diff --git a/apex/testing.go b/apex/testing.go
index e662cad..926125f 100644
--- a/apex/testing.go
+++ b/apex/testing.go
@@ -19,4 +19,11 @@
 var PrepareForTestWithApexBuildComponents = android.GroupFixturePreparers(
 	android.FixtureRegisterWithContext(registerApexBuildComponents),
 	android.FixtureRegisterWithContext(registerApexKeyBuildComponents),
+	// Additional files needed in tests that disallow non-existent source files.
+	// This includes files that are needed by all, or at least most, instances of an apex module type.
+	android.MockFS{
+		// Needed by apex.
+		"system/core/rootdir/etc/public.libraries.android.txt": nil,
+		"build/soong/scripts/gen_ndk_backedby_apex.sh":         nil,
+	}.AddToFixture(),
 )
diff --git a/cc/cc_test.go b/cc/cc_test.go
index 7196615..8b3a6bd 100644
--- a/cc/cc_test.go
+++ b/cc/cc_test.go
@@ -166,6 +166,15 @@
 	recoveryVariant = "android_recovery_arm64_armv8-a_shared"
 )
 
+// Test that the PrepareForTestWithCcDefaultModules provides all the files that it uses by
+// running it in a fixture that requires all source files to exist.
+func TestPrepareForTestWithCcDefaultModules(t *testing.T) {
+	android.GroupFixturePreparers(
+		PrepareForTestWithCcDefaultModules,
+		android.PrepareForTestDisallowNonExistentPaths,
+	).RunTest(t)
+}
+
 func TestFuchsiaDeps(t *testing.T) {
 	t.Helper()
 
diff --git a/cc/testing.go b/cc/testing.go
index d8adc61..6e35655 100644
--- a/cc/testing.go
+++ b/cc/testing.go
@@ -619,11 +619,26 @@
 
 		RegisterVndkLibraryTxtTypes(ctx)
 	}),
+
+	// Additional files needed in tests that disallow non-existent source files.
+	// This includes files that are needed by all, or at least most, instances of a cc module type.
+	android.MockFS{
+		// Needed for ndk_prebuilt_(shared|static)_stl.
+		"prebuilts/ndk/current/sources/cxx-stl/llvm-libc++/libs": nil,
+	}.AddToFixture(),
 )
 
 // Preparer that will define default cc modules, e.g. standard prebuilt modules.
 var PrepareForTestWithCcDefaultModules = android.GroupFixturePreparers(
 	PrepareForTestWithCcBuildComponents,
+
+	// Additional files needed in tests that disallow non-existent source.
+	android.MockFS{
+		"defaults/cc/common/libc.map.txt":  nil,
+		"defaults/cc/common/libdl.map.txt": nil,
+		"defaults/cc/common/libm.map.txt":  nil,
+	}.AddToFixture(),
+
 	// Place the default cc test modules that are common to all platforms in a location that will not
 	// conflict with default test modules defined by other packages.
 	android.FixtureAddTextFile(DefaultCcCommonTestModulesDir+"Android.bp", commonDefaultModules()),
diff --git a/sdk/cc_sdk_test.go b/sdk/cc_sdk_test.go
index 6c02bf7..a886a18 100644
--- a/sdk/cc_sdk_test.go
+++ b/sdk/cc_sdk_test.go
@@ -486,6 +486,9 @@
 		}
 	`)
 
+	// TODO(b/183322862): Remove this and fix the issue.
+	errorHandler := android.FixtureExpectsAtLeastOneErrorMatchingPattern(`module source path "snapshot/include_gen/generated_foo/gen/protos" does not exist`)
+
 	CheckSnapshot(t, result, "mysdk", "",
 		checkUnversionedAndroidBpContents(`
 // This is auto-generated. DO NOT EDIT.
@@ -518,6 +521,9 @@
 .intermediates/mynativelib/android_arm64_armv8-a_shared/mynativelib.so -> arm64/lib/mynativelib.so
 .intermediates/mynativelib/android_arm_armv7-a-neon_shared/mynativelib.so -> arm/lib/mynativelib.so
 `),
+		snapshotTestErrorHandler(checkSnapshotWithoutSource, errorHandler),
+		snapshotTestErrorHandler(checkSnapshotWithSourcePreferred, errorHandler),
+		snapshotTestErrorHandler(checkSnapshotPreferredWithSource, errorHandler),
 	)
 }
 
diff --git a/sdk/java_sdk_test.go b/sdk/java_sdk_test.go
index 6f78ded..2bc248d 100644
--- a/sdk/java_sdk_test.go
+++ b/sdk/java_sdk_test.go
@@ -24,6 +24,16 @@
 var prepareForSdkTestWithJava = android.GroupFixturePreparers(
 	java.PrepareForTestWithJavaBuildComponents,
 	PrepareForTestWithSdkBuildComponents,
+
+	// Ensure that all source paths are provided. This helps ensure that the snapshot generation is
+	// consistent and all files referenced from the snapshot's Android.bp file have actually been
+	// copied into the snapshot.
+	android.PrepareForTestDisallowNonExistentPaths,
+
+	// Files needs by most of the tests.
+	android.MockFS{
+		"Test.java": nil,
+	}.AddToFixture(),
 )
 
 var prepareForSdkTestWithJavaSdkLibrary = android.GroupFixturePreparers(
@@ -339,6 +349,7 @@
 	result := android.GroupFixturePreparers(
 		prepareForSdkTestWithJava,
 		android.FixtureAddFile("aidl/foo/bar/Test.aidl", nil),
+		android.FixtureAddFile("resource.txt", nil),
 	).RunTestWithBp(t, `
 		module_exports {
 			name: "myexports",
@@ -394,7 +405,11 @@
 }
 
 func TestSnapshotWithJavaBootLibrary(t *testing.T) {
-	result := android.GroupFixturePreparers(prepareForSdkTestWithJava).RunTestWithBp(t, `
+	result := android.GroupFixturePreparers(
+		prepareForSdkTestWithJava,
+		android.FixtureAddFile("aidl", nil),
+		android.FixtureAddFile("resource.txt", nil),
+	).RunTestWithBp(t, `
 		module_exports {
 			name: "myexports",
 			java_boot_libs: ["myjavalib"],
@@ -1539,7 +1554,10 @@
 }
 
 func TestSnapshotWithJavaSdkLibrary_DoctagFiles(t *testing.T) {
-	result := android.GroupFixturePreparers(prepareForSdkTestWithJavaSdkLibrary).RunTestWithBp(t, `
+	result := android.GroupFixturePreparers(
+		prepareForSdkTestWithJavaSdkLibrary,
+		android.FixtureAddFile("docs/known_doctags", nil),
+	).RunTestWithBp(t, `
 		sdk {
 			name: "mysdk",
 			java_sdk_libs: ["myjavalib"],
diff --git a/sdk/testing.go b/sdk/testing.go
index f253814..44970f7 100644
--- a/sdk/testing.go
+++ b/sdk/testing.go
@@ -48,10 +48,10 @@
 		"system/sepolicy/apex/myapex-file_contexts":    nil,
 		"system/sepolicy/apex/myapex2-file_contexts":   nil,
 		"system/sepolicy/apex/mysdkapex-file_contexts": nil,
-		"myapex.avbpubkey":                             nil,
-		"myapex.pem":                                   nil,
-		"myapex.x509.pem":                              nil,
-		"myapex.pk8":                                   nil,
+		"sdk/tests/myapex.avbpubkey":                   nil,
+		"sdk/tests/myapex.pem":                         nil,
+		"sdk/tests/myapex.x509.pem":                    nil,
+		"sdk/tests/myapex.pk8":                         nil,
 	}),
 )
 
@@ -80,6 +80,12 @@
 			{android.Windows, android.Arch{ArchType: android.X86_64}, android.NativeBridgeDisabled, "", "", true},
 		}
 	}),
+
+	// Make sure that every test provides all the source files.
+	android.PrepareForTestDisallowNonExistentPaths,
+	android.MockFS{
+		"Test.java": nil,
+	}.AddToFixture(),
 )
 
 var PrepareForTestWithSdkBuildComponents = android.GroupFixturePreparers(