8, Width: 2, Height: 2},
+			},
+		},
+		{
+			name: "5x3 size8 fits in one window",
+			w:    5, h: 3, size: 8,
+			want: []Window{
+				{X: 0, Y: 0, Width: 5, Height: 3},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := Windows(tt.w, tt.h, tt.size)
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Fatalf("Windows(%d, %d, %d) = %+v, want %+v", tt.w, tt.h, tt.size, got, tt.want)
+			}
+			if len(got) > 0 {
+				last := got[len(got)-1]
+				wantLast := tt.want[len(tt.want)-1]
+				if last != wantLast {
+					t.Fatalf("last window = %+v, want %+v", last, wantLast)
+				}
+			}
+		})
+	}
+}
+
+func TestDefaultWriterOptions(t *testing.T) {
+	got := DefaultWriterOptions()
+	want := WriterOptions{NoData: -9999, TileSize: 512, Compression: "DEFLATE"}
+	if got != want {
+		t.Fatalf("DefaultWriterOptions() = %+v, want %+v", got, want)
+	}
+}