diff --git a/engine/src/flutter/ci/analyze.sh b/engine/src/flutter/ci/analyze.sh
index bbacb876353..f04610f07ff 100755
--- a/engine/src/flutter/ci/analyze.sh
+++ b/engine/src/flutter/ci/analyze.sh
@@ -59,6 +59,7 @@ function analyze() (
 )
 
 echo "Analyzing dart:ui library..."
+autoninja -C "$SRC_DIR/out/host_debug_unopt" generate_dart_ui
 analyze \
   --options "$FLUTTER_DIR/analysis_options.yaml" \
   "$SRC_DIR/out/host_debug_unopt/gen/sky/bindings/dart_ui/ui.dart"
@@ -106,6 +107,8 @@ analyze \
   "$FLUTTER_DIR/testing/smoke_test_failure"
 
 echo "Analyzing testing/dart..."
+"$FLUTTER_DIR/tools/gn" --unoptimized
+autoninja -C "$SRC_DIR/out/host_debug_unopt" sky_engine sky_services
 (cd "$FLUTTER_DIR/testing/dart" && "$PUB" get --offline)
 analyze \
   --packages="$FLUTTER_DIR/testing/dart/.dart_tool/package_config.json" \
diff --git a/engine/src/flutter/testing/run_tests.py b/engine/src/flutter/testing/run_tests.py
index c8ee5d0a525..cb3bc7a17e4 100755
--- a/engine/src/flutter/testing/run_tests.py
+++ b/engine/src/flutter/testing/run_tests.py
@@ -283,19 +283,89 @@ def RunDartTest(build_dir, test_packages, dart_file, verbose_dart_snapshot, mult
 
 def EnsureDebugUnoptSkyPackagesAreBuilt():
   variant_out_dir = os.path.join(out_dir, 'host_debug_unopt')
-  assert os.path.exists(variant_out_dir), "%s doesn't exist. Run GN to generate the directory first" % variant_out_dir
+
+  ninja_command = [
+    'ninja',
+    '-C',
+    variant_out_dir,
+    'flutter/sky/packages'
+  ]
+
+  # Attempt running Ninja if the out directory exists.
+  # We don't want to blow away any custom GN args the caller may have already set.
+  if os.path.exists(variant_out_dir):
+    RunCmd(ninja_command, cwd=buildroot_dir)
+    return
+
+  gn_command = [
+    os.path.join(buildroot_dir, 'flutter', 'tools', 'gn'),
+    '--runtime-mode',
+    'debug',
+    '--unopt',
+    '--no-lto',
+  ]
+
+  RunCmd(gn_command, cwd=buildroot_dir)
+  RunCmd(ninja_command, cwd=buildroot_dir)
 
 
 def EnsureJavaTestsAreBuilt(android_out_dir):
   """Builds the engine variant and the test jar containing the JUnit tests"""
-  tmp_out_dir = os.path.join(out_dir, android_out_dir)
-  assert os.path.exists(tmp_out_dir), "%s doesn't exist. Run GN to generate the directory first" % android_out_dir
+  ninja_command = [
+    'autoninja',
+    '-C',
+    android_out_dir,
+    'flutter/shell/platform/android:robolectric_tests'
+  ]
+
+  # Attempt running Ninja if the out directory exists.
+  # We don't want to blow away any custom GN args the caller may have already set.
+  if os.path.exists(android_out_dir):
+    RunCmd(ninja_command, cwd=buildroot_dir)
+    return
+
+  assert android_out_dir != "out/android_debug_unopt", "%s doesn't exist. Run GN to generate the directory first" % android_out_dir
+
+  # Otherwise prepare the directory first, then build the test.
+  gn_command = [
+    os.path.join(buildroot_dir, 'flutter', 'tools', 'gn'),
+    '--android',
+    '--unoptimized',
+    '--runtime-mode=debug',
+    '--no-lto',
+  ]
+  RunCmd(gn_command, cwd=buildroot_dir)
+  RunCmd(ninja_command, cwd=buildroot_dir)
 
 
 def EnsureIosTestsAreBuilt(ios_out_dir):
   """Builds the engine variant and the test dylib containing the XCTests"""
-  tmp_out_dir = os.path.join(out_dir, ios_out_dir)
-  assert os.path.exists(tmp_out_dir), "%s doesn't exist. Run GN to generate the directory first" % ios_out_dir
+  ninja_command = [
+    'autoninja',
+    '-C',
+    ios_out_dir,
+    'ios_test_flutter'
+  ]
+
+  # Attempt running Ninja if the out directory exists.
+  # We don't want to blow away any custom GN args the caller may have already set.
+  if os.path.exists(ios_out_dir):
+    RunCmd(ninja_command, cwd=buildroot_dir)
+    return
+
+  assert ios_out_dir != "out/ios_debug_sim_unopt", "%s doesn't exist. Run GN to generate the directory first" % ios_out_dir
+
+  # Otherwise prepare the directory first, then build the test.
+  gn_command = [
+    os.path.join(buildroot_dir, 'flutter', 'tools', 'gn'),
+    '--ios',
+    '--unoptimized',
+    '--runtime-mode=debug',
+    '--no-lto',
+    '--simulator'
+  ]
+  RunCmd(gn_command, cwd=buildroot_dir)
+  RunCmd(ninja_command, cwd=buildroot_dir)
 
 
 def AssertExpectedJavaVersion():