feat(project): Add GitHub Actions testing workflow (#289)

GitHub actions is a workflow engine.
This testing workflow will
- keep everything inside GitHub (one platform)
- reduce dependency to an external service (TravisCI)
- introduce stricter testing (next to unit tests, staticcheck, fmt, vet)

* fix(tests): TestIssueService_GetEditMeta_Fail fails on windows due to error message checking

We check the error string in TestIssueService_GetEditMeta_Fail.
On different operting systems, this error message is different. See

- Linux: TestIssueService_GetEditMeta_Fail: metaissue_test.go:456: Error Get "http://127.0.0.1:65328/rest/api/2/issue/PROJ-9001/editmeta": dial tcp 127.0.0.1:65328: connect: connection refused
- Windows: Error Get "http://127.0.0.1:50122/rest/api/2/issue/PROJ-9001/editmeta": dial tcp 127.0.0.1:50122: connectex: No connection could be made because the target machine actively refused it.

Now we check the error type instead of the error message

* chore(tests): Support only the current + the last two versions

go-jira follows Go's Release Policy for testing.
See https://golang.org/doc/devel/release.html#policy

Related #290

.github/workflows/testing.yml

@@ -0,0 +1,43 @@
+name: Tests
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  test:
+    name: Test and lint
+    strategy:
+      matrix:
+        go-version: [1.x, 1.13.x, 1.12.x]
+        platform: [ubuntu-latest, windows-latest]
+    runs-on: ${{ matrix.platform }}
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-go@v2
+        with:
+          go-version: 1.14
+
+      # Caching go modules to speed up the run
+      - uses: actions/cache@v1
+        with:
+          path: ~/go/pkg/mod
+          key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+          restore-keys: |
+            ${{ runner.os }}-go-
+
+      - name: Run go fmt
+        if: runner.os != 'Windows'
+        run: diff -u <(echo -n) <(gofmt -d -s .)
+
+      - name: Run go vet
+        run: make vet
+
+      - name: Run staticcheck
+        run: make staticcheck
+
+      - name: Run Unit tests.
+        run: make test

metaissue_test.go

@@ -3,7 +3,7 @@ package jira
 import (
 	"fmt"
 	"net/http"
-	"strings"
+	"net/url"
 	"testing"
 )
 
@@ -451,9 +451,8 @@ func TestIssueService_GetEditMeta_Fail(t *testing.T) {
 		t.Error("Expected to receive an error, received nil instead")
 	}
 
-	expectedError := "connection refused"
-	if !strings.Contains(err.Error(), expectedError) {
-		t.Errorf("Expected to receive error containing %s, received %v instead", expectedError, err.Error())
+	if _, ok := err.(*url.Error); !ok {
+		t.Errorf("Expected to receive an *url.Error, got %T instead", err)
 	}
 }