[PATCH v2 3/3] oe-selftest: fitimage: Add test for signing U-Boot FIT image without SPL

[Jamin Lin <jamin_lin@aspeedtech.com>]

This adds a new selftest case `test_sign_uboot_fit_image_without_spl` to verify
that the build can correctly generate and sign a U-Boot FIT image in a scenario
where no SPL is used.

Background:
- Some boards build only the U-Boot proper FIT image and do not require an SPL.
- The signing flow must handle this case gracefully: generate the ITS, sign
  the FIT image, and skip signing/injecting a key into the SPL DTB.

What this test does:
1) Enables `UBOOT_FITIMAGE_ENABLE` and `SPL_SIGN_ENABLE` but explicitly sets
   `SPL_DTB_BINARY` to an empty string to indicate that no SPL is present.
2) Verifies that the U-Boot ITS and FIT image are built successfully.
3) Confirms that the generated ITS file includes signature metadata as requested.
4) Dumps the FIT image to ensure that the signature nodes exist.
5) Confirms that the log for `do_uboot_assemble_fitimage` shows the expected
   mkimage/mkimage_sign invocation.

This ensures that signing works correctly even when only the U-Boot proper is built,
which matches real-world configurations that do not require an SPL.

Signed-off-by: Jamin Lin <jamin_lin@aspeedtech.com>
---
 meta/lib/oeqa/selftest/cases/fitimage.py | 37 ++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/meta/lib/oeqa/selftest/cases/fitimage.py b/meta/lib/oeqa/selftest/cases/fitimage.py
index ca4724d1ae..3c40857747 100644
--- a/meta/lib/oeqa/selftest/cases/fitimage.py
+++ b/meta/lib/oeqa/selftest/cases/fitimage.py
@@ -1692,3 +1692,40 @@ FIT_SIGN_INDIVIDUAL = "1"
 
         # Just check the DTB of u-boot since there is no u-boot FIT image
         self._check_kernel_dtb(bb_vars)
+
+
+    def test_sign_uboot_fit_image_without_spl(self):
+        """
+        Summary:     Check if U-Boot FIT image and Image Tree Source (its) are
+                     created and signed correctly for the scenario where only
+                     the U-Boot proper fitImage is being created and signed
+                     (no SPL included).
+        Expected:    1) U-Boot its and FIT image are built successfully
+                     2) Scanning the its file indicates signing is enabled
+                        as requested by SPL_SIGN_ENABLE (using keys generated
+                        via UBOOT_FIT_GENERATE_KEYS)
+                     3) Dumping the FIT image indicates signature values
+                        are present
+                     4) Examination of the do_uboot_assemble_fitimage
+                     runfile/logfile indicate that UBOOT_MKIMAGE and
+                     UBOOT_MKIMAGE_SIGN are working as expected.
+        Product:     oe-core
+        Author:      Jamin Lin <jamin_lin@aspeedtech.com>
+        """
+        config = """
+# There's no U-boot defconfig with CONFIG_FIT_SIGNATURE yet, so we need at
+# least CONFIG_SPL_LOAD_FIT and CONFIG_SPL_OF_CONTROL set
+MACHINE = "qemuarm"
+UBOOT_MACHINE = "am57xx_evm_defconfig"
+# Enable creation and signing of the U-Boot fitImage (no SPL)
+UBOOT_FITIMAGE_ENABLE = "1"
+SPL_DTB_BINARY = ""
+SPL_SIGN_ENABLE = "1"
+SPL_SIGN_KEYNAME = "spl-oe-selftest"
+SPL_SIGN_KEYDIR = "${TOPDIR}/signing-keys"
+UBOOT_FIT_GENERATE_KEYS = "1"
+"""
+        self.write_config(config)
+        bb_vars = self._fit_get_bb_vars()
+        self._test_fitimage(bb_vars)
+
-- 
2.43.0