georgberky#9 start error handling tests

 Co-Authored-By: Sandra Parsick <[email protected]>

src/main/kotlin/com/github/helpermethod/NativeGitProvider.kt

@@ -3,7 +3,7 @@ package com.github.helpermethod
 import org.apache.commons.io.IOUtils
 import java.nio.file.Path
 
-class NativeGitProvider(val localRepositoryDirectory: Path) : GitProvider {
+open class NativeGitProvider(val localRepositoryDirectory: Path) : GitProvider {
     //TODO: find the right path to git command
 
     override fun hasRemoteBranch(remoteBranchName: String): Boolean {
@@ -23,9 +23,14 @@ class NativeGitProvider(val localRepositoryDirectory: Path) : GitProvider {
     }
 
     override fun add(filePattern: String) {
-        val returnValue = runInProcess("git", "add", filePattern)
-
-        //TODO: handle non-zero return values
+        val command = arrayOf("git", "add", filePattern)
+        val returnValue = runInProcess(*command)
+
+        if(returnValue != 0) {
+            throw ProcessException("Native git invocation failed. " +
+                    "Command: ${command.joinToString(" ")}, " +
+                    "return value was: $returnValue")
+        }
     }
 
     override fun commit(author: String, message: String) {
@@ -49,7 +54,7 @@ class NativeGitProvider(val localRepositoryDirectory: Path) : GitProvider {
         return runInProcessWithOutput(*command).first
     }
 
-    fun runInProcessWithOutput(vararg command: String): Pair<Int, String> {
+    open fun runInProcessWithOutput(vararg command: String): Pair<Int, String> {
         val process = ProcessBuilder(*command)
                 .directory(localRepositoryDirectory.toFile())
                 .start()
@@ -59,4 +64,8 @@ class NativeGitProvider(val localRepositoryDirectory: Path) : GitProvider {
 
         return Pair(returnValue, processOutput)
     }
+
+    class ProcessException(message: String?) : RuntimeException(message) {
+
+    }
 }

src/test/kotlin/com/github/helpermethod/NativeGitProviderErrorHandlingTest.kt

@@ -0,0 +1,42 @@
+package com.github.helpermethod
+
+import org.assertj.core.api.Assertions.assertThatCode
+import org.assertj.core.api.Assertions.assertThatThrownBy
+import org.junit.jupiter.api.Assertions.*
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.io.TempDir
+import java.io.File
+
+internal class NativeGitProviderErrorHandlingTest {
+
+    private var processOutput: String = ""
+    private var returnValue: Int = 0
+    private lateinit var gitProvider: NativeGitProvider
+
+    @TempDir
+    lateinit var tempDir: File
+
+    @BeforeEach
+    internal fun setUp() {
+        gitProvider = object : NativeGitProvider(tempDir.toPath()) {
+            override fun runInProcessWithOutput(vararg command: String): Pair<Int, String> {
+                return Pair(returnValue, processOutput)
+            }
+        }
+    }
+
+    @Test
+    internal fun `error handling`() {
+        returnValue = -1
+
+        val callAdd = { gitProvider.add("") }
+
+        assertThatThrownBy(callAdd)
+                .isInstanceOf(NativeGitProvider.ProcessException::class.java)
+                .hasMessageContaining("return value")
+                .hasMessageContaining("-1")
+                .hasMessageContaining("git add")
+    }
+}
+