Label prefixing in FT calculator (#804)

Author: gthea

src/main/java/io/split/android/client/fallback/FallbackTreatment.java

@@ -5,32 +5,30 @@
 
 import java.util.Objects;
 
-import io.split.android.grammar.Treatments;
-
 /**
  * Represents the fallback treatment, with an optional config and a fixed label.
  */
 public final class FallbackTreatment {
 
-    private static final String LABEL_PREFIX = "fallback - ";
-
-    /**
-     * Default fallback representing "control" treatment with no config.
-     */
-    public static final FallbackTreatment CONTROL = new FallbackTreatment(Treatments.CONTROL);
-
     @NonNull
     private final String mTreatment;
     @Nullable
     private final String mConfig;
+    @Nullable
+    private final String mLabel;
 
     public FallbackTreatment(@NonNull String treatment) {
         this(treatment, null);
     }
 
     public FallbackTreatment(@NonNull String treatment, @Nullable String config) {
+        this(treatment, config, null);
+    }
+
+    FallbackTreatment(@NonNull String treatment, @Nullable String config, @Nullable String label) {
         mTreatment = treatment;
         mConfig = config;
+        mLabel = label;
     }
 
     public String getTreatment() {
@@ -42,8 +40,13 @@ public String getConfig() {
         return mConfig;
     }
 
-    public String getLabelPrefix() {
-        return LABEL_PREFIX;
+    @Nullable
+    public String getLabel() {
+        return mLabel;
+    }
+
+    FallbackTreatment copyWithLabel(String label) {
+        return new FallbackTreatment(mTreatment, mConfig, label);
     }
 
     @Override
@@ -52,11 +55,12 @@ public boolean equals(Object o) {
         if (o == null || getClass() != o.getClass()) return false;
         FallbackTreatment that = (FallbackTreatment) o;
         return Objects.equals(mTreatment, that.mTreatment) &&
-                Objects.equals(mConfig, that.mConfig);
+                Objects.equals(mConfig, that.mConfig) &&
+                Objects.equals(mLabel, that.mLabel);
     }
 
     @Override
     public int hashCode() {
-        return Objects.hash(mTreatment, mConfig);
+        return Objects.hash(mTreatment, mConfig, mLabel);
     }
 }

src/main/java/io/split/android/client/fallback/FallbackTreatmentsCalculator.java

@@ -1,6 +1,7 @@
 package io.split.android.client.fallback;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 
 /**
  * Resolves a fallback treatment for a given flag name.
@@ -10,10 +11,19 @@ public interface FallbackTreatmentsCalculator {
 
     /**
      * Resolve a fallback for a given flag name.
-     *
      * @param flagName non-null flag name
-     * @return a fallback treatment if configured, otherwise "control"
+     * @return a fallback treatment with a null label, if configured; otherwise "control"
      */
     @NonNull
     FallbackTreatment resolve(@NonNull String flagName);
+
+    /**
+     * Resolve a fallback for a given flag name and label.
+     *
+     * @param flagName non-null flag name
+     * @param label    nullable label
+     * @return a fallback treatment if configured, with a prefixed label if provided; otherwise "control"
+     */
+    @NonNull
+    FallbackTreatment resolve(@NonNull String flagName, @Nullable String label);
 }

src/main/java/io/split/android/client/fallback/FallbackTreatmentsCalculatorImpl.java

@@ -1,11 +1,16 @@
 package io.split.android.client.fallback;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 
 import java.util.Map;
 
+import io.split.android.grammar.Treatments;
+
 public final class FallbackTreatmentsCalculatorImpl implements FallbackTreatmentsCalculator {
 
+    private static final String LABEL_PREFIX = "fallback - ";
+
     @NonNull
     private final FallbackConfiguration mConfig;
 
@@ -16,17 +21,32 @@ public FallbackTreatmentsCalculatorImpl(@NonNull FallbackConfiguration config) {
     @NonNull
     @Override
     public FallbackTreatment resolve(@NonNull String flagName) {
+        return resolve(flagName, null);
+    }
+
+    @NonNull
+    @Override
+    public FallbackTreatment resolve(@NonNull String flagName, @Nullable String label) {
         Map<String, FallbackTreatment> byFlag = mConfig.getByFlag();
         if (byFlag != null) {
             FallbackTreatment flagTreatment = byFlag.get(flagName);
             if (flagTreatment != null) {
-                return flagTreatment;
+                return flagTreatment.copyWithLabel(resolveLabel(label));
             }
         }
         FallbackTreatment global = mConfig.getGlobal();
         if (global != null) {
-            return global;
+            return global.copyWithLabel(resolveLabel(label));
         }
-        return FallbackTreatment.CONTROL;
+        return new FallbackTreatment(Treatments.CONTROL, null, label);
+    }
+
+    @Nullable
+    private static String resolveLabel(@Nullable String label) {
+        if (label == null) {
+            return null;
+        }
+
+        return LABEL_PREFIX + label;
     }
 }

src/test/java/io/split/android/client/fallback/FallbackTreatmentTest.java

@@ -8,30 +8,36 @@
 
 public class FallbackTreatmentTest {
 
-    private static final String FALLBACK_TREATMENT = "fallback - ";
-
     @Test
     public void constructorSetsFields() {
-        FallbackTreatment ft = new FallbackTreatment("off", "{\"k\":true}");
+        FallbackTreatment ft = new FallbackTreatment("off", "{\"k\":true}", "my label");
         assertEquals("off", ft.getTreatment());
         assertEquals("{\"k\":true}", ft.getConfig());
-        assertEquals(FALLBACK_TREATMENT, ft.getLabelPrefix());
+        assertEquals("my label", ft.getLabel());
     }
 
     @Test
     public void configCanBeNull() {
-        FallbackTreatment ft = new FallbackTreatment("off", null);
+        FallbackTreatment ft = new FallbackTreatment("off", null, "my label");
+        assertEquals("off", ft.getTreatment());
+        assertNull(ft.getConfig());
+        assertEquals("my label", ft.getLabel());
+    }
+
+    @Test
+    public void labelCanBeNull() {
+        FallbackTreatment ft = new FallbackTreatment("off", null, null);
         assertEquals("off", ft.getTreatment());
         assertNull(ft.getConfig());
-        assertEquals(FALLBACK_TREATMENT, ft.getLabelPrefix());
+        assertNull(ft.getLabel());
     }
 
     @Test
-    public void convenienceConstructorSetsNullConfig() {
+    public void convenienceConstructorSetsNullConfigAndLabel() {
         FallbackTreatment ft = new FallbackTreatment("off");
         assertEquals("off", ft.getTreatment());
         assertNull(ft.getConfig());
-        assertEquals(FALLBACK_TREATMENT, ft.getLabelPrefix());
+        assertNull(ft.getLabel());
     }
 
     @Test

src/test/java/io/split/android/client/fallback/FallbackTreatmentsCalculatorTest.java

@@ -2,13 +2,16 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
 
 import org.junit.Test;
 
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 
+import io.split.android.client.TreatmentLabels;
+
 public class FallbackTreatmentsCalculatorTest {
 
     @Test
@@ -72,7 +75,7 @@ public void returnsControlWhenNoFallbackConfigured() {
         FallbackTreatment resolved = calculator.resolve("nope");
 
         assertNotNull(resolved);
-        assertEquals(FallbackTreatment.CONTROL, resolved);
+        assertEquals(new FallbackTreatment("control", null, null), resolved);
     }
 
     @Test
@@ -91,4 +94,32 @@ public void nonexistentFlagFallsBackToGlobal() {
         assertNotNull(resolved);
         assertEquals(global, resolved);
     }
+
+    @Test
+    public void labelIsPrefixed() {
+        FallbackTreatment global = new FallbackTreatment("off");
+        FallbackConfiguration config = FallbackConfiguration.builder()
+                .global(global)
+                .build();
+
+        FallbackTreatmentsCalculator calculator = new FallbackTreatmentsCalculatorImpl(config);
+        FallbackTreatment resolved = calculator.resolve("flagA", TreatmentLabels.EXCEPTION);
+
+        assertNotNull(resolved);
+        assertEquals("fallback - exception", resolved.getLabel());
+    }
+
+    @Test
+    public void noLabelReturnsNull() {
+        FallbackTreatment global = new FallbackTreatment("off");
+        FallbackConfiguration config = FallbackConfiguration.builder()
+                .global(global)
+                .build();
+
+        FallbackTreatmentsCalculator calculator = new FallbackTreatmentsCalculatorImpl(config);
+        FallbackTreatment resolved = calculator.resolve("flagA", null);
+
+        assertNotNull(resolved);
+        assertNull(resolved.getLabel());
+    }
 }