feat(test): #87 added a new test for LockedFile (#110)

src/test/java/com/fasterxml/uuid/ext/LockedFileTest.java

@@ -0,0 +1,261 @@
+package com.fasterxml.uuid.ext;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.util.UUID;
+import java.util.concurrent.ThreadLocalRandom;
+
+import static com.fasterxml.uuid.ext.LockedFile.READ_ERROR;
+import static org.junit.Assert.*;
+
+public class LockedFileTest
+{
+    @Rule
+    public TemporaryFolder temporaryFolder = new TemporaryFolder();
+
+    @Test
+    public void constructor_givenNull_shouldThrowNullPointerException() throws IOException {
+        try {
+            new LockedFile(null);
+            fail("This should have thrown a null pointer exception");
+        } catch (NullPointerException nullPointerException) {
+            ; // good
+        }
+    }
+
+    @Test
+    public void constructor_givenEmptyFile_shouldLeaveFileAsIs() throws IOException {
+        // given
+        File emptyFile = temporaryFolder.newFile();
+
+        // when
+        new LockedFile(emptyFile);
+
+        // then
+        assertTrue(emptyFile.exists());
+        assertTrue(emptyFile.canRead());
+        assertTrue(emptyFile.canWrite());
+    }
+
+    @Test
+    public void constructor_givenNonExistentFile_shouldCreateANewFile() throws IOException {
+        // given
+        File blankFile = temporaryFolder.newFile();
+        File nonExistentFile = new File(blankFile + ".nonexistent");
+
+        if (Files.exists(nonExistentFile.toPath())) {
+            fail("temp file should not exist");
+        }
+
+        // when
+        new LockedFile(nonExistentFile);
+
+        // then - the nonexistent file now exists?
+        assertTrue(Files.exists(nonExistentFile.toPath()));
+        assertTrue(nonExistentFile.canRead());
+        assertTrue(nonExistentFile.canWrite());
+    }
+
+    @Test
+    public void constructor_canOnlyTakeAFile_shouldThrowFileNotFoundException() throws IOException {
+        // given
+        File blankFolder = temporaryFolder.newFolder();
+
+        // when
+        try {
+            new LockedFile(blankFolder);
+            fail("This should not succeed");
+        } catch (FileNotFoundException fileNotFoundException) {
+            // then
+            assertEquals(
+                    String.format("%s (Is a directory)", blankFolder.getPath()),
+                    fileNotFoundException.getMessage()
+            );
+        }
+    }
+
+    @Test
+    public void readStamp_givenEmptyFile_shouldReturnREADERROR() throws IOException {
+        // given
+        File emptyFile = temporaryFolder.newFile();
+
+        // when
+        LockedFile lockedFile = new LockedFile(emptyFile);
+        long stamp = lockedFile.readStamp();
+
+        // then
+        assertEquals(READ_ERROR, stamp);
+    }
+
+    @Test
+    public void readStamp_givenGibberishFile_shouldReturnREADERROR() throws IOException {
+        // given
+        File gibberishFile = temporaryFolder.newFile();
+        try(FileWriter fileWriter = new FileWriter(gibberishFile)) {
+            fileWriter.write(UUID.randomUUID().toString().substring(0, 22));
+            fileWriter.flush();
+        }
+
+        assertEquals(22, Files.size(gibberishFile.toPath()));
+
+        // when
+        LockedFile lockedFile = new LockedFile(gibberishFile);
+        long stamp = lockedFile.readStamp();
+
+        // then
+        assertEquals(READ_ERROR, stamp);
+    }
+
+    @Test
+    public void readStamp_givenTimestampedFile_shouldReturnValueInside() throws IOException {
+        // given
+        File timeStampedFile = temporaryFolder.newFile();
+        try(FileWriter fileWriter = new FileWriter(timeStampedFile)) {
+            // we are faking the timestamp format
+            fileWriter.write("[0x0000000000000001]");
+            fileWriter.flush();
+        }
+
+        // when
+        LockedFile lockedFile = new LockedFile(timeStampedFile);
+        long stamp = lockedFile.readStamp();
+
+        // then
+        long expectedTimestamp = 1;
+        assertEquals(expectedTimestamp, stamp);
+    }
+
+    // test for overflows
+    @Test
+    public void readStamp_givenOverflowedDigitFile_shouldReturnREADERROR() throws IOException {
+        // given
+        File timeStampedFile = temporaryFolder.newFile();
+        try(FileWriter fileWriter = new FileWriter(timeStampedFile)) {
+            // we are faking an overflowed timestamp
+            fileWriter.write("[0x10000000000000000]");
+            fileWriter.flush();
+        }
+
+        // when
+        LockedFile lockedFile = new LockedFile(timeStampedFile);
+        long stamp = lockedFile.readStamp();
+
+        // then
+        assertEquals(READ_ERROR, stamp);
+    }
+
+    @Test
+    public void readStamp_givenMaxLongFile_shouldReturnLargeTimestamp() throws IOException {
+        // given
+        File timeStampedFile = temporaryFolder.newFile();
+        try(FileWriter fileWriter = new FileWriter(timeStampedFile)) {
+            // we are faking an overflowed timestamp
+            fileWriter.write("[0x7fffffffffffffff]");
+            fileWriter.flush();
+        }
+
+        // when
+        LockedFile lockedFile = new LockedFile(timeStampedFile);
+        long stamp = lockedFile.readStamp();
+
+        // then
+        assertEquals(Long.MAX_VALUE, stamp);
+    }
+
+    @Test
+    public void writeStamp_givenNegativeTimestamps_shouldThrowIOException() throws IOException {
+        // given
+        File timeStampedFile = temporaryFolder.newFile();
+
+        // when
+        LockedFile lockedFile = new LockedFile(timeStampedFile);
+        try {
+            lockedFile.writeStamp(Long.MIN_VALUE);
+            fail("This should throw an exception");
+        } catch (IOException ioException) {
+            // then
+            assertTrue(ioException.getMessage().contains("trying to overwrite existing value"));
+            assertTrue(ioException.getMessage().contains("with an earlier timestamp"));
+        }
+    }
+
+    @Test
+    public void writeStamp_givenTimestampedFile_withLowerValue_shouldOverrideValue() throws IOException {
+        // given
+        String inputValue = "[0x0000000000000000]";
+        long numericInputValue = 0L;
+        long newTimestamp = ThreadLocalRandom.current().nextLong(Long.MAX_VALUE);
+
+        File timeStampedFile = temporaryFolder.newFile();
+        try(FileWriter fileWriter = new FileWriter(timeStampedFile)) {
+            fileWriter.write(inputValue);
+            fileWriter.flush();
+        }
+
+        // when
+        LockedFile lockedFile = new LockedFile(timeStampedFile);
+
+        lockedFile.writeStamp(newTimestamp);
+        long stamp = lockedFile.readStamp();
+
+        // then
+        assertNotEquals(numericInputValue, stamp);
+        assertEquals(newTimestamp, stamp);
+    }
+
+    @Test
+    public void writeStamp_givenNewerTimestampedFile_writeNegativeTimestamp_shouldThrowException() throws IOException {
+        // given
+        String inputValue = "[0x7fffffffffffffff]";
+        long newTimestamp = Long.MIN_VALUE;
+
+        File timeStampedFile = temporaryFolder.newFile();
+        try(FileWriter fileWriter = new FileWriter(timeStampedFile)) {
+            fileWriter.write(inputValue);
+            fileWriter.flush();
+        }
+
+        // when
+        LockedFile lockedFile = new LockedFile(timeStampedFile);
+
+        try {
+            lockedFile.writeStamp(newTimestamp);
+            fail("This should throw an exception");
+        } catch (IOException ioException) {
+            // then
+            assertTrue(ioException.getMessage().contains("trying to overwrite existing value"));
+            assertTrue(ioException.getMessage().contains("with an earlier timestamp"));
+        }
+    }
+
+    @Test
+    public void writeStamp_givenTimestampedFile_writeSameTimestamp_shouldLeaveFileAlone() throws IOException {
+        // given
+        String inputValue = "[0x7fffffffffffffff]";
+        long numericInputValue = Long.MAX_VALUE;
+        long newTimestamp = Long.MAX_VALUE;
+
+        File timeStampedFile = temporaryFolder.newFile();
+        try(FileWriter fileWriter = new FileWriter(timeStampedFile)) {
+            fileWriter.write(inputValue);
+            fileWriter.flush();
+        }
+
+        // when
+        LockedFile lockedFile = new LockedFile(timeStampedFile);
+
+        lockedFile.writeStamp(newTimestamp);
+        long stamp = lockedFile.readStamp();
+
+        // then
+        assertEquals(numericInputValue, stamp);
+        assertEquals(newTimestamp, stamp);
+    }
+}