fix: #74 implement Wallet.File.key

src/main/java/io/zold/api/Wallet.java

@@ -70,8 +70,9 @@ public interface Wallet {
     /**
      * This wallet's RSA key.
      * @return This wallet's RSA key
+     * @throws IOException If an IO error occurs
      */
-    String key();
+    String key() throws IOException;
 
     /**
      * A Fake {@link Wallet}.
@@ -275,14 +276,19 @@ public Iterable<Transaction> ledger() {
             );
         }
 
-        // @todo #54:30min Implement key method. This should return the
-        //  public RSA key of the wallet owner in Base64. Also add a unit test
-        //  to replace WalletTest.keyIsNotYetImplemented().
         @Override
-        public String key() {
-            throw new UnsupportedOperationException(
-                "key() not yet supported"
-            );
+        public String key() throws IOException {
+            // @checkstyle ProhibitLineSeparatorInStringsCheck (10 lines)
+            return new Checked<>(
+                () -> new ListOf<>(
+                    new Split(
+                        new TextOf(this.path),
+                        "\n"
+                    )
+                // @checkstyle MagicNumberCheck (1 line)
+                ).get(3).asString(),
+                e -> new IOException(e)
+            ).value();
         }
     }
 }

src/test/java/io/zold/api/WalletTest.java

@@ -195,11 +195,13 @@ public void walletShouldBeAbleToReturnLedger() throws Exception {
     }
 
     @Test
-    public void keyIsNotYetImplemented() throws IOException {
-        final Path path = this.folder.newFile().toPath();
-        Assertions.assertThrows(
-            UnsupportedOperationException.class,
-            () -> new Wallet.File(path).key()
+    public void readsPublicKey() throws IOException {
+        MatcherAssert.assertThat(
+            new Wallet.File(this.wallet(5_124_095_577_148_911L)).key(),
+            Matchers.is(
+                // @checkstyle LineLengthCheck (1 line)
+                "MIGeMA0GCSqGSIb3DQEBAQUAA4GMADCBiAKBgGZCr/9hBChqsChd4sRAIpKNRinjhSW+J+S7PU5malVMiRHVoKjeooLDpWpij0A6vkzOvjrMldAZT0Fzgp0cJ15TOVwiQanQ5WuQDgRkLoxrdh/qyBApoDvk4OUEozOQPNwfpZOFfaUALPsPnv9995TlY9WcdSKW5dj041p1tJmlAgMBAAE="
+            )
         );
     }