diff --git a/test/interface/bigdata.go b/test/interface/bigdata.go
index 0d8c408c817..0f2e9a990ec 100644
--- a/test/interface/bigdata.go
+++ b/test/interface/bigdata.go
@@ -4,8 +4,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// check that big vs small, pointer vs not
-// interface methods work.
+// Test big vs. small, pointer vs. value interface methods.
 
 package main
 
diff --git a/test/interface/convert.go b/test/interface/convert.go
index 2b4f45d14f0..eb6fd1d5542 100644
--- a/test/interface/convert.go
+++ b/test/interface/convert.go
@@ -4,8 +4,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Check uses of all the different interface
-// conversion runtime functions.
+// Test all the different interface conversion runtime functions.
 
 package main
 
diff --git a/test/interface/convert1.go b/test/interface/convert1.go
index 4833e847a24..4a3ec8a375d 100644
--- a/test/interface/convert1.go
+++ b/test/interface/convert1.go
@@ -4,8 +4,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Check that static interface conversion of
-// interface value nil succeeds.
+// Test static interface conversion of interface value nil.
 
 package main
 
diff --git a/test/interface/convert2.go b/test/interface/convert2.go
index 4833e847a24..4a3ec8a375d 100644
--- a/test/interface/convert2.go
+++ b/test/interface/convert2.go
@@ -4,8 +4,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Check that static interface conversion of
-// interface value nil succeeds.
+// Test static interface conversion of interface value nil.
 
 package main
 
diff --git a/test/interface/embed.go b/test/interface/embed.go
index 46c02cc80e4..5c52ac02323 100644
--- a/test/interface/embed.go
+++ b/test/interface/embed.go
@@ -4,7 +4,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Check methods derived from embedded interface values.
+// Test methods derived from embedded interface values.
 
 package main
 
diff --git a/test/interface/embed0.go b/test/interface/embed0.go
index bbd81e76038..dee8319e4e9 100644
--- a/test/interface/embed0.go
+++ b/test/interface/embed0.go
@@ -4,7 +4,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Check that embedded interface types can have local methods.
+// Test that embedded interface types can have local methods.
 
 package p
 
diff --git a/test/interface/embed1.go b/test/interface/embed1.go
index 24e50471f2d..ee502a162fc 100644
--- a/test/interface/embed1.go
+++ b/test/interface/embed1.go
@@ -4,7 +4,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Check that embedded interface types can have local methods.
+// Test that embedded interface types can have local methods.
 
 package main
 
diff --git a/test/interface/embed2.go b/test/interface/embed2.go
index bac214397ab..1636db78eb8 100644
--- a/test/interface/embed2.go
+++ b/test/interface/embed2.go
@@ -4,7 +4,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Check methods derived from embedded interface and *interface values.
+// Test methods derived from embedded interface and *interface values.
 
 package main
 
diff --git a/test/interface/explicit.go b/test/interface/explicit.go
index fbe65e7e399..d19480a6856 100644
--- a/test/interface/explicit.go
+++ b/test/interface/explicit.go
@@ -4,7 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Static error messages about interface conversions.
+// Verify compiler messages about erroneous static interface conversions.
+// Does not compile.
 
 package main
 
diff --git a/test/interface/fail.go b/test/interface/fail.go
index 5a2f57fe9f4..72b854dc00c 100644
--- a/test/interface/fail.go
+++ b/test/interface/fail.go
@@ -4,7 +4,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Check that interface conversion fails when method is missing.
+// Test that interface conversion fails when method is missing.
 
 package main
 
diff --git a/test/interface/fake.go b/test/interface/fake.go
index 55650cc8dd5..861a640842f 100644
--- a/test/interface/fake.go
+++ b/test/interface/fake.go
@@ -4,7 +4,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Interface comparisons using types hidden
+// Test interface comparisons using types hidden
 // inside reflected-on structs.
 
 package main
diff --git a/test/interface/noeq.go b/test/interface/noeq.go
index b89fd0e8248..1c5166ededf 100644
--- a/test/interface/noeq.go
+++ b/test/interface/noeq.go
@@ -4,7 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Interface values containing types that cannot be compared for equality.
+// Test run-time error detection for interface values containing types
+// that cannot be compared for equality.
 
 package main
 
diff --git a/test/interface/pointer.go b/test/interface/pointer.go
index 0548c240463..2927050669a 100644
--- a/test/interface/pointer.go
+++ b/test/interface/pointer.go
@@ -4,7 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Check that interface{M()} = *interface{M()} produces a compiler error.
+// Test that interface{M()} = *interface{M()} produces a compiler error.
+// Does not compile.
 
 package main
 
diff --git a/test/interface/private.go b/test/interface/private.go
index 37890c923a5..14dfc1ae554 100644
--- a/test/interface/private.go
+++ b/test/interface/private.go
@@ -4,6 +4,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Test that unexported methods are not visible outside the package.
+// Does not compile.
+
 package main
 
 import "./private1"
diff --git a/test/interface/private1.go b/test/interface/private1.go
index 3173fbef41f..9c831a2f477 100644
--- a/test/interface/private1.go
+++ b/test/interface/private1.go
@@ -4,6 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Imported by private.go, which should not be able to see the private method.
+
 package p
 
 type Exported interface {
diff --git a/test/interface/receiver.go b/test/interface/receiver.go
index dc2e7808f7a..4511ab3b473 100644
--- a/test/interface/receiver.go
+++ b/test/interface/receiver.go
@@ -4,8 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Implicit methods for embedded types.
-// Mixed pointer and non-pointer receivers.
+// Test Implicit methods for embedded types and
+// mixed pointer and non-pointer receivers.
 
 package main
 
diff --git a/test/interface/receiver1.go b/test/interface/receiver1.go
index 19ca6d46261..2b7ccdc1a7b 100644
--- a/test/interface/receiver1.go
+++ b/test/interface/receiver1.go
@@ -4,7 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Error messages about missing implicit methods.
+// Verify compiler complains about missing implicit methods.
+// Does not compile.
 
 package main
 
diff --git a/test/interface/recursive1.go b/test/interface/recursive1.go
index 2c93a28363a..524dda82c6f 100644
--- a/test/interface/recursive1.go
+++ b/test/interface/recursive1.go
@@ -4,6 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Mutually recursive type definitions imported and used by recursive1.go.
+
 package p
 
 type I1 interface {
diff --git a/test/interface/recursive2.go b/test/interface/recursive2.go
index a7f9ab5dbd9..5129ceb022d 100644
--- a/test/interface/recursive2.go
+++ b/test/interface/recursive2.go
@@ -4,7 +4,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Check that the mutually recursive types in recursive1.go made it
+// Test that the mutually recursive types in recursive1.go made it
 // intact and with the same meaning, by assigning to or using them.
 
 package main
diff --git a/test/interface/returntype.go b/test/interface/returntype.go
index b7bebe4f61c..4d86f391840 100644
--- a/test/interface/returntype.go
+++ b/test/interface/returntype.go
@@ -4,7 +4,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Check methods with different return types.
+// Test interface methods with different return types are distinct.
 
 package main
 
diff --git a/test/interface/struct.go b/test/interface/struct.go
index 3c9d01da4a8..f60819ca811 100644
--- a/test/interface/struct.go
+++ b/test/interface/struct.go
@@ -4,7 +4,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Interface values containing structures.
+// Test interface values containing structures.
 
 package main