test(calcite): cover filter push-down + aggregate-rule branches (Sonar new-coverage gate)

SonarCloud quality gate was ERROR: new_coverage 74% < 80%, concentrated in the
new calcite adapter. Add tests for the uncovered paths — no production changes:

- FilterPushDownTest: JDBC WHERE over every supported comparison, Utf8/float
  literal coercion, multi-conjunct AND, non-pushable bool/bare-ref predicates
  (exercises toRowFilter/binary/collectColumns).
- AggregateRuleBranchTest: Hep planner asserts rewrite-to-Values vs abandon for
  COUNT(*), COUNT(col), SUM (no stat), MIN(varchar), MIN(expr), GROUP BY.
- VortexAdapterCoverageTest: missing-file UncheckedIOException paths, reset()/
  close-with-open-chunk, i32/f32 sums, non-numeric-column throw.

calcite new-code coverage 74% -> 88.5% lines / 83.2% line+branch units.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: dfa1

calcite/src/test/java/io/github/dfa1/vortex/calcite/AggregateRuleBranchTest.java

@@ -0,0 +1,108 @@
+package io.github.dfa1.vortex.calcite;
+
+import org.apache.calcite.avatica.util.Casing;
+import org.apache.calcite.plan.RelOptUtil;
+import org.apache.calcite.plan.hep.HepPlanner;
+import org.apache.calcite.plan.hep.HepProgram;
+import org.apache.calcite.plan.hep.HepProgramBuilder;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.schema.SchemaPlus;
+import org.apache.calcite.sql.SqlNode;
+import org.apache.calcite.sql.parser.SqlParser;
+import org.apache.calcite.tools.FrameworkConfig;
+import org.apache.calcite.tools.Frameworks;
+import org.apache.calcite.tools.Planner;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+import java.nio.file.Path;
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/// Branch coverage for [VortexAggregatePushDownRule]: each query either rewrites to a single-row
+/// `LogicalValues` (answerable from zone-map stats) or is left with its `Aggregate`/`TableScan`
+/// intact (the rule must abandon — wrong stats would give a wrong answer).
+class AggregateRuleBranchTest {
+
+    private static final int ROWS = 30_000;
+    private static final int CHUNK = 10_000;
+
+    @TempDir
+    static Path tmp;
+    private static SchemaPlus schema;
+
+    @BeforeAll
+    static void writeFile() throws Exception {
+        Path file = tmp.resolve("ohlc.vortex");
+        OhlcGenerator.write(file, ROWS, CHUNK);
+        SchemaPlus root = Frameworks.createRootSchema(true);
+        schema = root.add("vtx", new VortexSchema(Map.of("ohlc", file)));
+    }
+
+    @Test
+    void countStar_noProjectPath_rewritesToValues() {
+        // Given a bare COUNT(*) — Aggregate(TableScan), the NO_PROJECT operand with project == null
+        // When / Then — answered from the footer row count
+        assertThat(optimize("select count(*) from ohlc")).contains("LogicalValues").doesNotContain("Aggregate");
+    }
+
+    @Test
+    void countColumn_withProjectPath_rewritesToValues() {
+        // Given COUNT(volume) — Aggregate(Project(TableScan)); COUNT(col) = rows − nulls from stats
+        // When / Then
+        assertThat(optimize("select count(volume) from ohlc")).contains("LogicalValues").doesNotContain("Aggregate");
+    }
+
+    @Test
+    void sum_hasNoZoneStat_abandonsRewrite() {
+        // Given SUM(volume) — no SUM zone statistic exists, so evaluate() yields null and the whole
+        // rewrite is abandoned
+        // When / Then — the Aggregate survives for the normal scan path
+        assertThat(optimize("select sum(volume) from ohlc")).contains("Aggregate");
+    }
+
+    @Test
+    void minOnNonNumericColumn_abandonsRewrite() {
+        // Given MIN(symbol) over a VARCHAR column — the stat value is non-numeric, numericLiteral
+        // returns null, the rewrite is abandoned
+        // When / Then
+        assertThat(optimize("select min(symbol) from ohlc")).contains("Aggregate");
+    }
+
+    @Test
+    void minOverComputedExpression_abandonsRewrite() {
+        // Given MIN(low + 1) — the projected input is an expression, not a bare column ref, so
+        // resolveColumn returns null and the rewrite is abandoned
+        // When / Then
+        assertThat(optimize("select min(low + 1) from ohlc")).contains("Aggregate");
+    }
+
+    @Test
+    void groupedAggregate_isLeftUntouched() {
+        // Given a GROUP BY — group count != 0, the rule returns immediately
+        // When / Then — Aggregate stays
+        assertThat(optimize("select symbol, max(high) from ohlc group by symbol")).contains("Aggregate");
+    }
+
+    private static String optimize(String sql) {
+        FrameworkConfig config = Frameworks.newConfigBuilder()
+                .defaultSchema(schema)
+                .parserConfig(SqlParser.config().withUnquotedCasing(Casing.UNCHANGED))
+                .build();
+        Planner planner = Frameworks.getPlanner(config);
+        try {
+            SqlNode parsed = planner.parse(sql);
+            RelNode logical = planner.rel(planner.validate(parsed)).rel;
+            HepProgram program = new HepProgramBuilder()
+                    .addRuleCollection(VortexAggregatePushDownRule.RULES)
+                    .build();
+            HepPlanner hep = new HepPlanner(program);
+            hep.setRoot(logical);
+            return RelOptUtil.toString(hep.findBestExp());
+        } catch (Exception e) {
+            throw new IllegalStateException("planning failed for: " + sql, e);
+        }
+    }
+}

calcite/src/test/java/io/github/dfa1/vortex/calcite/FilterPushDownTest.java

@@ -0,0 +1,103 @@
+package io.github.dfa1.vortex.calcite;
+
+import io.github.dfa1.vortex.core.model.DType;
+import io.github.dfa1.vortex.writer.VortexWriter;
+import io.github.dfa1.vortex.writer.WriteOptions;
+
+import org.apache.calcite.jdbc.CalciteConnection;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.io.TempDir;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+import java.nio.channels.FileChannel;
+import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.ResultSet;
+import java.sql.Statement;
+import java.util.Map;
+import java.util.Properties;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/// Drives [VortexTable]'s filter push-down (`scan(root, filters, projects)`) through a real Calcite
+/// JDBC planner: every supported `WHERE` comparison must be translated into a zone-map [RowFilter]
+/// (so the scan can prune chunks) while Calcite still returns the exact rows. Predicates the
+/// translator does not understand must be left untouched, not break the query.
+class FilterPushDownTest {
+
+    // Two chunks of three rows so the pushed RowFilter has chunks to (potentially) prune.
+    private static final DType.Struct SCHEMA = DType.structBuilder()
+            .field("i64", DType.I64)
+            .field("i32", DType.I32)
+            .field("f64", DType.F64)
+            .field("s", DType.UTF8)
+            .field("b", DType.BOOL)
+            .build();
+
+    @TempDir
+    static Path tmp;
+    private static Path file;
+
+    @BeforeAll
+    static void write() throws Exception {
+        file = tmp.resolve("filter.vortex");
+        try (var ch = FileChannel.open(file, StandardOpenOption.CREATE, StandardOpenOption.WRITE);
+             var w = VortexWriter.create(ch, SCHEMA, WriteOptions.defaults())) {
+            w.writeChunk(Map.of(
+                    "i64", new long[]{1000L, 2000L, 3000L},
+                    "i32", new int[]{100, 200, 300},
+                    "f64", new double[]{1.0, 2.0, 3.0},
+                    "s", new String[]{"a", "b", "c"},
+                    "b", new boolean[]{true, false, true}));
+            w.writeChunk(Map.of(
+                    "i64", new long[]{4000L, 5000L, 6000L},
+                    "i32", new int[]{400, 500, 600},
+                    "f64", new double[]{4.0, 5.0, 6.0},
+                    "s", new String[]{"d", "e", "f"},
+                    "b", new boolean[]{false, true, false}));
+        }
+    }
+
+    @ParameterizedTest(name = "[{index}] WHERE {0} -> {1} rows")
+    @CsvSource({
+            // every comparison kind the RowFilter translator supports, over a Long column
+            "i64 = 1000,            1",   // EQUALS        -> RowFilter.Eq
+            "i64 <> 1000,           5",   // NOT_EQUALS    -> RowFilter.Neq
+            "i64 < 3000,            2",   // LESS_THAN     -> RowFilter.Lt
+            "i64 <= 3000,           3",   // LESS_THAN_EQ  -> RowFilter.Lte
+            "i64 > 4000,            2",   // GREATER_THAN  -> RowFilter.Gt
+            "i64 >= 4000,           3",   // GREATER_EQ    -> RowFilter.Gte
+            "s = 'a',               1",   // Utf8 literal coercion
+            "f64 > 3.0,             3",   // floating literal coercion
+            // multiple conjuncts arrive as separate filters -> RowFilter.and over the list
+            "i64 > 1000 AND i32 < 600, 4",
+            // bare boolean ref is not a RexCall -> not pushed, query still exact
+            "b,                     3",
+            // comparison on a BOOLEAN column has no zone-map coercion -> not pushed, still exact
+            "b = true,              3"
+    })
+    void whereClauseIsPushedAndRowsStayExact(String where, int expected) throws Exception {
+        // Given a Calcite JDBC connection over the Vortex file
+        Properties info = new Properties();
+        info.setProperty("lex", "JAVA");
+        try (Connection conn = DriverManager.getConnection("jdbc:calcite:", info)) {
+            conn.unwrap(CalciteConnection.class).getRootSchema()
+                    .add("vtx", new VortexSchema(Map.of("data", file)));
+
+            // When the filtered query runs (Calcite pushes the predicate into VortexTable.scan)
+            int rows = 0;
+            try (Statement st = conn.createStatement();
+                 ResultSet rs = st.executeQuery("select i64 from vtx.data where " + where)) {
+                while (rs.next()) {
+                    rows++;
+                }
+            }
+
+            // Then the row count is exact regardless of whether the predicate was pushed
+            assertThat(rows).isEqualTo(expected);
+        }
+    }
+}

calcite/src/test/java/io/github/dfa1/vortex/calcite/VortexAdapterCoverageTest.java

@@ -131,6 +131,52 @@ void table_totalRowsAndStats() {
         assertThat(table.statsOf("i64")).isNotNull();
     }
 
+    @Test
+    void enumerator_resetUnsupportedAndCloseReleasesOpenChunk() {
+        // Given a scan positioned inside the first chunk
+        Enumerator<Object[]> en = new VortexTable(file).scan(null, List.of(), null).enumerator();
+        assertThat(en.moveNext()).isTrue();
+
+        // When / Then — reset is unsupported, and close must release the still-open chunk cleanly
+        assertThatThrownBy(en::reset).isInstanceOf(UnsupportedOperationException.class);
+        en.close();
+    }
+
+    @Nested
+    class MissingFile {
+
+        // A path that does not exist makes VortexReader.open throw IOException, which every entry
+        // point wraps as UncheckedIOException — these are the file-open failure branches.
+        private final VortexTable table = new VortexTable(tmp.resolve("does-not-exist.vortex"));
+
+        @Test
+        void getRowType_wrapsOpenFailure() {
+            // When / Then
+            assertThatThrownBy(() -> table.getRowType(new JavaTypeFactoryImpl()))
+                    .isInstanceOf(java.io.UncheckedIOException.class);
+        }
+
+        @Test
+        void statsOf_wrapsOpenFailure() {
+            // When / Then
+            assertThatThrownBy(() -> table.statsOf("i64"))
+                    .isInstanceOf(java.io.UncheckedIOException.class);
+        }
+
+        @Test
+        void totalRows_wrapsOpenFailure() {
+            // When / Then
+            assertThatThrownBy(table::totalRows).isInstanceOf(java.io.UncheckedIOException.class);
+        }
+
+        @Test
+        void scan_wrapsOpenFailure() {
+            // When / Then — the enumerator constructor opens the reader and wraps the failure
+            assertThatThrownBy(() -> table.scan(null, List.of(), null).enumerator())
+                    .isInstanceOf(java.io.UncheckedIOException.class);
+        }
+    }
+
     @Nested
     class Schema {
 
@@ -187,5 +233,38 @@ void floatColumn_sumIsDouble() throws Exception {
                 assertThat(s.avg()).isEqualTo(2.25);
             }
         }
+
+        @Test
+        void narrowIntColumn_sumsViaIntArrayIntoLong() throws Exception {
+            // Given / When — i32 decodes to IntArray, summed into a long (exact)
+            try (VortexReader reader = VortexReader.open(file, registry())) {
+                VortexAggregates.Summary s = VortexAggregates.of(reader, "i32");
+
+                // Then
+                assertThat(s.sum()).isInstanceOf(Long.class).isEqualTo(600L); // 100+200+300
+            }
+        }
+
+        @Test
+        void floatColumn_sumsViaFloatArrayIntoDouble() throws Exception {
+            // Given / When — f32 decodes to FloatArray, accumulated into a double
+            try (VortexReader reader = VortexReader.open(file, registry())) {
+                VortexAggregates.Summary s = VortexAggregates.of(reader, "f32");
+
+                // Then
+                assertThat(s.sum()).isInstanceOf(Double.class);
+                assertThat(s.sum().doubleValue()).isEqualTo(7.5); // 1.5+2.5+3.5
+            }
+        }
+
+        @Test
+        void nonNumericColumn_throws() throws Exception {
+            // Given / When / Then — a UTF8 column has no numeric array branch
+            try (VortexReader reader = VortexReader.open(file, registry())) {
+                assertThatThrownBy(() -> VortexAggregates.of(reader, "s"))
+                        .isInstanceOf(IllegalArgumentException.class)
+                        .hasMessageContaining("not a numeric column");
+            }
+        }
     }
 }