diff --git a/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/JsonDocument.java b/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/JsonDocument.java
index cb85902..0745d92 100644
--- a/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/JsonDocument.java
+++ b/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/JsonDocument.java
@@ -87,4 +87,21 @@ public class JsonDocument {
     public static void load(ThrowawayDatabase db) {
         load(db, TEST_TABLE);
     }
+
+    /** Document ID <code>one</code> as a JSON string */
+    public static String one = "{\"id\":\"one\",\"value\":\"FIRST!\",\"numValue\":0,\"sub\":null}";
+
+    /** Document ID <code>two</code> as a JSON string */
+    public static String two = "{\"id\":\"two\",\"value\":\"another\",\"numValue\":10,"
+            + "\"sub\":{\"foo\":\"green\",\"bar\":\"blue\"}}";
+
+    /** Document ID <code>three</code> as a JSON string */
+    public static String three = "{\"id\":\"three\",\"value\":\"\",\"numValue\":4,\"sub\":null}";
+
+    /** Document ID <code>four</code> as a JSON string */
+    public static String four = "{\"id\":\"four\",\"value\":\"purple\",\"numValue\":17,"
+            + "\"sub\":{\"foo\":\"green\",\"bar\":\"red\"}}";
+
+    /** Document ID <code>five</code> as a JSON string */
+    public static String five = "{\"id\":\"five\",\"value\":\"purple\",\"numValue\":18,\"sub\":null}";
 }
diff --git a/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/JsonFunctions.java b/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/JsonFunctions.java
index 0d440d2..646e386 100644
--- a/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/JsonFunctions.java
+++ b/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/JsonFunctions.java
@@ -1,10 +1,25 @@
 package solutions.bitbadger.documents.core.tests.java.integration;
 
-import solutions.bitbadger.documents.Configuration;
-import solutions.bitbadger.documents.Dialect;
-import solutions.bitbadger.documents.DocumentException;
+import solutions.bitbadger.documents.*;
+import solutions.bitbadger.documents.core.tests.integration.ThrowawayDatabase;
 
-public class JsonFunctions {
+import java.util.List;
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static solutions.bitbadger.documents.core.tests.TypesKt.TEST_TABLE;
+import static solutions.bitbadger.documents.java.extensions.ConnExt.*;
+
+/**
+ * Tests for the JSON-returning functions
+ * <p>
+ * NOTE: PostgreSQL JSONB columns do not preserve the original JSON with which a document was stored. These tests are
+ * the most complex within the library, as they have split testing based on the backing data store. The PostgreSQL tests
+ * check IDs (and, in the case of ordered queries, which ones occur before which others) vs. the entire JSON string.
+ * Meanwhile, SQLite stores JSON as text, and will return exactly the JSON it was given when it was originally written.
+ * These tests can ensure the expected round-trip of the entire JSON string.
+ */
+final public class JsonFunctions {
 
     /**
      * PostgreSQL, when returning JSONB as a string, has spaces after commas and colons delineating fields and values.
@@ -14,9 +29,396 @@ public class JsonFunctions {
      * @return The actual expected JSON based on the database being tested
      */
     public static String maybeJsonB(String json) throws DocumentException {
-        if (Configuration.dialect() == Dialect.SQLITE) {
-            return json;
+        return switch (Configuration.dialect()) {
+            case SQLITE -> json;
+            case POSTGRESQL -> json.replace("\":", "\": ").replace(",\"", ", \"");
+        };
+    }
+
+    /**
+     * Create a snippet of JSON to find a document ID
+     *
+     * @param id The ID of the document
+     * @return A connection-aware ID to check for presence and positioning
+     */
+    private static String docId(String id) throws DocumentException {
+        return maybeJsonB(String.format("{\"id\":\"%s\"", id));
+    }
+
+    public static void allDefault(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonAll(db.getConn(), TEST_TABLE);
+        assertTrue(json.startsWith("["), "JSON should start with '[' ($json)");
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertTrue(json.contains(JsonDocument.one),
+                        String.format("Document 'one' not found in JSON (%s)", json));
+                assertTrue(json.contains(JsonDocument.two),
+                        String.format("Document 'two' not found in JSON (%s)", json));
+                assertTrue(json.contains(JsonDocument.three),
+                        String.format("Document 'three' not found in JSON (%s)", json));
+                assertTrue(json.contains(JsonDocument.four),
+                        String.format("Document 'four' not found in JSON (%s)", json));
+                assertTrue(json.contains(JsonDocument.five),
+                        String.format("Document 'five' not found in JSON (%s)", json));
+                break;
+            case POSTGRESQL:
+                assertTrue(json.contains(docId("one")), String.format("Document 'one' not found in JSON (%s)", json));
+                assertTrue(json.contains(docId("two")), String.format("Document 'two' not found in JSON (%s)", json));
+                assertTrue(json.contains(docId("three")),
+                        String.format("Document 'three' not found in JSON (%s)", json));
+                assertTrue(json.contains(docId("four")), String.format("Document 'four' not found in JSON (%s)", json));
+                assertTrue(json.contains(docId("five")), String.format("Document 'five' not found in JSON (%s)", json));
+                break;
         }
-        return json.replace("\":\"", "\": \"").replace("\",\"", "\", \"").replace("\":[", "\": [");
+        assertTrue(json.endsWith("]"), "JSON should end with ']' ($json)");
+    }
+
+    public static void allEmpty(ThrowawayDatabase db) throws DocumentException {
+        assertEquals("[]", jsonAll(db.getConn(), TEST_TABLE), "There should have been no documents returned");
+    }
+
+    public static void byIdString(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonById(db.getConn(), TEST_TABLE, "two");
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertEquals(JsonDocument.two, json, "An incorrect document was returned");
+                break;
+            case POSTGRESQL:
+                assertTrue(json.contains(docId("two")), String.format("An incorrect document was returned (%s)", json));
+                break;
+        }
+    }
+
+    public static void byIdNumber(ThrowawayDatabase db) throws DocumentException {
+        Configuration.idField = "key";
+        try {
+            insert(db.getConn(), TEST_TABLE, new NumIdDocument(18, "howdy"));
+            assertEquals(maybeJsonB("{\"key\":18,\"text\":\"howdy\"}"), jsonById(db.getConn(), TEST_TABLE, 18),
+                    "The document should have been found by numeric ID");
+        } finally {
+            Configuration.idField = "id";
+        }
+    }
+
+    public static void byIdNotFound(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        assertEquals("{}", jsonById(db.getConn(), TEST_TABLE, "x"), "There should have been no document returned");
+    }
+
+    public static void byFieldsMatch(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonByFields(db.getConn(), TEST_TABLE,
+                List.of(Field.any("value", List.of("blue", "purple")), Field.exists("sub")), FieldMatch.ALL);
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertEquals(String.format("[%s]", JsonDocument.four), json, "The incorrect document was returned");
+                break;
+            case POSTGRESQL:
+                assertTrue(json.startsWith("["), String.format("JSON should start with '[' (%s)", json));
+                assertTrue(json.contains(docId("four")),
+                        String.format("The incorrect document was returned (%s)", json));
+                assertTrue(json.endsWith("]"), String.format("JSON should end with ']' (%s)", json));
+                break;
+        }
+    }
+
+    public static void byFieldsMatchOrdered(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonByFields(db.getConn(), TEST_TABLE, List.of(Field.equal("value", "purple")), null,
+                List.of(Field.named("id")));
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertEquals(String.format("[%s,%s]", JsonDocument.five, JsonDocument.four), json,
+                        "The documents were not ordered correctly");
+                break;
+            case POSTGRESQL:
+                final int fiveIdx = json.indexOf(docId("five"));
+                final int fourIdx = json.indexOf(docId("four"));
+                assertTrue(json.startsWith("["), String.format("JSON should start with '[' (%s)", json));
+                assertTrue(fiveIdx >= 0, String.format("Document 'five' not found (%s)", json));
+                assertTrue(fourIdx >= 0, String.format("Document 'four' not found (%s)", json));
+                assertTrue(fiveIdx < fourIdx,
+                        String.format("Document 'five' should have been before 'four' (%s)", json));
+                assertTrue(json.endsWith("]"), String.format("JSON should end with ']' (%s)", json));
+                break;
+        }
+    }
+
+    public static void byFieldsMatchNumIn(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonByFields(db.getConn(), TEST_TABLE, List.of(Field.any("numValue", List.of(2, 4, 6, 8))));
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertEquals(String.format("[%s]", JsonDocument.three), json, "The incorrect document was returned");
+                break;
+            case POSTGRESQL:
+                assertTrue(json.startsWith("["), String.format("JSON should start with '[' (%s)", json));
+                assertTrue(json.contains(docId("three")),
+                        String.format("The incorrect document was returned (%s)", json));
+                assertTrue(json.endsWith("]"), String.format("JSON should end with ']' (%s)", json));
+                break;
+        }
+    }
+
+    public static void byFieldsNoMatch(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        assertEquals("[]", jsonByFields(db.getConn(), TEST_TABLE, List.of(Field.greater("numValue", 100))),
+                "There should have been no documents returned");
+    }
+
+    public static void byFieldsMatchInArray(ThrowawayDatabase db) throws DocumentException {
+        for (ArrayDocument doc : ArrayDocument.testDocuments) { insert(db.getConn(), TEST_TABLE, doc); }
+        final String json = jsonByFields(db.getConn(), TEST_TABLE, List.of(Field.inArray("values", TEST_TABLE,
+                List.of("c"))));
+        assertTrue(json.startsWith("["), String.format("JSON should start with '[' (%s)", json));
+        assertTrue(json.contains(docId("first")), String.format("The 'first' document was not found (%s)", json));
+        assertTrue(json.contains(docId("second")), String.format("The 'second' document was not found (%s)", json));
+        assertTrue(json.endsWith("]"), String.format("JSON should end with ']' (%s)", json));
+    }
+
+    public static void byFieldsNoMatchInArray(ThrowawayDatabase db) throws DocumentException {
+        for (ArrayDocument doc : ArrayDocument.testDocuments) { insert(db.getConn(), TEST_TABLE, doc); }
+        assertEquals("[]",
+                jsonByFields(db.getConn(), TEST_TABLE, List.of(Field.inArray("values", TEST_TABLE, List.of("j")))),
+                "There should have been no documents returned");
+    }
+
+    public static void byContainsMatch(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonByContains(db.getConn(), TEST_TABLE, Map.of("value", "purple"));
+        assertTrue(json.startsWith("["), String.format("JSON should start with '[' (%s)", json));
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertTrue(json.contains(JsonDocument.four), String.format("Document 'four' not found (%s)", json));
+                assertTrue(json.contains(JsonDocument.five), String.format("Document 'five' not found (%s)", json));
+                break;
+            case POSTGRESQL:
+                assertTrue(json.contains(docId("four")), String.format("Document 'four' not found (%s)", json));
+                assertTrue(json.contains(docId("five")), String.format("Document 'five' not found (%s)", json));
+                break;
+        }
+        assertTrue(json.endsWith("]"), String.format("JSON should end with ']' (%s)", json));
+    }
+
+    public static void byContainsMatchOrdered(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonByContains(db.getConn(), TEST_TABLE, Map.of("sub", Map.of("foo", "green")),
+                List.of(Field.named("value")));
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertEquals(String.format("[%s,%s]", JsonDocument.two, JsonDocument.four), json,
+                        "The documents were not ordered correctly");
+                break;
+            case POSTGRESQL:
+                final int twoIdx = json.indexOf(docId("two"));
+                final int fourIdx = json.indexOf(docId("four"));
+                assertTrue(json.startsWith("["), String.format("JSON should start with '[' (%s)", json));
+                assertTrue(twoIdx >= 0, String.format("Document 'two' not found (%s)", json));
+                assertTrue(fourIdx >= 0, String.format("Document 'four' not found (%s)", json));
+                assertTrue(twoIdx < fourIdx, String.format("Document 'two' should have been before 'four' (%s)", json));
+                assertTrue(json.endsWith("]"), String.format("JSON should end with ']' (%s)", json));
+                break;
+        }
+    }
+
+    public static void byContainsNoMatch(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        assertEquals("[]", jsonByContains(db.getConn(), TEST_TABLE, Map.of("value", "indigo")),
+                "There should have been no documents returned");
+    }
+
+    public static void byJsonPathMatch(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonByJsonPath(db.getConn(), TEST_TABLE, "$.numValue ? (@ > 10)");
+        assertTrue(json.startsWith("["), String.format("JSON should start with '[' (%s)", json));
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertTrue(json.contains(JsonDocument.four), String.format("Document 'four' not found (%s)", json));
+                assertTrue(json.contains(JsonDocument.five), String.format("Document 'five' not found (%s)", json));
+                break;
+            case POSTGRESQL:
+                assertTrue(json.contains(docId("four")), String.format("Document 'four' not found (%s)", json));
+                assertTrue(json.contains(docId("five")), String.format("Document 'five' not found (%s)", json));
+                break;
+        }
+        assertTrue(json.endsWith("]"), String.format("JSON should end with ']' (%s)", json));
+    }
+
+    public static void byJsonPathMatchOrdered(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonByJsonPath(db.getConn(), TEST_TABLE, "$.numValue ? (@ > 10)",
+                List.of(Field.named("id")));
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertEquals(String.format("[%s,%s]", JsonDocument.five, JsonDocument.four), json,
+                        "The documents were not ordered correctly");
+                break;
+            case POSTGRESQL:
+                final int fiveIdx = json.indexOf(docId("five"));
+                final int fourIdx = json.indexOf(docId("four"));
+                assertTrue(json.startsWith("["), String.format("JSON should start with '[' (%s)", json));
+                assertTrue(fiveIdx >= 0, String.format("Document 'five' not found (%s)", json));
+                assertTrue(fourIdx >= 0, String.format("Document 'four' not found (%s)", json));
+                assertTrue(fiveIdx < fourIdx,
+                        String.format("Document 'five' should have been before 'four' (%s)", json));
+                assertTrue(json.endsWith("]"), String.format("JSON should end with ']' (%s)", json));
+                break;
+        }
+    }
+
+    public static void byJsonPathNoMatch(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        assertEquals("[]", jsonByJsonPath(db.getConn(), TEST_TABLE, "$.numValue ? (@ > 100)"),
+                "There should have been no documents returned");
+    }
+
+    public static void firstByFieldsMatchOne(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonFirstByFields(db.getConn(), TEST_TABLE, List.of(Field.equal("value", "another")));
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertEquals(JsonDocument.two, json, "The incorrect document was returned");
+                break;
+            case POSTGRESQL:
+                assertTrue(json.contains(docId("two")),
+                        String.format("The incorrect document was returned (%s)", json));
+                break;
+        }
+    }
+
+    public static void firstByFieldsMatchMany(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonFirstByFields(db.getConn(), TEST_TABLE, List.of(Field.equal("sub.foo", "green")));
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertTrue(json.contains(JsonDocument.two) || json.contains(JsonDocument.four),
+                        String.format("Expected document 'two' or 'four' (%s)", json));
+                break;
+            case POSTGRESQL:
+                assertTrue(json.contains(docId("two")) || json.contains(docId("four")),
+                        String.format("Expected document 'two' or 'four' (%s)", json));
+                break;
+        }
+    }
+
+    public static void firstByFieldsMatchOrdered(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonFirstByFields(db.getConn(), TEST_TABLE, List.of(Field.equal("sub.foo", "green")), null,
+                List.of(Field.named("n:numValue DESC")));
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertEquals(JsonDocument.four, json, "An incorrect document was returned");
+                break;
+            case POSTGRESQL:
+                assertTrue(json.contains(docId("four")),
+                        String.format("An incorrect document was returned (%s)", json));
+                break;
+        }
+    }
+
+    public static void firstByFieldsNoMatch(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        assertEquals("{}", jsonFirstByFields(db.getConn(), TEST_TABLE, List.of(Field.equal("value", "absent"))),
+                "There should have been no document returned");
+    }
+
+    public static void firstByContainsMatchOne(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonFirstByContains(db.getConn(), TEST_TABLE, Map.of("value", "FIRST!"));
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertEquals(JsonDocument.one, json, "An incorrect document was returned");
+                break;
+            case POSTGRESQL:
+                assertTrue(json.contains(docId("one")), String.format("An incorrect document was returned (%s)", json));
+                break;
+        }
+    }
+
+    public static void firstByContainsMatchMany(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonFirstByContains(db.getConn(), TEST_TABLE, Map.of("value", "purple"));
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertTrue(json.contains(JsonDocument.four) || json.contains(JsonDocument.five),
+                        String.format("Expected document 'four' or 'five' (%s)", json));
+                break;
+            case POSTGRESQL:
+                assertTrue(json.contains(docId("four")) || json.contains(docId("five")),
+                        String.format("Expected document 'four' or 'five' (%s)", json));
+                break;
+        }
+    }
+
+    public static void firstByContainsMatchOrdered(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonFirstByContains(db.getConn(), TEST_TABLE, Map.of("value", "purple"),
+                List.of(Field.named("sub.bar NULLS FIRST")));
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertEquals(JsonDocument.five, json, "An incorrect document was returned");
+                break;
+            case POSTGRESQL:
+                assertTrue(json.contains(docId("five")),
+                        String.format("An incorrect document was returned (%s)", json));
+                break;
+        }
+    }
+
+    public static void firstByContainsNoMatch(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        assertEquals("{}", jsonFirstByContains(db.getConn(), TEST_TABLE, Map.of("value", "indigo")),
+                "There should have been no document returned");
+    }
+
+    public static void firstByJsonPathMatchOne(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonFirstByJsonPath(db.getConn(), TEST_TABLE, "$.numValue ? (@ == 10)");
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertEquals(JsonDocument.two, json, "An incorrect document was returned");
+                break;
+            case POSTGRESQL:
+                assertTrue(json.contains(docId("two")), String.format("An incorrect document was returned (%s)", json));
+                break;
+        }
+    }
+
+    public static void firstByJsonPathMatchMany(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonFirstByJsonPath(db.getConn(), TEST_TABLE, "$.numValue ? (@ > 10)");
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertTrue(json.contains(JsonDocument.four) || json.contains(JsonDocument.five),
+                        String.format("Expected document 'four' or 'five' (%s)", json));
+                break;
+            case POSTGRESQL:
+                assertTrue(json.contains(docId("four")) || json.contains(docId("five")),
+                        String.format("Expected document 'four' or 'five' (%s)", json));
+                break;
+        }
+    }
+
+    public static void firstByJsonPathMatchOrdered(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        final String json = jsonFirstByJsonPath(db.getConn(), TEST_TABLE, "$.numValue ? (@ > 10)",
+                List.of(Field.named("id DESC")));
+        switch (Configuration.dialect()) {
+            case SQLITE:
+                assertEquals(JsonDocument.four, json, "An incorrect document was returned");
+                break;
+            case POSTGRESQL:
+                assertTrue(json.contains(docId("four")),
+                        String.format("An incorrect document was returned (%s)", json));
+                break;
+        }
+    }
+
+    public static void firstByJsonPathNoMatch(ThrowawayDatabase db) throws DocumentException {
+        JsonDocument.load(db);
+        assertEquals("{}", jsonFirstByJsonPath(db.getConn(), TEST_TABLE, "$.numValue ? (@ > 100)"),
+                "There should have been no document returned");
     }
 }
diff --git a/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/NumIdDocument.java b/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/NumIdDocument.java
index f980c09..3d4ea66 100644
--- a/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/NumIdDocument.java
+++ b/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/NumIdDocument.java
@@ -3,7 +3,7 @@ package solutions.bitbadger.documents.core.tests.java.integration;
 public class NumIdDocument {
 
     private int key;
-    private String value;
+    private String text;
 
     public int getKey() {
         return key;
@@ -13,17 +13,17 @@ public class NumIdDocument {
         this.key = key;
     }
 
-    public String getValue() {
-        return value;
+    public String getText() {
+        return text;
     }
 
-    public void setValue(String value) {
-        this.value = value;
+    public void setText(String text) {
+        this.text = text;
     }
 
-    public NumIdDocument(int key, String value) {
+    public NumIdDocument(int key, String text) {
         this.key = key;
-        this.value = value;
+        this.text = text;
     }
 
     public NumIdDocument() {
diff --git a/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/PostgreSQLJsonIT.java b/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/PostgreSQLJsonIT.java
new file mode 100644
index 0000000..c8129a5
--- /dev/null
+++ b/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/PostgreSQLJsonIT.java
@@ -0,0 +1,245 @@
+package solutions.bitbadger.documents.core.tests.java.integration;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import solutions.bitbadger.documents.DocumentException;
+import solutions.bitbadger.documents.core.tests.integration.PgDB;
+
+/**
+ * PostgreSQL integration tests for the `Json` object / `json*` connection extension functions
+ */
+@DisplayName("Core | Java | PostgreSQL: Json")
+final public class PostgreSQLJsonIT {
+
+    @Test
+    @DisplayName("all retrieves all documents")
+    public void allDefault() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.allDefault(db);
+        }
+    }
+
+    @Test
+    @DisplayName("all succeeds with an empty table")
+    public void allEmpty() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.allEmpty(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byId retrieves a document via a string ID")
+    public void byIdString() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.byIdString(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byId retrieves a document via a numeric ID")
+    public void byIdNumber() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.byIdNumber(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byId returns null when a matching ID is not found")
+    public void byIdNotFound() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.byIdNotFound(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byFields retrieves matching documents")
+    public void byFieldsMatch() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.byFieldsMatch(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byFields retrieves ordered matching documents")
+    public void byFieldsMatchOrdered() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.byFieldsMatchOrdered(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byFields retrieves matching documents with a numeric IN clause")
+    public void byFieldsMatchNumIn() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.byFieldsMatchNumIn(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byFields succeeds when no documents match")
+    public void byFieldsNoMatch() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.byFieldsNoMatch(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byFields retrieves matching documents with an IN_ARRAY comparison")
+    public void byFieldsMatchInArray() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.byFieldsMatchInArray(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byFields succeeds when no documents match an IN_ARRAY comparison")
+    public void byFieldsNoMatchInArray() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.byFieldsNoMatchInArray(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byContains retrieves matching documents")
+    public void byContainsMatch() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.byContainsMatch(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byContains retrieves ordered matching documents")
+    public void byContainsMatchOrdered() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.byContainsMatchOrdered(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byContains succeeds when no documents match")
+    public void byContainsNoMatch() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.byContainsNoMatch(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byJsonPath retrieves matching documents")
+    public void byJsonPathMatch() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.byJsonPathMatch(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byJsonPath retrieves ordered matching documents")
+    public void byJsonPathMatchOrdered() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.byJsonPathMatchOrdered(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byJsonPath succeeds when no documents match")
+    public void byJsonPathNoMatch() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.byJsonPathNoMatch(db);
+        }
+    }
+
+    @Test
+    @DisplayName("firstByFields retrieves a matching document")
+    public void firstByFieldsMatchOne() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.firstByFieldsMatchOne(db);
+        }
+    }
+
+    @Test
+    @DisplayName("firstByFields retrieves a matching document among many")
+    public void firstByFieldsMatchMany() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.firstByFieldsMatchMany(db);
+        }
+    }
+
+    @Test
+    @DisplayName("firstByFields retrieves a matching document among many (ordered)")
+    public void firstByFieldsMatchOrdered() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.firstByFieldsMatchOrdered(db);
+        }
+    }
+
+    @Test
+    @DisplayName("firstByFields returns null when no document matches")
+    public void firstByFieldsNoMatch() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.firstByFieldsNoMatch(db);
+        }
+    }
+
+    @Test
+    @DisplayName("firstByContains retrieves a matching document")
+    public void firstByContainsMatchOne() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.firstByContainsMatchOne(db);
+        }
+    }
+
+    @Test
+    @DisplayName("firstByContains retrieves a matching document among many")
+    public void firstByContainsMatchMany() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.firstByContainsMatchMany(db);
+        }
+    }
+
+    @Test
+    @DisplayName("firstByContains retrieves a matching document among many (ordered)")
+    public void firstByContainsMatchOrdered() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.firstByContainsMatchOrdered(db);
+        }
+    }
+
+    @Test
+    @DisplayName("firstByContains returns null when no document matches")
+    public void firstByContainsNoMatch() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.firstByContainsNoMatch(db);
+        }
+    }
+
+    @Test
+    @DisplayName("firstByJsonPath retrieves a matching document")
+    public void firstByJsonPathMatchOne() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.firstByJsonPathMatchOne(db);
+        }
+    }
+
+    @Test
+    @DisplayName("firstByJsonPath retrieves a matching document among many")
+    public void firstByJsonPathMatchMany() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.firstByJsonPathMatchMany(db);
+        }
+    }
+
+    @Test
+    @DisplayName("firstByJsonPath retrieves a matching document among many (ordered)")
+    public void firstByJsonPathMatchOrdered() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.firstByJsonPathMatchOrdered(db);
+        }
+    }
+
+    @Test
+    @DisplayName("firstByJsonPath returns null when no document matches")
+    public void firstByJsonPathNoMatch() throws DocumentException {
+        try (PgDB db = new PgDB()) {
+            JsonFunctions.firstByJsonPathNoMatch(db);
+        }
+    }
+}
diff --git a/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/SQLiteJsonIT.java b/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/SQLiteJsonIT.java
new file mode 100644
index 0000000..1b3d447
--- /dev/null
+++ b/src/core/src/test/java/solutions/bitbadger/documents/core/tests/java/integration/SQLiteJsonIT.java
@@ -0,0 +1,167 @@
+package solutions.bitbadger.documents.core.tests.java.integration;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import solutions.bitbadger.documents.DocumentException;
+import solutions.bitbadger.documents.core.tests.integration.SQLiteDB;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+/**
+ * SQLite integration tests for the `Json` object / `json*` connection extension functions
+ */
+@DisplayName("Core | Java | SQLite: Json")
+final public class SQLiteJsonIT {
+
+    @Test
+    @DisplayName("all retrieves all documents")
+    public void allDefault() throws DocumentException {
+        try (SQLiteDB db = new SQLiteDB()) {
+            JsonFunctions.allDefault(db);
+        }
+    }
+
+    @Test
+    @DisplayName("all succeeds with an empty table")
+    public void allEmpty() throws DocumentException {
+        try (SQLiteDB db = new SQLiteDB()) {
+            JsonFunctions.allEmpty(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byId retrieves a document via a string ID")
+    public void byIdString() throws DocumentException {
+        try (SQLiteDB db = new SQLiteDB()) {
+            JsonFunctions.byIdString(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byId retrieves a document via a numeric ID")
+    public void byIdNumber() throws DocumentException {
+        try (SQLiteDB db = new SQLiteDB()) {
+            JsonFunctions.byIdNumber(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byId returns null when a matching ID is not found")
+    public void byIdNotFound() throws DocumentException {
+        try (SQLiteDB db = new SQLiteDB()) {
+            JsonFunctions.byIdNotFound(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byFields retrieves matching documents")
+    public void byFieldsMatch() throws DocumentException {
+        try (SQLiteDB db = new SQLiteDB()) {
+            JsonFunctions.byFieldsMatch(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byFields retrieves ordered matching documents")
+    public void byFieldsMatchOrdered() throws DocumentException {
+        try (SQLiteDB db = new SQLiteDB()) {
+            JsonFunctions.byFieldsMatchOrdered(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byFields retrieves matching documents with a numeric IN clause")
+    public void byFieldsMatchNumIn() throws DocumentException {
+        try (SQLiteDB db = new SQLiteDB()) {
+            JsonFunctions.byFieldsMatchNumIn(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byFields succeeds when no documents match")
+    public void byFieldsNoMatch() throws DocumentException {
+        try (SQLiteDB db = new SQLiteDB()) {
+            JsonFunctions.byFieldsNoMatch(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byFields retrieves matching documents with an IN_ARRAY comparison")
+    public void byFieldsMatchInArray() throws DocumentException {
+        try (SQLiteDB db = new SQLiteDB()) {
+            JsonFunctions.byFieldsMatchInArray(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byFields succeeds when no documents match an IN_ARRAY comparison")
+    public void byFieldsNoMatchInArray() throws DocumentException {
+        try (SQLiteDB db = new SQLiteDB()) {
+            JsonFunctions.byFieldsNoMatchInArray(db);
+        }
+    }
+
+    @Test
+    @DisplayName("byContains fails")
+    public void byContainsFails() {
+        try (SQLiteDB db = new SQLiteDB()) {
+            assertThrows(DocumentException.class, () -> JsonFunctions.byContainsMatch(db));
+        }
+    }
+
+    @Test
+    @DisplayName("byJsonPath fails")
+    public void byJsonPathFails() {
+        try (SQLiteDB db = new SQLiteDB()) {
+            assertThrows(DocumentException.class, () -> JsonFunctions.byJsonPathMatch(db));
+        }
+    }
+
+    @Test
+    @DisplayName("firstByFields retrieves a matching document")
+    public void firstByFieldsMatchOne() throws DocumentException {
+        try (SQLiteDB db = new SQLiteDB()) {
+            JsonFunctions.firstByFieldsMatchOne(db);
+        }
+    }
+
+    @Test
+    @DisplayName("firstByFields retrieves a matching document among many")
+    public void firstByFieldsMatchMany() throws DocumentException {
+        try (SQLiteDB db = new SQLiteDB()) {
+            JsonFunctions.firstByFieldsMatchMany(db);
+        }
+    }
+
+    @Test
+    @DisplayName("firstByFields retrieves a matching document among many (ordered)")
+    public void firstByFieldsMatchOrdered() throws DocumentException {
+        try (SQLiteDB db = new SQLiteDB()) {
+            JsonFunctions.firstByFieldsMatchOrdered(db);
+        }
+    }
+
+    @Test
+    @DisplayName("firstByFields returns null when no document matches")
+    public void firstByFieldsNoMatch() throws DocumentException {
+        try (SQLiteDB db = new SQLiteDB()) {
+            JsonFunctions.firstByFieldsNoMatch(db);
+        }
+    }
+
+    @Test
+    @DisplayName("firstByContains fails")
+    public void firstByContainsFails() {
+        try (SQLiteDB db = new SQLiteDB()) {
+            assertThrows(DocumentException.class, () -> JsonFunctions.firstByContainsMatchOne(db));
+        }
+    }
+
+    @Test
+    @DisplayName("firstByJsonPath fails")
+    public void firstByJsonPathFails() {
+        try (SQLiteDB db = new SQLiteDB()) {
+            assertThrows(DocumentException.class, () -> JsonFunctions.firstByJsonPathMatchOne(db));
+        }
+    }
+}
diff --git a/src/core/src/test/kotlin/integration/JsonFunctions.kt b/src/core/src/test/kotlin/integration/JsonFunctions.kt
index 77de5b8..94b23d4 100644
--- a/src/core/src/test/kotlin/integration/JsonFunctions.kt
+++ b/src/core/src/test/kotlin/integration/JsonFunctions.kt
@@ -58,11 +58,11 @@ object JsonFunctions {
                 assertTrue(json.contains(JsonDocument.five), "Document 'five' not found in JSON ($json)")
             }
             Dialect.POSTGRESQL -> {
-                assertTrue(json.indexOf(docId("one")) >= 0, "Document 'one' not found in JSON ($json)")
-                assertTrue(json.indexOf(docId("two")) >= 0, "Document 'two' not found in JSON ($json)")
-                assertTrue(json.indexOf(docId("three")) >= 0, "Document 'three' not found in JSON ($json)")
-                assertTrue(json.indexOf(docId("four")) >= 0, "Document 'four' not found in JSON ($json)")
-                assertTrue(json.indexOf(docId("five")) >= 0, "Document 'five' not found in JSON ($json)")
+                assertTrue(json.contains(docId("one")), "Document 'one' not found in JSON ($json)")
+                assertTrue(json.contains(docId("two")), "Document 'two' not found in JSON ($json)")
+                assertTrue(json.contains(docId("three")), "Document 'three' not found in JSON ($json)")
+                assertTrue(json.contains(docId("four")), "Document 'four' not found in JSON ($json)")
+                assertTrue(json.contains(docId("five")), "Document 'five' not found in JSON ($json)")
             }
         }
         assertTrue(json.endsWith("]"), "JSON should end with ']' ($json)")
@@ -76,10 +76,7 @@ object JsonFunctions {
         val json = db.conn.jsonById(TEST_TABLE, "two")
         when (Configuration.dialect()) {
             Dialect.SQLITE -> assertEquals(JsonDocument.two, json, "An incorrect document was returned")
-            Dialect.POSTGRESQL -> assertTrue(
-                json.indexOf(docId("two")) >= 0,
-                "An incorrect document was returned ($json)"
-            )
+            Dialect.POSTGRESQL -> assertTrue(json.contains(docId("two")), "An incorrect document was returned ($json)")
         }
     }