Fixed test.

get-base-sha.sh

@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+
+set -eu
+
+if [[ -n $INPUT_PATH ]]; then
+  REPO_DIR="$GITHUB_WORKSPACE/$INPUT_PATH"
+
+  echo "Resolving repository path: $REPO_DIR"
+  if [[ ! -d "$REPO_DIR" ]]; then
+    echo "::error::Invalid repository path: $REPO_DIR"
+    exit 1
+  fi
+  cd "$REPO_DIR"
+fi
+
+if [[ -n "$INPUT_SINCE" ]]; then
+  BASE_SHA=$(git log --format="%H" --date=local --since="$INPUT_SINCE" --reverse | head -n 1)
+  if [[ -z "$BASE_SHA" ]]; then
+    echo "::warning::The BASE_SHA for date '$INPUT_SINCE' couldn't be determined."
+  fi
+  echo "::set-output name=base_sha::$BASE_SHA"
+elif [[ -n "$INPUT_BASE_SHA" ]]; then
+  echo "::set-output name=base_sha::$INPUT_BASE_SHA"
+else
+  LAST_REMOTE_COMMIT="$GITHUB_EVENT_BEFORE"
+
+  if [[ -z "$LAST_REMOTE_COMMIT" || "$LAST_REMOTE_COMMIT" == "0000000000000000000000000000000000000000" ]]; then
+    LAST_REMOTE_COMMIT=$(git rev-parse "$(git branch -r --sort=-committerdate | head -1)")
+  fi
+  if [[ "$INPUT_SHA" == "$LAST_REMOTE_COMMIT" ]]; then
+    LAST_REMOTE_COMMIT=$(git rev-parse "$INPUT_SHA^1")
+  fi
+  echo "::set-output name=base_sha::$LAST_REMOTE_COMMIT"
+fi