diff --git a/src/test/java/com/datadoghq/trace/impl/SpanBuilderTest.java b/src/test/java/com/datadoghq/trace/impl/SpanBuilderTest.java
new file mode 100644
index 0000000000..d60f5b7d4e
--- /dev/null
+++ b/src/test/java/com/datadoghq/trace/impl/SpanBuilderTest.java
@@ -0,0 +1,97 @@
+package com.datadoghq.trace.impl;
+
+import org.assertj.core.data.MapEntry;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.Collections;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.*;
+
+public class SpanBuilderTest {
+
+    Tracer tracer;
+
+    @Before
+    public void setUp() throws Exception {
+        tracer = new Tracer();
+    }
+
+
+    @After
+    public void tearDown() throws Exception {
+    }
+
+
+    @Test
+    public void shouldBuilSimpleSpan() {
+
+        final String expectedName = "fakeName";
+        Span span = (Span) tracer.buildSpan(expectedName).start();
+        assertThat(span.getOperationName()).isEqualTo(expectedName);
+    }
+
+    @Test
+    public void shouldBuildTaggedSpan() {
+
+        final String expectedName = "fakeName";
+        final Map tags = new HashMap<String, Object>() {
+            {
+                put("1", true);
+                put("2", "fakeString");
+                put("3", 42.0);
+            }
+        };
+
+        Span span = (Span) tracer
+                .buildSpan(expectedName)
+                .withTag("1", (Boolean) tags.get("1"))
+                .withTag("2", (String) tags.get("2"))
+                .withTag("3", (Number) tags.get("3"))
+                .start();
+
+        assertThat(span.getOperationName()).isEqualTo(expectedName);
+        assertThat(span.getTags()).containsAllEntriesOf(tags);
+
+        // with no tag provided
+
+        span = (Span) tracer
+                .buildSpan(expectedName)
+                .start();
+
+        assertThat(span.getTags()).isNotNull();
+        assertThat(span.getTags()).isEmpty();
+
+
+    }
+
+    @Test
+    public void shouldBuilSpanTimestampInNano() {
+
+        final long expectedTimestamp = 487517802L * 1000 * 1000;
+        final String expectedName = "fakeName";
+
+        Span span = (Span) tracer
+                .buildSpan(expectedName)
+                .withStartTimestamp(expectedTimestamp)
+                .start();
+
+        assertThat(span.getStartTime()).isEqualTo(expectedTimestamp);
+
+        // auto-timestamp in nanoseconds
+        long tick = System.nanoTime();
+        span = (Span) tracer
+                .buildSpan(expectedName)
+                .start();
+
+        // between now and now + 100ms
+        assertThat(span.getStartTime()).isBetween(tick, tick * 1000 * 100);
+
+    }
+
+
+}
\ No newline at end of file
diff --git a/src/test/java/com/datadoghq/trace/impl/SpanTest.java b/src/test/java/com/datadoghq/trace/impl/SpanTest.java
new file mode 100644
index 0000000000..1878b690ab
--- /dev/null
+++ b/src/test/java/com/datadoghq/trace/impl/SpanTest.java
@@ -0,0 +1,8 @@
+package com.datadoghq.trace.impl;
+
+import static org.junit.Assert.*;
+
+
+public class SpanTest {
+
+}
\ No newline at end of file
diff --git a/src/test/java/com/datadoghq/trace/impl/TracerTest.java b/src/test/java/com/datadoghq/trace/impl/TracerTest.java
new file mode 100644
index 0000000000..b571ee2fca
--- /dev/null
+++ b/src/test/java/com/datadoghq/trace/impl/TracerTest.java
@@ -0,0 +1,19 @@
+package com.datadoghq.trace.impl;
+
+
+import org.junit.Test;
+
+class TracerTest {
+    @Test
+    void buildSpan() {
+    }
+
+    @Test
+    void inject() {
+    }
+
+    @Test
+    void extract() {
+    }
+
+}
\ No newline at end of file