Assertion fail message for string contains substring [duplicate]

Question

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AssertContains on strings in jUnit (7 answers)

Closed 6 years ago.

I have done a lot of functional testing on text outputs on text generating software lately, an find myself writing a lot of

assertTrue(actualString.contains(wantedString));

However, the message for when this fails is something non-descriptive like

Expected [true], but was [false]

An alternative is to include a custom fail message as

String failMsg = String.format("Wanted string to contain: %s, Actual string: %s", wantedString, actualString);
assertTrue(failMsg, actualString.contains(wantedString));

But it feels a bit tedious to do this manually all the time. Is there a better way?

Answer 1

Use hamcrest Matcher containsString()

// Hamcrest assertion
assertThat(person.getName(), containsString("myName"));

// Error Message
java.lang.AssertionError:
Expected: a string containing "myName"
     got: "some other name"

You can optional add an even more detail error message.

// Hamcrest assertion with custom error message
assertThat("my error message", person.getName(), containsString("myName"));

// Error Message
java.lang.AssertionError: my error message
Expected: a string containing "myName"
     got: "some other name"