add more tests

engine/batching_test.odin

@@ -0,0 +1,64 @@
+package engine
+
+import "core:testing"
+import sdl "vendor:sdl3"
+
+fake_tex :: proc(id: uintptr) -> ^sdl.GPUTexture {
+	return cast(^sdl.GPUTexture)id
+}
+
+@(test)
+texture_run_len_empty_or_oob :: proc(t: ^testing.T) {
+	testing.expect_value(t, texture_run_len(nil, 0), 0)
+	list := []Queued_Sprite{}
+	testing.expect_value(t, texture_run_len(list, 0), 0)
+	list = make([]Queued_Sprite, 1)
+	defer delete(list)
+	list[0] = {texture = fake_tex(1)}
+	testing.expect_value(t, texture_run_len(list, -1), 0)
+	testing.expect_value(t, texture_run_len(list, 1), 0)
+}
+
+@(test)
+texture_run_len_single :: proc(t: ^testing.T) {
+	list := make([]Queued_Sprite, 1)
+	defer delete(list)
+	list[0] = {texture = fake_tex(1)}
+	testing.expect_value(t, texture_run_len(list, 0), 1)
+}
+
+@(test)
+texture_run_len_same_texture :: proc(t: ^testing.T) {
+	tex := fake_tex(1)
+	list := make([]Queued_Sprite, 3)
+	defer delete(list)
+	list[0] = {texture = tex}
+	list[1] = {texture = tex}
+	list[2] = {texture = tex}
+	testing.expect_value(t, texture_run_len(list, 0), 3)
+}
+
+@(test)
+texture_run_len_breaks_on_change :: proc(t: ^testing.T) {
+	a := fake_tex(1)
+	b := fake_tex(2)
+	list := make([]Queued_Sprite, 3)
+	defer delete(list)
+	list[0] = {texture = a}
+	list[1] = {texture = a}
+	list[2] = {texture = b}
+	testing.expect_value(t, texture_run_len(list, 0), 2)
+	testing.expect_value(t, texture_run_len(list, 2), 1)
+}
+
+@(test)
+texture_run_len_all_different :: proc(t: ^testing.T) {
+	list := make([]Queued_Sprite, 3)
+	defer delete(list)
+	list[0] = {texture = fake_tex(1)}
+	list[1] = {texture = fake_tex(2)}
+	list[2] = {texture = fake_tex(3)}
+	testing.expect_value(t, texture_run_len(list, 0), 1)
+	testing.expect_value(t, texture_run_len(list, 1), 1)
+	testing.expect_value(t, texture_run_len(list, 2), 1)
+}