diff --git a/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/go.mod b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/go.mod
new file mode 100644
index 00000000000..709117ebc26
--- /dev/null
+++ b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/go.mod
@@ -0,0 +1,5 @@
+module semmle.go.Packages
+
+go 1.13
+
+require github.com/nonexistent-test-pkg v0.0.0-20200203000000-0000000000000
diff --git a/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/sinks.expected b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/sinks.expected
new file mode 100644
index 00000000000..de1751aea90
--- /dev/null
+++ b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/sinks.expected
@@ -0,0 +1,3 @@
+invalidModelRow
+#select
+| test.go:40:10:40:12 | arg | qltest |
diff --git a/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/sinks.ql b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/sinks.ql
new file mode 100644
index 00000000000..ef8af3a321c
--- /dev/null
+++ b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/sinks.ql
@@ -0,0 +1,19 @@
+import go
+import semmle.go.dataflow.DataFlow
+import semmle.go.dataflow.ExternalFlow
+import CsvValidation
+
+class SinkModelTest extends SinkModelCsv {
+  override predicate row(string row) {
+    row =
+      [
+        //`namespace; type; subtypes; name; -; ext; input; kind`
+        "github.com/nonexistent/test;B;false;Sink1;;;Argument[0];qltest",
+        "github.com/nonexistent/test;B;false;SinkMethod;;;ReturnValue;qltest"
+      ]
+  }
+}
+
+from DataFlow::Node node, string kind
+where sinkNode(node, kind)
+select node, kind
diff --git a/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/srcs.expected b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/srcs.expected
new file mode 100644
index 00000000000..1c9cfbdb953
--- /dev/null
+++ b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/srcs.expected
@@ -0,0 +1,11 @@
+invalidModelRow
+#select
+| test.go:11:6:11:8 | definition of arg | qltest-arg |
+| test.go:28:6:28:6 | definition of a | qltest-arg |
+| test.go:31:8:31:15 | call to Src1 | qltest |
+| test.go:32:8:32:15 | call to Src2 | qltest |
+| test.go:32:8:32:15 | call to Src2 | qltest-w-subtypes |
+| test.go:33:8:33:16 | call to Src2 | qltest-w-subtypes |
+| test.go:34:2:34:21 | ... = ...[0] | qltest |
+| test.go:34:2:34:21 | ... = ...[1] | qltest-w-subtypes |
+| test.go:35:2:35:22 | ... = ...[1] | qltest-w-subtypes |
diff --git a/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/srcs.ql b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/srcs.ql
new file mode 100644
index 00000000000..72e728271f9
--- /dev/null
+++ b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/srcs.ql
@@ -0,0 +1,23 @@
+import go
+import semmle.go.dataflow.DataFlow
+import semmle.go.dataflow.ExternalFlow
+import CsvValidation
+
+class SourceModelTest extends SourceModelCsv {
+  override predicate row(string row) {
+    row =
+      [
+        //`namespace; type; subtypes; name; -; ext; output; kind`
+        "github.com/nonexistent/test;A;false;Src1;;;ReturnValue;qltest",
+        "github.com/nonexistent/test;A;false;Src2;;;ReturnValue;qltest",
+        "github.com/nonexistent/test;A;true;Src2;;;ReturnValue;qltest-w-subtypes",
+        "github.com/nonexistent/test;A;false;SrcArg;;;Argument;qltest-arg",
+        "github.com/nonexistent/test;A;false;Src3;;;ReturnValue[0];qltest",
+        "github.com/nonexistent/test;A;true;Src3;;;ReturnValue[1];qltest-w-subtypes"
+      ]
+  }
+}
+
+from DataFlow::Node node, string kind
+where sourceNode(node, kind)
+select node, kind
diff --git a/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/steps.expected b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/steps.expected
new file mode 100644
index 00000000000..375470ab2a2
--- /dev/null
+++ b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/steps.expected
@@ -0,0 +1,9 @@
+invalidModelRow
+#select
+| test.go:16:23:16:25 | arg | test.go:16:10:16:26 | call to StepArgRes |
+| test.go:17:27:17:29 | arg | test.go:17:2:17:30 | ... = ...[1] |
+| test.go:18:15:18:17 | arg | test.go:12:6:12:9 | definition of arg1 |
+| test.go:19:16:19:18 | arg | test.go:13:6:13:6 | definition of t |
+| test.go:20:10:20:10 | t | test.go:20:10:20:24 | call to StepQualRes |
+| test.go:21:2:21:2 | t | test.go:11:6:11:8 | definition of arg |
+| test.go:22:32:22:34 | arg | test.go:22:10:22:35 | call to StepArgResNoQual |
diff --git a/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/steps.ql b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/steps.ql
new file mode 100644
index 00000000000..11662dbab04
--- /dev/null
+++ b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/steps.ql
@@ -0,0 +1,27 @@
+import go
+import semmle.go.dataflow.DataFlow
+import semmle.go.dataflow.ExternalFlow
+import semmle.go.dataflow.internal.FlowSummaryImpl as FlowSummaryImpl
+import CsvValidation
+
+class SummaryModelTest extends SummaryModelCsv {
+  override predicate row(string row) {
+    row =
+      [
+        //`namespace; type; subtypes; name; -; ext; input; output; kind`
+        "github.com/nonexistent/test;T;false;StepArgRes;;;Argument[0];ReturnValue;taint",
+        "github.com/nonexistent/test;T;false;StepArgRes1;;;Argument[0];ReturnValue[1];taint",
+        "github.com/nonexistent/test;T;false;StepArgArg;;;Argument[0];Argument[1];taint",
+        "github.com/nonexistent/test;T;false;StepArgQual;;;Argument[0];Argument[-1];taint",
+        "github.com/nonexistent/test;T;false;StepQualRes;;;Argument[-1];ReturnValue;taint",
+        "github.com/nonexistent/test;T;false;StepQualArg;;;Argument[-1];Argument[0];taint",
+        "github.com/nonexistent/test;;false;StepArgResNoQual;;;Argument[0];ReturnValue;taint",
+        "github.com/nonexistent/test;;false;StepArgResContent;;;Argument[0];Element of ReturnValue;taint",
+        "github.com/nonexistent/test;;false;StepArgContentRes;;;ArrayElement of Argument[0];ReturnValue;taint"
+      ]
+  }
+}
+
+from DataFlow::Node node1, DataFlow::Node node2
+where FlowSummaryImpl::Private::Steps::summaryThroughStep(node1, node2, false)
+select node1, node2
diff --git a/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/test.go b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/test.go
new file mode 100644
index 00000000000..10a7141dcd0
--- /dev/null
+++ b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/test.go
@@ -0,0 +1,44 @@
+package main
+
+import (
+	"github.com/nonexistent/test"
+	"io"
+)
+
+func use(args ...interface{}) {}
+
+func main() {
+	var arg interface{}
+	var arg1 interface{}
+	var t *test.T
+	var taint interface{}
+
+	taint = t.StepArgRes(arg)
+	_, taint = t.StepArgRes1(arg)
+	t.StepArgArg(arg, arg1)
+	t.StepArgQual(arg)
+	taint = t.StepQualRes()
+	t.StepQualArg(arg)
+	taint = test.StepArgResNoQual(arg)
+	taint = test.StepArgResContent(arg)
+	taint = test.StepArgContentRes(arg)
+
+	var src interface{}
+	var src1 interface{}
+	var a test.A
+	var a1 test.A1
+
+	src = a.Src1()
+	src = a.Src2()
+	src = a1.Src2()
+	src, src1 = a.Src3()
+	src, src1 = a1.Src3()
+	a.SrcArg(arg)
+
+	var b test.B
+
+	b.Sink1(arg)
+	b.SinkMethod().(io.Writer).Write(arg.([]byte))
+
+	use(arg, arg1, t, taint, src, src1)
+}
diff --git a/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/vendor/github.com/nonexistent/test/stub.go b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/vendor/github.com/nonexistent/test/stub.go
new file mode 100644
index 00000000000..c083880da56
--- /dev/null
+++ b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/vendor/github.com/nonexistent/test/stub.go
@@ -0,0 +1,43 @@
+package test
+
+type T struct{}
+
+func (t *T) StepArgRes(arg interface{}) interface{} { return nil }
+
+func (t *T) StepArgRes1(arg interface{}) (interface{}, interface{}) { return nil, nil }
+
+func (t *T) StepArgArg(a1 interface{}, a2 interface{}) {}
+
+func (t *T) StepArgQual(arg interface{}) {}
+
+func (t *T) StepQualRes() interface{} { return nil }
+
+func (t *T) StepQualArg(arg interface{}) {}
+
+func StepArgResNoQual(arg interface{}) interface{} { return nil }
+
+func StepArgResContent(arg interface{}) []interface{} { return nil }
+
+func StepArgContentRes(arg interface{}) interface{} { return nil }
+
+type A interface {
+	Src1() interface{}
+	Src2() interface{}
+	Src3() (interface{}, interface{})
+	SrcArg(arg interface{})
+}
+
+type A1 struct{}
+
+func (a *A1) Src1() interface{} { return nil }
+
+func (a *A1) Src2() interface{} { return nil }
+
+func (a *A1) Src3() (interface{}, interface{}) { return nil, nil }
+
+func (a *A1) SrcArg(arg interface{}) {}
+
+type B interface {
+	Sink1(arg interface{})
+	SinkMethod() interface{}
+}
diff --git a/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/vendor/modules.txt b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/vendor/modules.txt
new file mode 100644
index 00000000000..e46a0af8429
--- /dev/null
+++ b/ql/test/library-tests/semmle/go/dataflow/ExternalFlow/vendor/modules.txt
@@ -0,0 +1,2 @@
+# github.com/nonexistent-test-pkg v0.0.0-20200203000000-0000000000000
+github.com/nonexistent-test-package