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      1 package com.google.inject.testing.throwingproviders;
      2 
      3 import static com.google.common.truth.Truth.assertAbout;
      4 
      5 import com.google.common.truth.FailureMetadata;
      6 import com.google.common.truth.Subject;
      7 import com.google.common.truth.ThrowableSubject;
      8 import com.google.inject.throwingproviders.CheckedProvider;
      9 import javax.annotation.Nullable;
     10 
     11 /**
     12  * Truth {@link Subject} for use with {@link CheckedProvider} classes.
     13  *
     14  * @author eatnumber1 (at) google.com (Russ Harmon)
     15  */
     16 public final class CheckedProviderSubject<T, P extends CheckedProvider<T>>
     17     extends Subject<CheckedProviderSubject<T, P>, P> {
     18 
     19   private static final class CheckedProviderSubjectFactory<T, P extends CheckedProvider<T>>
     20       implements Subject.Factory<CheckedProviderSubject<T, P>, P> {
     21     @Override
     22     public CheckedProviderSubject<T, P> createSubject(
     23         FailureMetadata failureMetadata, @Nullable P target) {
     24       return new CheckedProviderSubject<T, P>(failureMetadata, target);
     25     }
     26   }
     27 
     28   public static <T, P extends CheckedProvider<T>>
     29       Subject.Factory<CheckedProviderSubject<T, P>, P> checkedProviders() {
     30     return new CheckedProviderSubjectFactory<>();
     31   }
     32 
     33   public static <T, P extends CheckedProvider<T>> CheckedProviderSubject<T, P> assertThat(
     34       @Nullable P provider) {
     35     return assertAbout(CheckedProviderSubject.<T, P>checkedProviders()).that(provider);
     36   }
     37 
     38   private CheckedProviderSubject(FailureMetadata failureMetadata, @Nullable P subject) {
     39     super(failureMetadata, subject);
     40   }
     41 
     42   /**
     43    * Allows for assertions on the value provided by this provider.
     44    *
     45    * <p>The value provided by a checked provider is the object returned by a call to {@link
     46    * CheckedProvider#get}
     47    *
     48    * @return a {@link Subject} for asserting against the return value of {@link CheckedProvider#get}
     49    */
     50   public Subject<?, Object> providedValue() {
     51     P provider = actual();
     52     T got;
     53     try {
     54       got = provider.get();
     55     } catch (Exception e) {
     56       failWithRawMessageAndCause(
     57           String.format("checked provider <%s> threw an exception", provider), e);
     58       return ignoreCheck().that(new Object());
     59     }
     60     return check().withMessage("value provided by <%s>", provider).that(got);
     61   }
     62 
     63   /**
     64    * Allows for assertions on the exception thrown by this provider.
     65    *
     66    * <p>The exception thrown by a checked provider is the {@link Throwable} thrown by a call to
     67    * {@link CheckedProvider#get}
     68    *
     69    * @return a {@link ThrowableSubject} for asserting against the {@link Throwable} thrown by {@link
     70    *     CheckedProvider#get}
     71    */
     72   public ThrowableSubject thrownException() {
     73     P provider = actual();
     74     T got;
     75     try {
     76       got = provider.get();
     77     } catch (Throwable e) {
     78       return check().withMessage("exception thrown by <%s>", provider).that(e);
     79     }
     80     failWithBadResults("threw", "an exception", "provided", got);
     81     return ignoreCheck().that(new Throwable());
     82   }
     83 }
     84