diff --git a/src/common/pom.xml b/src/common/pom.xml
index 2bc4cdc..110ad24 100644
--- a/src/common/pom.xml
+++ b/src/common/pom.xml
@@ -66,6 +66,12 @@
     </build>
 
     <dependencies>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.11.1</version>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.jetbrains.kotlin</groupId>
             <artifactId>kotlin-test-junit5</artifactId>
diff --git a/src/common/src/main/kotlin/Op.kt b/src/common/src/main/kotlin/Op.kt
index 0fbf185..89f6139 100644
--- a/src/common/src/main/kotlin/Op.kt
+++ b/src/common/src/main/kotlin/Op.kt
@@ -3,7 +3,7 @@ package solutions.bitbadger.documents.common
 /**
  * A comparison operator used for fields
  */
-enum class Op(sql: String) {
+enum class Op(val sql: String) {
     /** Compare using equality */
     EQUAL("="),
     /** Compare using greater-than */
diff --git a/src/common/src/test/kotlin/AutoIdTest.kt b/src/common/src/test/kotlin/AutoIdTest.kt
new file mode 100644
index 0000000..9552a81
--- /dev/null
+++ b/src/common/src/test/kotlin/AutoIdTest.kt
@@ -0,0 +1,17 @@
+package solutions.bitbadger.documents.common
+
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNotNull
+
+class AutoIdTest {
+
+    @Test
+    @DisplayName("Generates a UUID string")
+    fun testGenerateUUID() {
+        val generated = AutoId.generateUUID()
+        assertNotNull(generated, "The UUID string should not have been null")
+        assertEquals(32, generated.length, "The UUID should have been a 32-character string")
+    }
+}
\ No newline at end of file
diff --git a/src/common/src/test/kotlin/FieldTest.kt b/src/common/src/test/kotlin/FieldTest.kt
new file mode 100644
index 0000000..9a74bae
--- /dev/null
+++ b/src/common/src/test/kotlin/FieldTest.kt
@@ -0,0 +1,20 @@
+package solutions.bitbadger.documents.common
+
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNull
+
+class FieldTest {
+
+    @Test
+    @DisplayName("Equal constructs a field")
+    fun equalCtor() {
+        val field = Field.Equal("Test", 14)
+        assertEquals("Test", field.name, "Field name not filled correctly")
+        assertEquals(Op.EQUAL, field.comparison.op, "Field comparison operation not filled correctly")
+        assertEquals(14, field.comparison.value, "Field comparison value not filled correctly")
+        assertNull(field.parameterName, "The parameter name should have been null")
+        assertNull(field.qualifier, "The qualifier should have been null")
+    }
+}
diff --git a/src/common/src/test/kotlin/OpTest.kt b/src/common/src/test/kotlin/OpTest.kt
new file mode 100644
index 0000000..6656928
--- /dev/null
+++ b/src/common/src/test/kotlin/OpTest.kt
@@ -0,0 +1,74 @@
+package solutions.bitbadger.documents.common
+
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+import kotlin.test.assertEquals
+
+class OpTest {
+
+    @Test
+    @DisplayName("EQUAL uses proper SQL")
+    fun equalSQL() {
+        assertEquals("=", Op.EQUAL.sql, "The SQL for equal is incorrect")
+    }
+
+    @Test
+    @DisplayName("GREATER uses proper SQL")
+    fun greaterSQL() {
+        assertEquals(">", Op.GREATER.sql, "The SQL for greater is incorrect")
+    }
+
+    @Test
+    @DisplayName("GREATER_OR_EQUAL uses proper SQL")
+    fun greaterOrEqualSQL() {
+        assertEquals(">=", Op.GREATER_OR_EQUAL.sql, "The SQL for greater-or-equal is incorrect")
+    }
+
+    @Test
+    @DisplayName("LESS uses proper SQL")
+    fun lessSQL() {
+        assertEquals("<", Op.LESS.sql, "The SQL for less is incorrect")
+    }
+
+    @Test
+    @DisplayName("LESS_OR_EQUAL uses proper SQL")
+    fun lessOrEqualSQL() {
+        assertEquals("<=", Op.LESS_OR_EQUAL.sql, "The SQL for less-or-equal is incorrect")
+    }
+
+    @Test
+    @DisplayName("NOT_EQUAL uses proper SQL")
+    fun notEqualSQL() {
+        assertEquals("<>", Op.NOT_EQUAL.sql, "The SQL for not-equal is incorrect")
+    }
+
+    @Test
+    @DisplayName("BETWEEN uses proper SQL")
+    fun betweenSQL() {
+        assertEquals("BETWEEN", Op.BETWEEN.sql, "The SQL for between is incorrect")
+    }
+
+    @Test
+    @DisplayName("IN uses proper SQL")
+    fun inSQL() {
+        assertEquals("IN", Op.IN.sql, "The SQL for in is incorrect")
+    }
+
+    @Test
+    @DisplayName("IN_ARRAY uses proper SQL")
+    fun inArraySQL() {
+        assertEquals("?|", Op.IN_ARRAY.sql, "The SQL for in-array is incorrect")
+    }
+
+    @Test
+    @DisplayName("EXISTS uses proper SQL")
+    fun existsSQL() {
+        assertEquals("IS NOT NULL", Op.EXISTS.sql, "The SQL for exists is incorrect")
+    }
+
+    @Test
+    @DisplayName("NOT_EXISTS uses proper SQL")
+    fun notExistsSQL() {
+        assertEquals("IS NULL", Op.NOT_EXISTS.sql, "The SQL for not-exists is incorrect")
+    }
+}