diff --git a/tools/aconfig/src/codegen_java.rs b/tools/aconfig/src/codegen_java.rs
index 8ab6ffa8f7..a11737034c 100644
--- a/tools/aconfig/src/codegen_java.rs
+++ b/tools/aconfig/src/codegen_java.rs
@@ -47,9 +47,13 @@ where
         "FeatureFlags.java",
         include_str!("../templates/FeatureFlags.java.template"),
     )?;
+    template.add_template(
+        "FakeFeatureFlagsImpl.java",
+        include_str!("../templates/FakeFeatureFlagsImpl.java.template"),
+    )?;
 
     let path: PathBuf = package.split('.').collect();
-    ["Flags.java", "FeatureFlagsImpl.java", "FeatureFlags.java"]
+    ["Flags.java", "FeatureFlags.java", "FeatureFlagsImpl.java", "FakeFeatureFlagsImpl.java"]
         .iter()
         .map(|file| {
             Ok(OutputFile {
@@ -143,6 +147,29 @@ mod tests {
         }
     "#;
 
+    const EXPECTED_METHOD_NOT_IMPL_COMMON_CONTENT: &str = r#"
+        @Override
+        public boolean disabledRo() {
+            throw new UnsupportedOperationException(
+                "Method is not implemented.");
+        }
+        @Override
+        public boolean disabledRw() {
+            throw new UnsupportedOperationException(
+                "Method is not implemented.");
+        }
+        @Override
+        public boolean enabledRo() {
+            throw new UnsupportedOperationException(
+                "Method is not implemented.");
+        }
+        @Override
+        public boolean enabledRw() {
+            throw new UnsupportedOperationException(
+                "Method is not implemented.");
+        }
+    "#;
+
     #[test]
     fn test_generate_java_code_production() {
         let parsed_flags = crate::test::parse_test_flags();
@@ -156,7 +183,15 @@ mod tests {
             + r#"
             private static FeatureFlags FEATURE_FLAGS = new FeatureFlagsImpl();
         }"#;
-        let expected_featureflagsimpl_content = r#"
+        let expect_fakefeatureflagsimpl_content = r#"
+        package com.android.aconfig.test;
+        public class FakeFeatureFlagsImpl implements FeatureFlags {"#
+            .to_owned()
+            + EXPECTED_METHOD_NOT_IMPL_COMMON_CONTENT
+            + r#"
+        }
+        "#;
+        let expect_featureflagsimpl_content = r#"
         package com.android.aconfig.test;
         import android.provider.DeviceConfig;
         public final class FeatureFlagsImpl implements FeatureFlags {
@@ -188,8 +223,12 @@ mod tests {
         "#;
         let mut file_set = HashMap::from([
             ("com/android/aconfig/test/Flags.java", expect_flags_content.as_str()),
-            ("com/android/aconfig/test/FeatureFlagsImpl.java", expected_featureflagsimpl_content),
+            ("com/android/aconfig/test/FeatureFlagsImpl.java", expect_featureflagsimpl_content),
             ("com/android/aconfig/test/FeatureFlags.java", EXPECTED_FEATUREFLAGS_CONTENT),
+            (
+                "com/android/aconfig/test/FakeFeatureFlagsImpl.java",
+                expect_fakefeatureflagsimpl_content.as_str(),
+            ),
         ]);
 
         for file in generated_files {
@@ -221,22 +260,30 @@ mod tests {
         .unwrap();
         let expect_flags_content = EXPECTED_FLAG_COMMON_CONTENT.to_string()
             + r#"
-            public static void setFeatureFlagsImpl(FeatureFlags featureFlags) {
+            public static void setFeatureFlags(FeatureFlags featureFlags) {
                 Flags.FEATURE_FLAGS = featureFlags;
             }
-            public static void unsetFeatureFlagsImpl() {
+            public static void unsetFeatureFlags() {
                 Flags.FEATURE_FLAGS = null;
             }
             private static FeatureFlags FEATURE_FLAGS;
         }
         "#;
-        let expected_featureflagsimpl_content = r#"
+        let expect_featureflagsimpl_content = r#"
+        package com.android.aconfig.test;
+        public final class FeatureFlagsImpl implements FeatureFlags {"#
+            .to_owned()
+            + EXPECTED_METHOD_NOT_IMPL_COMMON_CONTENT
+            + r#"
+        }
+        "#;
+        let expect_fakefeatureflagsimpl_content = r#"
         package com.android.aconfig.test;
         import static java.util.stream.Collectors.toMap;
         import java.util.HashMap;
         import java.util.Map;
         import java.util.stream.Stream;
-        public final class FeatureFlagsImpl implements FeatureFlags {
+        public class FakeFeatureFlagsImpl implements FeatureFlags {
             @Override
             public boolean disabledRo() {
                 return getFlag(Flags.FLAG_DISABLED_RO);
@@ -284,10 +331,18 @@ mod tests {
                 );
         }
         "#;
+
         let mut file_set = HashMap::from([
             ("com/android/aconfig/test/Flags.java", expect_flags_content.as_str()),
-            ("com/android/aconfig/test/FeatureFlagsImpl.java", expected_featureflagsimpl_content),
             ("com/android/aconfig/test/FeatureFlags.java", EXPECTED_FEATUREFLAGS_CONTENT),
+            (
+                "com/android/aconfig/test/FeatureFlagsImpl.java",
+                expect_featureflagsimpl_content.as_str(),
+            ),
+            (
+                "com/android/aconfig/test/FakeFeatureFlagsImpl.java",
+                expect_fakefeatureflagsimpl_content,
+            ),
         ]);
 
         for file in generated_files {
diff --git a/tools/aconfig/templates/FakeFeatureFlagsImpl.java.template b/tools/aconfig/templates/FakeFeatureFlagsImpl.java.template
new file mode 100644
index 0000000000..db35d28f68
--- /dev/null
+++ b/tools/aconfig/templates/FakeFeatureFlagsImpl.java.template
@@ -0,0 +1,59 @@
+package {package_name};
+{{ if is_test_mode }}
+import static java.util.stream.Collectors.toMap;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.stream.Stream;
+
+public class FakeFeatureFlagsImpl implements FeatureFlags \{
+{{ for item in class_elements}}
+    @Override
+    public boolean {item.method_name}() \{
+        return getFlag(Flags.FLAG_{item.flag_name_constant_suffix});
+    }
+{{ endfor}}
+    public void setFlag(String flagName, boolean value) \{
+        if (!this.mFlagMap.containsKey(flagName)) \{
+            throw new IllegalArgumentException("no such flag" + flagName);
+        }
+        this.mFlagMap.put(flagName, value);
+    }
+
+    public void resetAll() \{
+        for (Map.Entry entry : mFlagMap.entrySet()) \{
+            entry.setValue(null);
+        }
+    }
+
+    private boolean getFlag(String flagName) \{
+        Boolean value = this.mFlagMap.get(flagName);
+        if (value == null) \{
+            throw new IllegalArgumentException(flagName + " is not set");
+        }
+        return value;
+    }
+
+    private HashMap<String, Boolean> mFlagMap = Stream.of(
+            {{-for item in class_elements}}
+            Flags.FLAG_{item.flag_name_constant_suffix}{{ if not @last }},{{ endif }}
+            {{ -endfor }}
+        )
+        .collect(
+            HashMap::new,
+            (map, elem) -> map.put(elem, null),
+            HashMap::putAll
+        );
+}
+{{ else }}
+{#- Generate only stub if in prod mode #}
+public class FakeFeatureFlagsImpl implements FeatureFlags \{
+{{ for item in class_elements}}
+    @Override
+    public boolean {item.method_name}() \{
+        throw new UnsupportedOperationException(
+            "Method is not implemented.");
+    }
+{{ endfor}}
+}
+{{ endif }}
diff --git a/tools/aconfig/templates/FeatureFlagsImpl.java.template b/tools/aconfig/templates/FeatureFlagsImpl.java.template
index 082d476de5..ba86ce552c 100644
--- a/tools/aconfig/templates/FeatureFlagsImpl.java.template
+++ b/tools/aconfig/templates/FeatureFlagsImpl.java.template
@@ -1,65 +1,33 @@
 package {package_name};
-{{ -if is_test_mode }}
-import static java.util.stream.Collectors.toMap;
-
-import java.util.HashMap;
-import java.util.Map;
-import java.util.stream.Stream;
-{{ else}}
+{{ if not is_test_mode }}
 {{ if is_read_write- }}
 import android.provider.DeviceConfig;
-{{ -endif- }}
 {{ endif }}
 public final class FeatureFlagsImpl implements FeatureFlags \{
 {{ for item in class_elements}}
     @Override
     public boolean {item.method_name}() \{
-        {{ -if not is_test_mode- }}
-        {{ if item.is_read_write }}
+    {{ -if item.is_read_write }}
         return DeviceConfig.getBoolean(
             "{item.device_config_namespace}",
             "{item.device_config_flag}",
             {item.default_value}
         );
-        {{ -else }}
+    {{ else }}
         return {item.default_value};
-        {{ -endif- }}
-        {{ else }}
-        return getFlag(Flags.FLAG_{item.flag_name_constant_suffix});
-        {{ -endif }}
+    {{ endif- }}
     }
 {{ endfor- }}
-{{ if is_test_mode }}
-    public void setFlag(String flagName, boolean value) \{
-        if (!this.mFlagMap.containsKey(flagName)) \{
-            throw new IllegalArgumentException("no such flag" + flagName);
-        }
-        this.mFlagMap.put(flagName, value);
-    }
-
-    public void resetAll() \{
-        for (Map.Entry entry : mFlagMap.entrySet()) \{
-            entry.setValue(null);
-        }
-    }
-
-    private boolean getFlag(String flagName) \{
-        Boolean value = this.mFlagMap.get(flagName);
-        if (value == null) \{
-            throw new IllegalArgumentException(flagName + " is not set");
-        }
-        return value;
-    }
-
-    private HashMap<String, Boolean> mFlagMap = Stream.of(
-            {{-for item in class_elements}}
-            Flags.FLAG_{item.flag_name_constant_suffix}{{ if not @last }},{{ endif }}
-            {{ -endfor }}
-        )
-        .collect(
-            HashMap::new,
-            (map, elem) -> map.put(elem, null),
-            HashMap::putAll
-        );
-{{ -endif }}
 }
+{{ else }}
+{#- Generate only stub if in test mode #}
+public final class FeatureFlagsImpl implements FeatureFlags \{
+{{ for item in class_elements}}
+    @Override
+    public boolean {item.method_name}() \{
+        throw new UnsupportedOperationException(
+            "Method is not implemented.");
+    }
+{{ endfor- }}
+}
+{{ endif }}
diff --git a/tools/aconfig/templates/Flags.java.template b/tools/aconfig/templates/Flags.java.template
index c244b15156..012eba6660 100644
--- a/tools/aconfig/templates/Flags.java.template
+++ b/tools/aconfig/templates/Flags.java.template
@@ -10,11 +10,11 @@ public final class Flags \{
     }
 {{ endfor }}
 {{ -if is_test_mode }}
-    public static void setFeatureFlagsImpl(FeatureFlags featureFlags) \{
+    public static void setFeatureFlags(FeatureFlags featureFlags) \{
         Flags.FEATURE_FLAGS = featureFlags;
     }
 
-    public static void unsetFeatureFlagsImpl() \{
+    public static void unsetFeatureFlags() \{
         Flags.FEATURE_FLAGS = null;
     }
 {{ endif}}