@@ -3,6 +3,7 @@ package main

 import (

 	"strings"

+	"github.com/docker/docker/pkg/integration/checker"

 	"github.com/go-check/check"

 )

@@ -22,9 +23,7 @@ func (s *DockerSuite) TestDiffFilenameShownInOutput(c *check.C) {

 			break

 		}

 	}

-	if !found {

-		c.Errorf("couldn't find the new file in docker diff's output: %v", out)

-	}

+	c.Assert(found, checker.True)

 }

 // test to ensure GH #3840 doesn't occur any more

@@ -43,9 +42,7 @@ func (s *DockerSuite) TestDiffEnsureDockerinitFilesAreIgnored(c *check.C) {

 		out, _ = dockerCmd(c, "diff", cleanCID)

 		for _, filename := range dockerinitFiles {

-			if strings.Contains(out, filename) {

-				c.Errorf("found file which should've been ignored %v in diff output", filename)

-			}

+			c.Assert(out, checker.Not(checker.Contains), filename)

 		}

 	}

 }

@@ -78,15 +75,13 @@ func (s *DockerSuite) TestDiffEnsureOnlyKmsgAndPtmx(c *check.C) {

 	}

 	for _, line := range strings.Split(out, "\n") {

-		if line != "" && !expected[line] {

-			c.Errorf("%q is shown in the diff but shouldn't", line)

-		}

+		c.Assert(line == "" || expected[line], checker.True)

 	}

 }

 // https://github.com/docker/docker/pull/14381#discussion_r33859347

 func (s *DockerSuite) TestDiffEmptyArgClientError(c *check.C) {

 	out, _, err := dockerCmdWithError("diff", "")

-	c.Assert(err, check.NotNil)

-	c.Assert(strings.TrimSpace(out), check.Equals, "Container name cannot be empty")

+	c.Assert(err, checker.NotNil)

+	c.Assert(strings.TrimSpace(out), checker.Equals, "Container name cannot be empty")

 }