Make StringSubject.matches suggest using containsMatch if matches(x) fails but containsMatch(x) would have passed.

Fixes #791

Fixes #830

RELNOTES=Improved the failure message for `matches` to conditionally suggest using `containsMatch`.
COPYBARA_INTEGRATE_REVIEW=#830 from junyan59:stringMatches cc02dca
PiperOrigin-RevId: 647435705

Author: junyan59

core/src/main/java/com/google/common/truth/StringSubject.java

@@ -129,6 +129,11 @@ public void matches(@Nullable String regex) {
             fact("expected to match", regex),
             fact("but was", actual),
             simpleFact("Looks like you want to use .isEqualTo() for an exact equality assertion."));
+      } else if (Platform.containsMatch(actual, regex)) {
+        failWithoutActual(
+            fact("expected to match", regex),
+            fact("but was", actual),
+            simpleFact("Did you mean to call containsMatch() instead of match()?"));
       } else {
         failWithActual("expected to match", regex);
       }
@@ -149,6 +154,11 @@ public void matches(@Nullable Pattern regex) {
             simpleFact(
                 "If you want an exact equality assertion you can escape your regex with"
                     + " Pattern.quote()."));
+      } else if (regex.matcher(actual).find()) {
+        failWithoutActual(
+            fact("expected to match", regex),
+            fact("but was", actual),
+            simpleFact("Did you mean to call containsMatch() instead of match()?"));
       } else {
         failWithActual("expected to match", regex);
       }

core/src/test/java/com/google/common/truth/StringSubjectTest.java

@@ -216,6 +216,16 @@ public void stringMatchesStringLiteralFail() {
         .contains("Looks like you want to use .isEqualTo() for an exact equality assertion.");
   }
 
+  @Test
+  public void stringMatchesStringLiteralFailButContainsMatchSuccess() {
+    expectFailureWhenTestingThat("aba").matches("[b]");
+    assertFailureValue("expected to match", "[b]");
+    assertFailureValue("but was", "aba");
+    assertThat(expectFailure.getFailure())
+        .factKeys()
+        .contains("Did you mean to call containsMatch() instead of match()?");
+  }
+
   @Test
   @GwtIncompatible("Pattern")
   public void stringMatchesPattern() {
@@ -249,6 +259,17 @@ public void stringMatchesPatternLiteralFail() {
                 + " Pattern.quote().");
   }
 
+  @Test
+  @GwtIncompatible("Pattern")
+  public void stringMatchesPatternLiteralFailButContainsMatchSuccess() {
+    expectFailureWhenTestingThat("aba").matches(Pattern.compile("[b]"));
+    assertFailureValue("expected to match", "[b]");
+    assertFailureValue("but was", "aba");
+    assertThat(expectFailure.getFailure())
+        .factKeys()
+        .contains("Did you mean to call containsMatch() instead of match()?");
+  }
+
   @Test
   public void stringDoesNotMatchString() {
     assertThat("abcaqadev").doesNotMatch(".*aaa.*");