Add Gstreamer check framework as unit tests for gvawatermark

[walidbarakat]

Description

add gvawatermark property and lifecycle unit tests

• Add 20 GStreamer Check tests for gvawatermarkimpl and gvawatermark (bin)
  covering element instantiation, default property values (device, obb,
  displ-avgfps, displ-cfg), set/get round-trips, NULL<->READY state
  transitions, and bin-to-impl property forwarding.

• Not tested: READY->PAUSED->PLAYING transitions (require negotiated caps),
  dynamic property changes during PLAYING state, property change notifications.

add gvawatermark caps negotiation and error path tests

• Add ~12 GStreamer Check tests using data-driven loop tests for caps
  negotiation (BGR, NV12, BGRA, RGBA, BGRx, I420), buffer passthrough
  identity (no metadata = no pixel change), resolution variants (64x48,
  1920x1080), and error paths (GPU+system-memory incompatibility,
  unsupported device name "FPGA").

• Not tested: VAAPI/DMA/D3D11 memory caps (require VA hardware), rejected
  pixel formats, caps renegotiation mid-stream.

add gvawatermark display config parsing and behavioral tests

• Add ~20 GStreamer Check tests for displ-cfg acceptance (all 10 config
  keys), behavioral verification (show-labels toggles text rendering,
  thickness scales pixel count, show-roi/hide-roi filter ROIs), edge
  cases (show-roi+hide-roi conflict where show-roi wins, invalid config
  value triggers pipeline error, multiple ROIs produce more pixels), and
  a design-revealing test (show-labels=false silently disables show-roi
  parsing due to nesting in parse_displ_config).

• Not tested: font-scale/font-type/draw-txt-bg/text-x/text-y pixel-level
  behavioral verification, tensor-driven rendering (landmarks, masks,
  keypoints, OBB), displ-avgfps integration, VA/GPU render path.

Checklist:

• I agree to use the MIT license for my code changes.
• I have not introduced any 3rd party components incompatible with MIT.
• I have not included any company confidential information, trade secret, password or security token.
• I have performed a self-review of my code.

[Copilot]

Pull request overview

This PR adds a new GStreamer Check–based unit test suite for gvawatermarkimpl and the gvawatermark bin, covering property defaults/set-get, basic state transitions, caps negotiation, buffer passthrough behavior, display-config parsing/acceptance, and several display-config behavioral/error-path cases.

Changes:

• Add new gvawatermarkimpl caps negotiation + passthrough + error-path tests.
• Add new display-config parsing/acceptance + behavioral tests (ROI filtering, thickness impact, show-labels behavior).
• Add new property/default/state tests for gvawatermarkimpl and the gvawatermark bin, plus CMake wiring to build/run the new tests.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
tests/unit_tests/check/elements/watermark/test_watermark/test_watermark_config.cpp	New display-config acceptance/behavior/error tests for gvawatermarkimpl.
tests/unit_tests/check/elements/watermark/test_watermark/test_watermark_caps.cpp	New caps negotiation, passthrough identity, resolution variants, and error-path tests.
tests/unit_tests/check/elements/watermark/test_watermark/CMakeLists.txt	Builds/runs the new watermark config + caps test executables.
tests/unit_tests/check/elements/watermark/test_properties/test_watermark_properties.cpp	New instantiation/defaults/set-get/state tests for impl + bin wrapper.
tests/unit_tests/check/elements/watermark/test_properties/CMakeLists.txt	Builds/runs the new watermark properties test executable.
tests/unit_tests/check/elements/watermark/CMakeLists.txt	Adds subdirectories for watermark tests.
tests/unit_tests/check/elements/CMakeLists.txt	Registers the new watermark/ tests in the elements test tree.

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[Copilot]

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

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[Copilot]

make_src_template/make_sink_template build a GstStaticPadTemplate using GST_STATIC_CAPS(caps_str) where caps_str is a const char* variable. GST_STATIC_CAPS is intended for string literals/char arrays (it relies on compile-time sizing); passing a pointer can produce an incorrect caps string length and lead to truncated/invalid caps during pad setup. Consider defining one GstStaticPadTemplate per format at file scope, or constructing the GstStaticCaps fields manually with strlen(caps_str) so the stored length is correct.

Suggested change

	* The caps_string must be a string literal or static storage (GstStaticPadTemplate
	* stores the pointer, not a copy).
	*/
	static GstStaticPadTemplate make_src_template(const char *caps_str) {
	GstStaticPadTemplate t = GST_STATIC_PAD_TEMPLATE("src", GST_PAD_SRC, GST_PAD_ALWAYS, GST_STATIC_CAPS(caps_str));
	return t;
	}
	static GstStaticPadTemplate make_sink_template(const char *caps_str) {
	GstStaticPadTemplate t = GST_STATIC_PAD_TEMPLATE("sink", GST_PAD_SINK, GST_PAD_ALWAYS, GST_STATIC_CAPS(caps_str));
	* Avoid GST_STATIC_CAPS(caps_str) here because caps_str is a function parameter,
	* not a direct literal/array expression for static macro initialization.
	*/
	static GstStaticPadTemplate make_src_template(const char *caps_str) {
	GstStaticPadTemplate t = {};
	t.name_template = "src";
	t.direction = GST_PAD_SRC;
	t.presence = GST_PAD_ALWAYS;
	t.static_caps.string = caps_str;
	t.static_caps.caps = NULL;
	return t;
	}
	static GstStaticPadTemplate make_sink_template(const char *caps_str) {
	GstStaticPadTemplate t = {};
	t.name_template = "sink";
	t.direction = GST_PAD_SINK;
	t.presence = GST_PAD_ALWAYS;
	t.static_caps.string = caps_str;
	t.static_caps.caps = NULL;