Add run_tests.sh to ffmpeg

projects/ffmpeg/Dockerfile

@@ -41,4 +41,4 @@ RUN git clone --depth 1 https://gitlab.xiph.org/xiph/theora.git
 RUN git clone --depth 1 https://gitlab.xiph.org/xiph/vorbis.git
 RUN git clone --depth 1 https://gitlab.gnome.org/GNOME/libxml2.git
 
-COPY build.sh replay_build.sh group_seed_corpus.py $SRC/
+COPY build.sh replay_build.sh run_tests.sh group_seed_corpus.py $SRC/

projects/ffmpeg/run_tests.sh

@@ -0,0 +1,68 @@
+#!/bin/bash
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+################################################################################
+
+# Usage: bash run_test.sh 
+# Runs all tests (same as 'make fate') and compiles if not compiled.
+
+set -e # Exit immediately if any command fails
+
+FFMPEG_SRC_DIR="/src/ffmpeg"
+OUT_DIR="${OUT:-/out}"
+
+# Executable fuzzer implies built.
+if [ ! -d "$OUT_DIR" ]; then
+  # Output directory does not exist.
+  # This implies no build has occurred or populated this directory.
+  IS_LIKELY_BUILT=0
+else
+  if [ -z "$(ls -A "$OUT_DIR" 2>/dev/null)" ]; then
+    # Output directory exists but is empty.
+    # This implies no build has populated this directory yet.
+    IS_LIKELY_BUILT=0
+  else
+    # Check specifically for executable files within OUT_DIR or its immediate subdirectories.
+    first_executable=$(find "$OUT_DIR" -maxdepth 2 -type f -executable -print -quit 2>/dev/null)
+
+    if [ -n "$first_executable" ]; then
+      # Found executable file(s) in the output directory.
+      # This suggests a build has already occurred.
+      IS_LIKELY_BUILT=1
+
+    else
+      # $OUT is not empty, but no executables found. Could be intermediate files, logs, corpus, etc.
+      IS_LIKELY_BUILT=0
+    fi
+  fi
+fi
+
+
+if [ "$IS_LIKELY_BUILT" -eq 0 ]; then
+    echo "==> Project is not likely built. Building..."
+    bash build.sh # TODO(carlolemos): Check if we get to the same state of
+    # us-central1-docker.pkg.dev/oss-fuzz/oss-fuzz-gen/ffmpeg-ofg-cached-address
+    make -j$(nproc)
+
+    echo "==> Build finished."
+fi
+
+echo "==> Changing to FFmpeg source directory: $FFMPEG_SRC_DIR"
+cd "$FFMPEG_SRC_DIR"
+
+echo "==> Running all FATE tests..."
+make fate
+
+echo "==> Test run finished successfully."