Generate FakeFeatureFlagsImpl in test mode

Before FeatureFlagsImpl will be used as a fake for testing. This change
adds new class FakeFeatureFlagsImpl. The FeatureFlagsImpl will keep the
same as production. FakeFeatureFlagsImpl can be used as fake for
testing.

FakeFeatureFlagsImpl, and FeatureFlagsImpl will be generated in both
test and prod mode. In test mode FeatureFlagsImpl will just be a stub,
and in prod mode FakeFeatureFlagsImpl will just be a stub.

Bug: 280833463
Test: atest aconfig.test
Change-Id: I11c1e716a9ea00d55600e5e9d5fb6442420762e6
diff --git a/tools/aconfig/src/codegen_java.rs b/tools/aconfig/src/codegen_java.rs
index 8ab6ffa..a117370 100644
--- a/tools/aconfig/src/codegen_java.rs
+++ b/tools/aconfig/src/codegen_java.rs
@@ -47,9 +47,13 @@
         "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 @@
         }
     "#;
 
+    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 @@
             + 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 @@
         "#;
         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 @@
         .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 @@
                 );
         }
         "#;
+
         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 0000000..db35d28
--- /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 082d476..ba86ce5 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 c244b15..012eba6 100644
--- a/tools/aconfig/templates/Flags.java.template
+++ b/tools/aconfig/templates/Flags.java.template
@@ -10,11 +10,11 @@
     }
 {{ 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}}