Rework Notification Sectioning

To create a notification section:
- Override Coordinator#getSection to return your desired NotifSection
- Ensure your new section is added in the correct order to
NotifCoordinators.mOrderedSections

Test: atest SystemUiTests
Change-Id: Ia3f83f4b662cdfb198981e94fba67f97eab767b8

9 files changed, 283 insertions, 88 deletions

diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/ListDumper.java b/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/ListDumper.java
index 9f21950e347d..eaa9d78c08f4 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/ListDumper.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/ListDumper.java
@@ -99,6 +99,13 @@ public class ListDumper {
                     .append(")");
         }
 
+        if (entry.mNotifSection != null) {
+            sb.append(" sectionIndex=")
+                    .append(entry.getSection())
+                    .append(" sectionName=")
+                    .append(entry.mNotifSection.getName());
+        }
+
         if (includeRecordKeeping) {
             NotificationEntry notifEntry = entry.getRepresentativeEntry();
             StringBuilder rksb = new StringBuilder();
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/ListEntry.java b/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/ListEntry.java
index dc68c4bdba78..56ad0e1df36f 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/ListEntry.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/ListEntry.java
@@ -18,6 +18,8 @@ package com.android.systemui.statusbar.notification.collection;
 
 import android.annotation.Nullable;
 
+import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.NotifSection;
+
 /**
  * Abstract superclass for top-level entries, i.e. things that can appear in the final notification
  * list shown to users. In practice, this means either GroupEntries or NotificationEntries.
@@ -27,7 +29,9 @@ public abstract class ListEntry {
 
     @Nullable private GroupEntry mParent;
     @Nullable private GroupEntry mPreviousParent;
-    private int mSection;
+    @Nullable NotifSection mNotifSection;
+
+    private int mSection = -1;
     int mFirstAddedIteration = -1;
 
     ListEntry(String key) {
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/NotifPipeline.java b/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/NotifPipeline.java
index 71245178a876..0377f57a7a9c 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/NotifPipeline.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/NotifPipeline.java
@@ -22,7 +22,7 @@ import com.android.systemui.statusbar.notification.collection.listbuilder.OnBefo
 import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.NotifComparator;
 import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.NotifFilter;
 import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.NotifPromoter;
-import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.SectionsProvider;
+import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.NotifSection;
 import com.android.systemui.statusbar.notification.collection.notifcollection.NotifCollectionListener;
 import com.android.systemui.statusbar.notification.collection.notifcollection.NotifLifetimeExtender;
 
@@ -48,7 +48,7 @@ import javax.inject.Singleton;
  *   GroupEntry. These groups are then transformed in order to remove children or completely split
  *   them apart. To participate, see {@link #addPromoter}.
  * - Sorted: All top-level notifications are sorted. To participate, see
- *   {@link #setSectionsProvider} and {@link #setComparators}
+ *   {@link #setSections} and {@link #setComparators}
  *
  * The exact order of all hooks is as follows:
  *  0. Collection listeners are fired ({@link #addCollectionListener}).
@@ -58,7 +58,7 @@ import javax.inject.Singleton;
  *  3. OnBeforeTransformGroupListeners are fired ({@link #addOnBeforeTransformGroupsListener})
  *  4. NotifPromoters are called on each notification with a parent ({@link #addPromoter})
  *  5. OnBeforeSortListeners are fired ({@link #addOnBeforeSortListener})
- *  6. SectionsProvider is called on each top-level entry in the list ({@link #setSectionsProvider})
+ *  6. Top-level entries are assigned sections by NotifSections ({@link #setSections})
  *  7. Top-level entries within the same section are sorted by NotifComparators
  *     ({@link #setComparators})
  *  8. Pre-render filters are fired on each notification ({@link #addPreRenderFilter})
@@ -142,14 +142,13 @@ public class NotifPipeline {
     }
 
     /**
-     * Assigns sections to each top-level entry, where a section is simply an integer. Sections are
-     * the primary metric by which top-level entries are sorted; NotifComparators are only consulted
-     * when two entries are in the same section. The pipeline doesn't assign any particular meaning
-     * to section IDs -- from it's perspective they're just numbers and it sorts them by a simple
-     * numerical comparison.
+     * Sections that are used to sort top-level entries.  If two entries have the same section,
+     * NotifComparators are consulted. Sections from this list are called in order for each
+     * notification passed through the pipeline. The first NotifSection to return true for
+     * {@link NotifSection#isInSection(ListEntry)} sets the entry as part of its Section.
      */
-    public void setSectionsProvider(SectionsProvider provider) {
-        mShadeListBuilder.setSectionsProvider(provider);
+    public void setSections(List<NotifSection> sections) {
+        mShadeListBuilder.setSections(sections);
     }
 
     /**
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/ShadeListBuilder.java b/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/ShadeListBuilder.java
index c19ce2730c61..97f8ec5f5bb7 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/ShadeListBuilder.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/ShadeListBuilder.java
@@ -30,6 +30,7 @@ import static com.android.systemui.statusbar.notification.collection.listbuilder
 import android.annotation.MainThread;
 import android.annotation.Nullable;
 import android.util.ArrayMap;
+import android.util.Pair;
 
 import com.android.systemui.DumpController;
 import com.android.systemui.Dumpable;
@@ -40,7 +41,7 @@ import com.android.systemui.statusbar.notification.collection.listbuilder.Pipeli
 import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.NotifComparator;
 import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.NotifFilter;
 import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.NotifPromoter;
-import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.SectionsProvider;
+import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.NotifSection;
 import com.android.systemui.statusbar.notification.collection.notifcollection.CollectionReadyForBuildListener;
 import com.android.systemui.statusbar.notification.logging.NotifEvent;
 import com.android.systemui.statusbar.notification.logging.NotifLog;
@@ -82,7 +83,7 @@ public class ShadeListBuilder implements Dumpable {
     private final List<NotifPromoter> mNotifPromoters = new ArrayList<>();
     private final List<NotifFilter> mNotifPreRenderFilters = new ArrayList<>();
     private final List<NotifComparator> mNotifComparators = new ArrayList<>();
-    private SectionsProvider mSectionsProvider = new DefaultSectionsProvider();
+    private final List<NotifSection> mNotifSections = new ArrayList<>();
 
     private final List<OnBeforeTransformGroupsListener> mOnBeforeTransformGroupsListeners =
             new ArrayList<>();
@@ -170,12 +171,15 @@ public class ShadeListBuilder implements Dumpable {
         promoter.setInvalidationListener(this::onPromoterInvalidated);
     }
 
-    void setSectionsProvider(SectionsProvider provider) {
+    void setSections(List<NotifSection> sections) {
         Assert.isMainThread();
         mPipelineState.requireState(STATE_IDLE);
 
-        mSectionsProvider = provider;
-        provider.setInvalidationListener(this::onSectionsProviderInvalidated);
+        mNotifSections.clear();
+        for (NotifSection section : sections) {
+            mNotifSections.add(section);
+            section.setInvalidationListener(this::onNotifSectionInvalidated);
+        }
     }
 
     void setComparators(List<NotifComparator> comparators) {
@@ -230,12 +234,12 @@ public class ShadeListBuilder implements Dumpable {
         rebuildListIfBefore(STATE_TRANSFORMING);
     }
 
-    private void onSectionsProviderInvalidated(SectionsProvider provider) {
+    private void onNotifSectionInvalidated(NotifSection section) {
         Assert.isMainThread();
 
-        mNotifLog.log(NotifEvent.SECTIONS_PROVIDER_INVALIDATED, String.format(
-                "Sections provider \"%s\" invalidated; pipeline state is %d",
-                provider.getName(),
+        mNotifLog.log(NotifEvent.SECTION_INVALIDATED, String.format(
+                "Section \"%s\" invalidated; pipeline state is %d",
+                section.getName(),
                 mPipelineState.getState()));
 
         rebuildListIfBefore(STATE_SORTING);
@@ -318,7 +322,7 @@ public class ShadeListBuilder implements Dumpable {
         sortList();
 
         // Step 6: Filter out entries after pre-group filtering, grouping, promoting and sorting
-        // Now filters can see grouping information to determine whether to filter or not
+        // Now filters can see grouping information to determine whether to filter or not.
         mPipelineState.incrementTo(STATE_PRE_RENDER_FILTERING);
         filterNotifs(mNotifList, mNewNotifList, mNotifPreRenderFilters);
         applyNewNotifList();
@@ -580,6 +584,8 @@ public class ShadeListBuilder implements Dumpable {
      * filtered out during any of the filtering steps.
      */
     private void annulAddition(ListEntry entry) {
+        entry.setSection(-1);
+        entry.mNotifSection = null;
         entry.setParent(null);
         if (entry.mFirstAddedIteration == mIterationCount) {
             entry.mFirstAddedIteration = -1;
@@ -589,11 +595,12 @@ public class ShadeListBuilder implements Dumpable {
     private void sortList() {
         // Assign sections to top-level elements and sort their children
         for (ListEntry entry : mNotifList) {
-            entry.setSection(mSectionsProvider.getSection(entry));
+            Pair<NotifSection, Integer> sectionWithIndex = applySections(entry);
             if (entry instanceof GroupEntry) {
                 GroupEntry parent = (GroupEntry) entry;
                 for (NotificationEntry child : parent.getChildren()) {
-                    child.setSection(0);
+                    child.mNotifSection = sectionWithIndex.first;
+                    child.setSection(sectionWithIndex.second);
                 }
                 parent.sortChildren(sChildComparator);
             }
@@ -754,6 +761,45 @@ public class ShadeListBuilder implements Dumpable {
         return null;
     }
 
+    private Pair<NotifSection, Integer> applySections(ListEntry entry) {
+        final Pair<NotifSection, Integer> sectionWithIndex = findSection(entry);
+        final NotifSection section = sectionWithIndex.first;
+        final Integer sectionIndex = sectionWithIndex.second;
+
+        if (section != entry.mNotifSection) {
+            if (entry.mNotifSection == null) {
+                mNotifLog.log(NotifEvent.SECTION_CHANGED, String.format(
+                        "%s: sectioned by '%s' [index=%d].",
+                        entry.getKey(),
+                        section.getName(),
+                        sectionIndex));
+            } else {
+                mNotifLog.log(NotifEvent.SECTION_CHANGED, String.format(
+                        "%s: section changed: '%s' [index=%d] -> '%s [index=%d]'.",
+                        entry.getKey(),
+                        entry.mNotifSection,
+                        entry.getSection(),
+                        section,
+                        sectionIndex));
+            }
+
+            entry.mNotifSection = section;
+            entry.setSection(sectionIndex);
+        }
+
+        return sectionWithIndex;
+    }
+
+    private Pair<NotifSection, Integer> findSection(ListEntry entry) {
+        for (int i = 0; i < mNotifSections.size(); i++) {
+            NotifSection sectioner = mNotifSections.get(i);
+            if (sectioner.isInSection(entry)) {
+                return new Pair<>(sectioner, i);
+            }
+        }
+        return new Pair<>(sDefaultSection, mNotifSections.size());
+    }
+
     private void rebuildListIfBefore(@PipelineState.StateName int state) {
         mPipelineState.requireIsBefore(state);
         if (mPipelineState.is(STATE_IDLE)) {
@@ -803,16 +849,13 @@ public class ShadeListBuilder implements Dumpable {
         void onRenderList(List<ListEntry> entries);
     }
 
-    private static class DefaultSectionsProvider extends SectionsProvider {
-        DefaultSectionsProvider() {
-            super("DefaultSectionsProvider");
-        }
-
-        @Override
-        public int getSection(ListEntry entry) {
-            return 0;
-        }
-    }
+    private static final NotifSection sDefaultSection =
+            new NotifSection("DefaultSection") {
+                @Override
+                public boolean isInSection(ListEntry entry) {
+                    return true;
+                }
+            };
 
     private static final String TAG = "NotifListBuilderImpl";
 
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/coordinator/Coordinator.java b/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/coordinator/Coordinator.java
index c1a11b2f64c8..d8b2e4089f30 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/coordinator/Coordinator.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/coordinator/Coordinator.java
@@ -17,6 +17,7 @@
 package com.android.systemui.statusbar.notification.collection.coordinator;
 
 import com.android.systemui.statusbar.notification.collection.NotifPipeline;
+import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.NotifSection;
 import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.Pluggable;
 
 /**
@@ -28,4 +29,8 @@ public interface Coordinator {
      * Coordinators should register their listeners and {@link Pluggable}s to the pipeline.
      */
     void attach(NotifPipeline pipeline);
+
+    default NotifSection getSection() {
+        return null;
+    }
 }
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/coordinator/NotifCoordinators.java b/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/coordinator/NotifCoordinators.java
index 562a618126de..8d0dd5b111ba 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/coordinator/NotifCoordinators.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/coordinator/NotifCoordinators.java
@@ -16,9 +16,11 @@
 
 package com.android.systemui.statusbar.notification.collection.coordinator;
 
+import com.android.systemui.DumpController;
 import com.android.systemui.Dumpable;
 import com.android.systemui.statusbar.FeatureFlags;
 import com.android.systemui.statusbar.notification.collection.NotifPipeline;
+import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.NotifSection;
 import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.Pluggable;
 import com.android.systemui.statusbar.notification.collection.notifcollection.NotifCollectionListener;
 import com.android.systemui.statusbar.notification.collection.notifcollection.NotifLifetimeExtender;
@@ -39,18 +41,21 @@ import javax.inject.Singleton;
 public class NotifCoordinators implements Dumpable {
     private static final String TAG = "NotifCoordinators";
     private final List<Coordinator> mCoordinators = new ArrayList<>();
-
+    private final List<NotifSection> mOrderedSections = new ArrayList<>();
     /**
      * Creates all the coordinators.
      */
     @Inject
     public NotifCoordinators(
+            DumpController dumpController,
             FeatureFlags featureFlags,
             KeyguardCoordinator keyguardCoordinator,
             RankingCoordinator rankingCoordinator,
             ForegroundCoordinator foregroundCoordinator,
             DeviceProvisionedCoordinator deviceProvisionedCoordinator,
             PreparationCoordinator preparationCoordinator) {
+        dumpController.registerDumpable(TAG, this);
+
         mCoordinators.add(keyguardCoordinator);
         mCoordinators.add(rankingCoordinator);
         mCoordinators.add(foregroundCoordinator);
@@ -59,6 +64,13 @@ public class NotifCoordinators implements Dumpable {
             mCoordinators.add(preparationCoordinator);
         }
         // TODO: add new Coordinators here! (b/145134683, b/112656837)
+
+        // TODO: add the sections in a particular ORDER (HeadsUp < People < Alerting)
+        for (Coordinator c : mCoordinators) {
+            if (c.getSection() != null) {
+                mOrderedSections.add(c.getSection());
+            }
+        }
     }
 
     /**
@@ -69,6 +81,8 @@ public class NotifCoordinators implements Dumpable {
         for (Coordinator c : mCoordinators) {
             c.attach(pipeline);
         }
+
+        pipeline.setSections(mOrderedSections);
     }
 
     @Override
@@ -78,5 +92,9 @@ public class NotifCoordinators implements Dumpable {
         for (Coordinator c : mCoordinators) {
             pw.println("\t" + c.getClass());
         }
+
+        for (NotifSection s : mOrderedSections) {
+            pw.println("\t" + s.getName());
+        }
     }
 }
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/listbuilder/pluggable/SectionsProvider.java b/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/listbuilder/pluggable/NotifSection.java
index 11ea85062781..fe5ba3c8e6fc 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/listbuilder/pluggable/SectionsProvider.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/listbuilder/pluggable/NotifSection.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2019 The Android Open Source Project
+ * Copyright (C) 2020 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,21 +17,21 @@
 package com.android.systemui.statusbar.notification.collection.listbuilder.pluggable;
 
 import com.android.systemui.statusbar.notification.collection.ListEntry;
+import com.android.systemui.statusbar.notification.collection.ShadeListBuilder;
 
 /**
- * Interface for sorting notifications into "sections", such as a heads-upping section, people
- * section, alerting section, silent section, etc.
+ * Pluggable for participating in notif sectioning. See {@link ShadeListBuilder#setSections}.
  */
-public abstract class SectionsProvider extends Pluggable<SectionsProvider> {
-
-    protected SectionsProvider(String name) {
+public abstract class NotifSection extends Pluggable<NotifSection> {
+    protected NotifSection(String name) {
         super(name);
     }
 
     /**
-     * Returns the section that this entry belongs to. A section can be any non-negative integer.
-     * When entries are sorted, they are first sorted by section and then by any remainining
-     * comparators.
+     * If returns true, this notification is considered within this section.
+     * Sectioning is performed on each top level notification each time the pipeline is run.
+     * However, this doesn't necessarily mean that your section will get called on each top-level
+     * notification. The first section to return true determines the section of the notification.
      */
-    public abstract int getSection(ListEntry entry);
+    public abstract boolean isInSection(ListEntry entry);
 }
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/logging/NotifEvent.java b/packages/SystemUI/src/com/android/systemui/statusbar/notification/logging/NotifEvent.java
index 02acc8149cc4..2374cde0c16a 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/logging/NotifEvent.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/logging/NotifEvent.java
@@ -94,7 +94,7 @@ public class NotifEvent extends RichEvent {
             LIST_BUILD_COMPLETE,
             PRE_GROUP_FILTER_INVALIDATED,
             PROMOTER_INVALIDATED,
-            SECTIONS_PROVIDER_INVALIDATED,
+            SECTION_INVALIDATED,
             COMPARATOR_INVALIDATED,
             PARENT_CHANGED,
             FILTER_CHANGED,
@@ -132,12 +132,13 @@ public class NotifEvent extends RichEvent {
                     "ListBuildComplete",
                     "FilterInvalidated",
                     "PromoterInvalidated",
-                    "SectionsProviderInvalidated",
+                    "SectionInvalidated",
                     "ComparatorInvalidated",
                     "ParentChanged",
                     "FilterChanged",
                     "PromoterChanged",
                     "FinalFilterInvalidated",
+                    "SectionerChanged",
 
                     // NEM event labels:
                     "NotifAdded",
@@ -170,13 +171,14 @@ public class NotifEvent extends RichEvent {
     public static final int LIST_BUILD_COMPLETE = 4;
     public static final int PRE_GROUP_FILTER_INVALIDATED = 5;
     public static final int PROMOTER_INVALIDATED = 6;
-    public static final int SECTIONS_PROVIDER_INVALIDATED = 7;
+    public static final int SECTION_INVALIDATED = 7;
     public static final int COMPARATOR_INVALIDATED = 8;
     public static final int PARENT_CHANGED = 9;
     public static final int FILTER_CHANGED = 10;
     public static final int PROMOTER_CHANGED = 11;
     public static final int PRE_RENDER_FILTER_INVALIDATED = 12;
-    private static final int TOTAL_LIST_BUILDER_EVENT_TYPES = 13;
+    public static final int SECTION_CHANGED = 13;
+    private static final int TOTAL_LIST_BUILDER_EVENT_TYPES = 14;
 
     /**
      * Events related to {@link NotificationEntryManager}
diff --git a/packages/SystemUI/tests/src/com/android/systemui/statusbar/notification/collection/ShadeListBuilderTest.java b/packages/SystemUI/tests/src/com/android/systemui/statusbar/notification/collection/ShadeListBuilderTest.java
index 0a235716c41f..e915be37705b 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/statusbar/notification/collection/ShadeListBuilderTest.java
+++ b/packages/SystemUI/tests/src/com/android/systemui/statusbar/notification/collection/ShadeListBuilderTest.java
@@ -19,6 +19,7 @@ package com.android.systemui.statusbar.notification.collection;
 import static com.android.systemui.statusbar.notification.collection.ListDumper.dumpTree;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyList;
@@ -47,7 +48,7 @@ import com.android.systemui.statusbar.notification.collection.listbuilder.OnBefo
 import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.NotifComparator;
 import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.NotifFilter;
 import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.NotifPromoter;
-import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.SectionsProvider;
+import com.android.systemui.statusbar.notification.collection.listbuilder.pluggable.NotifSection;
 import com.android.systemui.statusbar.notification.collection.notifcollection.CollectionReadyForBuildListener;
 import com.android.systemui.statusbar.notification.logging.NotifLog;
 import com.android.systemui.util.Assert;
@@ -450,6 +451,29 @@ public class ShadeListBuilderTest extends SysuiTestCase {
     }
 
     @Test
+    public void testPreRenderNotifsFilteredBreakupGroups() {
+        final String filterTag = "FILTER_ME";
+        // GIVEN a NotifFilter that filters out notifications with a tag
+        NotifFilter filter1 = spy(new NotifFilterWithTag(filterTag));
+        mListBuilder.addPreRenderFilter(filter1);
+
+        // WHEN the pipeline is kicked off on a list of notifs
+        addGroupChildWithTag(0, PACKAGE_2, GROUP_1, filterTag);
+        addGroupChild(1, PACKAGE_2, GROUP_1);
+        addGroupSummary(2, PACKAGE_2, GROUP_1);
+        dispatchBuild();
+
+        // THEN the final list doesn't contain any filtered-out notifs
+        // and groups that are too small are broken up
+        verifyBuiltList(
+                notif(1)
+        );
+
+        // THEN each filtered notif records the filter that did it
+        assertEquals(filter1, mEntrySet.get(0).mExcludingFilter);
+    }
+
+    @Test
     public void testNotifFiltersCanBePreempted() {
         // GIVEN two notif filters
         NotifFilter filter1 = spy(new PackageFilter(PACKAGE_2));
@@ -552,12 +576,17 @@ public class ShadeListBuilderTest extends SysuiTestCase {
     }
 
     @Test
-    public void testNotifsAreSectioned() {
-        // GIVEN a filter that removes all PACKAGE_4 notifs and a SectionsProvider that divides
+    public void testNotifSections() {
+        // GIVEN a filter that removes all PACKAGE_4 notifs and sections that divide
         // notifs based on package name
         mListBuilder.addPreGroupFilter(new PackageFilter(PACKAGE_4));
-        final SectionsProvider sectionsProvider = spy(new PackageSectioner());
-        mListBuilder.setSectionsProvider(sectionsProvider);
+        final NotifSection pkg1Section = spy(new PackageSection(PACKAGE_1));
+        final NotifSection pkg2Section = spy(new PackageSection(PACKAGE_2));
+        // NOTE: no package 3 section explicitly added, so notifs with package 3 will get set by
+        // ShadeListBuilder's sDefaultSection which will demote it to the last section
+        final NotifSection pkg4Section = spy(new PackageSection(PACKAGE_4));
+        final NotifSection pkg5Section = spy(new PackageSection(PACKAGE_5));
+        mListBuilder.setSections(Arrays.asList(pkg1Section, pkg2Section, pkg4Section, pkg5Section));
 
         // WHEN we build a list with different packages
         addNotif(0, PACKAGE_4);
@@ -584,19 +613,93 @@ public class ShadeListBuilderTest extends SysuiTestCase {
                         child(6)
                 ),
                 notif(8),
-                notif(3),
-                notif(9)
+                notif(9),
+                notif(3)
+        );
+
+        // THEN the first section (pkg1Section) is called on all top level elements (but
+        // no children and no entries that were filtered out)
+        verify(pkg1Section).isInSection(mEntrySet.get(1));
+        verify(pkg1Section).isInSection(mEntrySet.get(2));
+        verify(pkg1Section).isInSection(mEntrySet.get(3));
+        verify(pkg1Section).isInSection(mEntrySet.get(7));
+        verify(pkg1Section).isInSection(mEntrySet.get(8));
+        verify(pkg1Section).isInSection(mEntrySet.get(9));
+        verify(pkg1Section).isInSection(mBuiltList.get(3));
+
+        verify(pkg1Section, never()).isInSection(mEntrySet.get(0));
+        verify(pkg1Section, never()).isInSection(mEntrySet.get(4));
+        verify(pkg1Section, never()).isInSection(mEntrySet.get(5));
+        verify(pkg1Section, never()).isInSection(mEntrySet.get(6));
+        verify(pkg1Section, never()).isInSection(mEntrySet.get(10));
+
+        // THEN the last section (pkg5Section) is not called on any of the entries that were
+        // filtered or already in a section
+        verify(pkg5Section, never()).isInSection(mEntrySet.get(0));
+        verify(pkg5Section, never()).isInSection(mEntrySet.get(1));
+        verify(pkg5Section, never()).isInSection(mEntrySet.get(2));
+        verify(pkg5Section, never()).isInSection(mEntrySet.get(4));
+        verify(pkg5Section, never()).isInSection(mEntrySet.get(5));
+        verify(pkg5Section, never()).isInSection(mEntrySet.get(6));
+        verify(pkg5Section, never()).isInSection(mEntrySet.get(7));
+        verify(pkg5Section, never()).isInSection(mEntrySet.get(8));
+        verify(pkg5Section, never()).isInSection(mEntrySet.get(10));
+
+        verify(pkg5Section).isInSection(mEntrySet.get(3));
+        verify(pkg5Section).isInSection(mEntrySet.get(9));
+
+        // THEN the correct section is assigned for entries in pkg1Section
+        assertEquals(pkg1Section, mEntrySet.get(2).mNotifSection);
+        assertEquals(0, mEntrySet.get(2).getSection());
+        assertEquals(pkg1Section, mEntrySet.get(7).mNotifSection);
+        assertEquals(0, mEntrySet.get(7).getSection());
+
+        // THEN the correct section is assigned for entries in pkg2Section
+        assertEquals(pkg2Section, mEntrySet.get(1).mNotifSection);
+        assertEquals(1, mEntrySet.get(1).getSection());
+        assertEquals(pkg2Section, mEntrySet.get(8).mNotifSection);
+        assertEquals(1, mEntrySet.get(8).getSection());
+        assertEquals(pkg2Section, mBuiltList.get(3).mNotifSection);
+        assertEquals(1, mBuiltList.get(3).getSection());
+
+        // THEN no section was assigned to entries in pkg4Section (since they were filtered)
+        assertEquals(null, mEntrySet.get(0).mNotifSection);
+        assertEquals(-1, mEntrySet.get(0).getSection());
+        assertEquals(null, mEntrySet.get(10).mNotifSection);
+        assertEquals(-1, mEntrySet.get(10).getSection());
+
+
+        // THEN the correct section is assigned for entries in pkg5Section
+        assertEquals(pkg5Section, mEntrySet.get(9).mNotifSection);
+        assertEquals(3, mEntrySet.get(9).getSection());
+
+        // THEN the children entries are assigned the same section as its parent
+        assertEquals(mBuiltList.get(3).mNotifSection, child(5).entry.mNotifSection);
+        assertEquals(mBuiltList.get(3).getSection(), child(5).entry.getSection());
+        assertEquals(mBuiltList.get(3).mNotifSection, child(6).entry.mNotifSection);
+        assertEquals(mBuiltList.get(3).getSection(), child(6).entry.getSection());
+    }
+
+    @Test
+    public void testNotifUsesDefaultSection() {
+        // GIVEN a Section for Package2
+        final NotifSection pkg2Section = spy(new PackageSection(PACKAGE_2));
+        mListBuilder.setSections(Arrays.asList(pkg2Section));
+
+        // WHEN we build a list with pkg1 and pkg2 packages
+        addNotif(0, PACKAGE_1);
+        addNotif(1, PACKAGE_2);
+        dispatchBuild();
+
+        // THEN the list is sorted according to section
+        verifyBuiltList(
+                notif(1),
+                notif(0)
         );
 
-        // THEN the sections provider is called on all top level elements (but no children and no
-        // entries that were filtered out)
-        verify(sectionsProvider).getSection(mEntrySet.get(1));
-        verify(sectionsProvider).getSection(mEntrySet.get(2));
-        verify(sectionsProvider).getSection(mEntrySet.get(3));
-        verify(sectionsProvider).getSection(mEntrySet.get(7));
-        verify(sectionsProvider).getSection(mEntrySet.get(8));
-        verify(sectionsProvider).getSection(mEntrySet.get(9));
-        verify(sectionsProvider).getSection(mBuiltList.get(3));
+        // THEN the entry that didn't have an explicit section gets assigned the DefaultSection
+        assertEquals(1, notif(0).entry.getSection());
+        assertNotNull(notif(0).entry.mNotifSection);
     }
 
     @Test
@@ -631,7 +734,7 @@ public class ShadeListBuilderTest extends SysuiTestCase {
         // GIVEN a bunch of registered listeners and pluggables
         NotifFilter preGroupFilter = spy(new PackageFilter(PACKAGE_1));
         NotifPromoter promoter = spy(new IdPromoter(3));
-        PackageSectioner sectioner = spy(new PackageSectioner());
+        NotifSection section = spy(new PackageSection(PACKAGE_1));
         NotifComparator comparator = spy(new HypeComparator(PACKAGE_4));
         NotifFilter preRenderFilter = spy(new PackageFilter(PACKAGE_5));
         mListBuilder.addPreGroupFilter(preGroupFilter);
@@ -639,7 +742,7 @@ public class ShadeListBuilderTest extends SysuiTestCase {
         mListBuilder.addPromoter(promoter);
         mListBuilder.addOnBeforeSortListener(mOnBeforeSortListener);
         mListBuilder.setComparators(Collections.singletonList(comparator));
-        mListBuilder.setSectionsProvider(sectioner);
+        mListBuilder.setSections(Arrays.asList(section));
         mListBuilder.addOnBeforeRenderListListener(mOnBeforeRenderListListener);
         mListBuilder.addPreRenderFilter(preRenderFilter);
 
@@ -659,7 +762,7 @@ public class ShadeListBuilderTest extends SysuiTestCase {
                 mOnBeforeTransformGroupsListener,
                 promoter,
                 mOnBeforeSortListener,
-                sectioner,
+                section,
                 comparator,
                 preRenderFilter,
                 mOnBeforeRenderListListener,
@@ -672,7 +775,7 @@ public class ShadeListBuilderTest extends SysuiTestCase {
         inOrder.verify(promoter, atLeastOnce())
                 .shouldPromoteToTopLevel(any(NotificationEntry.class));
         inOrder.verify(mOnBeforeSortListener).onBeforeSort(anyList());
-        inOrder.verify(sectioner, atLeastOnce()).getSection(any(ListEntry.class));
+        inOrder.verify(section, atLeastOnce()).isInSection(any(ListEntry.class));
         inOrder.verify(comparator, atLeastOnce())
                 .compare(any(ListEntry.class), any(ListEntry.class));
         inOrder.verify(preRenderFilter, atLeastOnce())
@@ -686,12 +789,12 @@ public class ShadeListBuilderTest extends SysuiTestCase {
         // GIVEN a variety of pluggables
         NotifFilter packageFilter = new PackageFilter(PACKAGE_1);
         NotifPromoter idPromoter = new IdPromoter(4);
-        SectionsProvider sectionsProvider = new PackageSectioner();
+        NotifSection section = new PackageSection(PACKAGE_1);
         NotifComparator hypeComparator = new HypeComparator(PACKAGE_2);
 
         mListBuilder.addPreGroupFilter(packageFilter);
         mListBuilder.addPromoter(idPromoter);
-        mListBuilder.setSectionsProvider(sectionsProvider);
+        mListBuilder.setSections(Arrays.asList(section));
         mListBuilder.setComparators(Collections.singletonList(hypeComparator));
 
         // GIVEN a set of random notifs
@@ -711,7 +814,7 @@ public class ShadeListBuilderTest extends SysuiTestCase {
         verify(mOnRenderListListener).onRenderList(anyList());
 
         clearInvocations(mOnRenderListListener);
-        sectionsProvider.invalidateList();
+        section.invalidateList();
         verify(mOnRenderListListener).onRenderList(anyList());
 
         clearInvocations(mOnRenderListListener);
@@ -984,9 +1087,10 @@ public class ShadeListBuilderTest extends SysuiTestCase {
         return builder;
     }
 
-    /** Same behavior as {@link #addNotif(int, String)}. */
-    private NotificationEntryBuilder addGroupChild(int index, String packageId, String groupId) {
+    private NotificationEntryBuilder addGroupChildWithTag(int index, String packageId,
+            String groupId, String tag) {
         final NotificationEntryBuilder builder = new NotificationEntryBuilder()
+                .setTag(tag)
                 .setPkg(packageId)
                 .setId(nextId(packageId))
                 .setRank(nextRank());
@@ -1001,6 +1105,11 @@ public class ShadeListBuilderTest extends SysuiTestCase {
         return builder;
     }
 
+    /** Same behavior as {@link #addNotif(int, String)}. */
+    private NotificationEntryBuilder addGroupChild(int index, String packageId, String groupId) {
+        return addGroupChildWithTag(index, packageId, groupId, null);
+    }
+
     private int nextId(String packageName) {
         Integer nextId = mNextIdMap.get(packageName);
         if (nextId == null) {
@@ -1169,6 +1278,21 @@ public class ShadeListBuilderTest extends SysuiTestCase {
         }
     }
 
+    /** Filters out notifications with a particular tag */
+    private static class NotifFilterWithTag extends NotifFilter {
+        private final String mTag;
+
+        NotifFilterWithTag(String tag) {
+            super("NotifFilterWithTag_" + tag);
+            mTag = tag;
+        }
+
+        @Override
+        public boolean shouldFilterOut(NotificationEntry entry, long now) {
+            return Objects.equals(entry.getSbn().getTag(), mTag);
+        }
+    }
+
     /** Promotes notifs with particular IDs */
     private static class IdPromoter extends NotifPromoter {
         private final List<Integer> mIds;
@@ -1205,25 +1329,18 @@ public class ShadeListBuilderTest extends SysuiTestCase {
         }
     }
 
-    /** Sorts notifs into sections based on their package name */
-    private static class PackageSectioner extends SectionsProvider {
+    /** Represents a section for the passed pkg */
+    private static class PackageSection extends NotifSection {
+        private final String mPackage;
 
-        PackageSectioner() {
-            super("PackageSectioner");
+        PackageSection(String pkg) {
+            super("PackageSection_" + pkg);
+            mPackage = pkg;
         }
 
         @Override
-        public int getSection(ListEntry entry) {
-            switch (entry.getRepresentativeEntry().getSbn().getPackageName()) {
-                case PACKAGE_1:
-                    return 1;
-                case PACKAGE_2:
-                    return 2;
-                case PACKAGE_3:
-                    return 3;
-                default:
-                    return 4;
-            }
+        public boolean isInSection(ListEntry entry) {
+            return entry.getRepresentativeEntry().getSbn().getPackageName().equals(mPackage);
         }
     }